Journal of Sugar Beet Research - Vol

Journal 

of 

Sugar Beet 

Research 

Volume 45 

Numbers 1 & 2 

January - June, 2008 

ISSN 0899-1502 

Published by 

American Society of Sugar Beet Technologists 

Office of the Executive Vice President 

800 Grant Street, Suite 300 

Denver Colorado 80203 

Made in the United States of America

Contents 

Growth Promotion May Compensate for Losses 

Due to Moderate Aphanomyces Root Rot 

.....................................................................................................1 

Michael S. Metzger and John J. Weiland 

Sugarbeet Response to Nitrogen under Sprinkler 

and Furrow Irrigation 

...................................................................................................19 

J. L.A. Eckhoff and C.R. Flynn 

Influence of Curly Top and Poncho Beta 

on Storability of Sugarbeet 

...................................................................................................31 

Carl A. Strausbaugh, Eugene Rearick, and Stacey Camp 

Economics of Weed Management Systems in Sugarbeet 

...................................................................................................49 

Dennis C. Odero, Abdel O. Mesbah, Stephen D. Miller

January - June 2008 Moderate Aphanomyces Root Rot 1 

Growth Promotion May 

Compensate for Losses Due to 

Moderate Aphanomyces Root Rot 

Michael S. Metzger 1,3 and John J. Weiland 1,2 

1 Department of Plant Pathology, North Dakota State University, 

Fargo ND, 58105 USA and 2 USDA-ARS, Red River Valley 

Agricultural Research Center, Sugarbeet and Potato Research Unit, 

Fargo, ND 58105 USA. 3 Current Address: Minn-Dak Farmers 

Coop, Wahpeton, ND 58075 USA. Corresponding author: 

John Weiland (john.weiland@ ars.usda.gov) 

Mention of a trademark or proprietary product does not constitute a 

guarantee or warranty of the product by the USDA or imply approval to 

the exclusion of other products that may also be suitable. 

ABSTRACT 

A two-year study investigated the use of chemicallyinduced 

resistance and biocontrol bacteria for reducing 

sugarbeet root rot disease caused by the oomycete organism 

Aphanomyces cochlioides. Stand establishment, yield, 

and quality analysis of sugarbeet from replicated field 

plots, as well as root rot of seedlings grown in controlled 

conditions, were analyzed. Bacterial isolates AMMDR1 of 

Burkholderia cepia and PRA25rifz of Pseudomonas fluorescens 

were tested for their ability to inhibit reductions in 

stand and yield caused by A. cochlioides. A commercially 

available inducer of systemic resistance (harpin protein 

formulated as Messenger TM ) also was tested in the field for 

the ability to reduce root rot disease, whereas the inducers 

harpin, salicylic acid, and riboflavin were tested in growthchamber 

studies. Field and growth chamber data combined 

suggested that a subset of the biological treatments in 

combination with chemical treatments enhanced root yield 

and recoverable sugar over control treatments even when 

stand and root rot ratings were unimproved. Integration of 

induced resistance and biocontrol with cultural practices, 

chemical treatments, and heritable resistance may lead to

2 Journal of Sugar Beet Research Vol. 45 Nos. 1 & 2 

improved control of Aphanomyces diseases of sugarbeet. 

Additional key words: Beta vulgaris, Aphanomyces cochlioides, 

biocontrol, Pseudomonas fluorescens, Burkholderia cepacia, harpin, 

induced systemic resistance. 

Seedling damping off and chronic root rot of sugarbeet caused by 

Aphanomyces cochlioides Drecsh. (Dreschler, 1928) has caused 

historic and recent losses to producers in the Red River Valley of 

Minnesota and North Dakota and other production regions of the United 

States. The pathogen is an oomycete, distantly related to Pythium 

and Phytophthora (Drechsler 1929, Dick, 1990). Zoospores are the 

infectious entity produced by the pathogen, whereas oospores are the 

stable resting stage of the organism, capable of surviving many years 

in the infested soil (Papavizas and Ayers, 1974; Park and Grau 1992). 

Seedling root rot disease is favored by warm, wet soils (Duffus and 

Ruppel, 1993); hence stand establishment is improved in soils known to 

contain the pathogen when seed is sown early in the spring when temperatures 

are cooler. Chronic root rot typically occurs in June and July 

in Minnesota and North Dakota following wet periods with seasonable 

temperatures. In 2000 alone, estimates of nearly 20% locally (Fargo, 

ND) and 4% total, of the sugarbeet hectares in the American Crystal 

Sugar Company’s factory districts were abandoned due to the chronic 

root rot caused by this pathogen (A. Cattanach, American Crystal Sugar 

Company, pers. comm.). 

Although resistance active in young and mature beets has been 

characterized (Coe and Scheider, 1966), seedlings must be protected 

from A. cochlioides by seed treatment with the chemical hymexazol 

(TachigarenTM ; Windels, 1990; Payne and Williams, 1990). Since protection 

of the crop by this solitary compound is considered precarious, 

new measures for controlling black root and root rot disease continue to 

be investigated. Biocontrol using beneficial bacteria or fungi offers one 

avenue for disease control that potentially would expedite product registration 

and provide season-long crop protection (Cook and Baker, 1983; 

Handelsman and Stabb, 1996). Biocontrol studies using bacterial species 

antagonistic to A. cochlioides have been described (Jacobsen et al., 

2000; Williams and Asher, 1996; Kristek et al., 2006), but to date none 

are used in major sugarbeet producing regions. This is due in part to the 

lack of bacterial strains proven to provide protection under a wide range 

of environments, to the formulation of such organisms to meet industry 

and regulatory standards and practices, and to education regarding the 

most effective way to implement a biocontrol partner in an integrated


disease-management scheme (Cook and Baker, 1983; Weller, 2007). 

Lack of consistent control measures for chronic root rot disease 

caused by A. cochlioides prompted the initiation of a study aimed at 

the discovery of new, safe components for disease control that would 

simultaneously accelerate the transfer of any discovered technology to 

producers. During the 2001 and 2002 growing seasons, two biological 

control bacteria known to suppress the pathogen Aphanomyces euteiches 

(King and Parke, 1993), the causal agent of pre- and post-emerge 

damping-off in pea and a close relative of A. cochlioides, were field 

tested along with an inducer of systemic resistance for their ability to 

control Aphanomyces root rot on sugarbeet in the Red River Valley 

of Minnesota and North Dakota. The experiments were paralleled by 

growth chamber tests for systemic inducer and biocontrol protection of 

sugarbeet seedlings against black root disease. 

MATeRIALS AnD MeThoDS 

Growth Chamber Studies 

Seed of Maribo 9369 (American Crystal Sugar Coop, Moorhead, 

MN), a hybrid susceptible to A. cochlioides, was treated with metalaxyl, 

thiram and hymexazol according to industry standards (McMullen and 

Bradley 2002), with the application of hymexazol at 45 g per 100,000 

seeds. Seed was sown in Sunshine Mix #1 (Sungro Horticulture, Seba 

Beach, Canada) and sprouted to a stand of 5 seedlings per conetainer 

(Stuewe and Sons, Corvallis OR) in a greenhouse with an average temperature 

of 22°C. The bacterial species P. fluorescens PRA25rifz and B. 

cepacia AMMDR1 (generously provided by Dr. Jennifer Parke, Oregon 

State University) were maintained on nutrient agar or in liquid nutrient 

broth (BD Biosciences, Franklin Lakes, NJ). 

The bacterial isolates B. cepacia AMMDR1 and P. fluorescens 

PRA25rifz were aseptically cultured in nine-centimeter Petri dishes 

containing standard nutrient agar. After incubation at 22°C for 24 h, 

the bacterial isolates were transferred into 500 ml of nutrient broth. The 

cultures were incubated at 26°C rotating at 100 rpm for 48 h after which 

they were analyzed for optical absorbance (Ultrospec 4050 spectrophotometer, 

Cambridge, England). Bacterial cell concentrations of 109 

CFU per ml were used for seed treatments in 2001 and concentrations 

of 10 9 (B. cepacia) and 10 7 (P. fluorescens) CFU per ml were used in 

2002 (Madigan et al. 1997). For the 2001 tests, approximately 300 g of 

untreated medium-sized Maribo 9369 sugarbeet seed was added to the 

B. cepacia AMMDR1 liquid culture and allowed to soak on an orbital 

shaker for 2 h at 100 rpm. Seeds were then transferred with a stainless


steel spatula onto several flat 30.48 by 60.96 centimeter plastic trays and 

placed into a laminar flow hood (Environmental Air Control Inc., Model 

6467, Hagerstown, MD) overnight for air-drying. Fungicide coatings on 

the seeds necessitated treatment of the 2002 bacterial applications differently 

from 2001 applications. In 2002, 600 g of seed to be treated with 

bacteria were distributed in a tray, leveled by hand, and placed inside 

of a fume hood (Model PL-301, Two Rivers, WI) to aid in air-drying. 

Bacterial suspensions in nutrient broth were sequentially applied (~5 

ml per application) to each of the three seed variables (Table 1) at 30 

min time intervals utilizing an air-powered liquid atomizer (Model #15, 

Devilbiss, Somerset, PA) pressurized to 8.28 Pa 4 . Seed was allowed to 

dry in between applications in an effort to retain the chemical fungicide 

coatings. A total of 10 applications were made amounting to 50 ml of 

applied bacterial suspension. Seed was dried overnight before packaging 

and was stored at 4°C for no longer than 20 days before planting. 

Resistance inducing compounds (RIs) were applied to 14 day-old 

seedlings 2 days prior to inoculation with A. cochlioides. Solutions 

of the RIs harpin (Messenger TM , Eden Biosciences, Bothell, WA), 

riboflavin, and salicylic acid (SA) were prepared in distilled water at 

the concentrations of 40 µg/ml (a 10-fold concentrate with respect to 

the field application rate recommended by the manufacturer), 7 µg/ml 

(Aver’yanov et al., 2000), and 2.8 mg/ml (Rasmussen et al., 1991), 

respectively, to a final volume of 50 ml. The RIs were transferred to 

a pressurized tank sprayer (Stanley Model 7402, Chapin Mfg., Batavia 

NY) adjusted to 6.9 Pa 4 and applied at a rate of 0.5 ml/conetainer. 

Zoospores of A. cochlioides isolate 898A(IV) were produced by 

standard methods (Parke and Grau, 1992) and quantitated microscopically 

on a haemocytometer. Zoospore suspensions were applied to the 

conetainers in 5 ml aliquots resulting in seedling exposure to 30, 100, 

300, 1000, and 10,000 spores per treatment. Plants were maintained in 

a growth chamber (Conviron Model PGR15, Winnipeg, Manitoba) at 26 

degrees Centigrade under a 16 hr daylength until harvested for disease 

rating. The root rot index (RRI) described by Beale et al. (1994), calculated 

as 

Σ (Disease rating X number of plants with rating) 

RRI = ------------------------------------------------------------------- X 100 

(Total number of emerged seedlings X 3) 

was used to evaluate seedling damage at 6 days post-inoculation (dpi) 

using a rating scale of 0 = healthy root, 1 = light brown hypocotyl, water 

soaked, 2 = hypocotyl brown, moderate amount of constriction, and 3 =


hypocotyl brown, constricted or root dead. 

Field experiments 

During both the 2001 and 2002 growing seasons, field plots 

were established within commercial fields located near Hillsboro, 

ND and Perley, MN contracted to American Crystal Sugar Company 

(Moorhead, MN) as Aphanomyces Specialty Sites and chosen for the 

testing of varietal response to this pathogen. Soils were indexed for 

Aphanomyces infestation according to Windels and Nabben-Schindler 

(1991). Seedlings were visually rated on a 0 to 3 scale as above. Root 

rot index values (0-100 scale, 0=Healthy, 100=Total Mortality) averaged 

72 for Hillsboro and 68 for Perley in 2001, while the sites for 2002 

averaged 88 and 64, respectively. As in the growth chamber studies, 

variety Maribo 9369 was used for all treatments and for soil indexing. 

Treatments and Plot Design 

At both locations and during both years, the experiment was 

arranged as a randomized complete block design. Each individual 

plot consisted of four rows, each 15.24 meters long and spaced at the 

sugarbeet production standard of 55.88 cm apart (0.0034 hectares per 

individual plot). A 3.05-meter alley for maintenance purposes separated 

all the ranges. 

Three variables were evaluated during the 2001 growing season 

(Table 1). Each treatment was replicated four times at two separate 

locations. All seed used in 2001 lacked fungicide treatment. Treatments 

included an untreated check, weekly foliar treatments of emerged seedlings 

with the commercially-formulated harpin protein, and seed treated 

with B. cepacia AMMDR1 (Table 1). Seed treatment followed methods 

detailed above. 

Eighteen variables were evaluated during the 2002 growing season 

(Table 1). Each variable was replicated three times at each location. 

Base seed treatments in 2002 included untreated seed and seed treated 

with commercial rates of metalaxyl (M; 113.6 g per cwt.) and thiram 

(T; 227.2 g per cwt.). Pelleted seed treated with commercial rates of 

metalaxyl and thiram (hence referred to as MT treated seed) and including 

hymexazol at a rate of 45g per 100,000 seeds. (referred to as MT 

+ H treated seed) made up the third seed treatment. Biological control 

treatments for 2002 included the three seed variables listed above combined 

with the application of B. cepacia AMMDR1 and P. fluorescens 

PRA25rifz to the seed, and post-emergence foliar treatments with a formulation 

of the harpin protein. The three seed variables not receiving 

any type of biological treatments served as the untreated checks.


Table 1. Treatments used in the evaluation of induced resistance and 

biocontrol for the protection of sugarbeet against Aphanomyces root rot. † 

Applied Treatment Seed Growth 2001 2002 

Treatment Chamber Field Field 

B. cepacia - AMMDR1 Raw Seed X X 

Apron/Thiram X 

Tach (45g) X 

Messenger - Micro Rate Raw Seed X 


Tach (45g) X 

Meddenger - 8x Raw Seed X 


Tach (45g) X 

Messenger - 12x Raw Seed X X 


Tach (45g) X 

P. flourescens - PRA25rifz Raw Seed X 


Tach (45g) X 

Untreated Check Apron/Thiram X 

Raw Seed X X X 

Tach (45g) X X 

P. flourescen X 

B. cepacia X 

Riboflavin Raw Seed X 

Tach (45g) X 


B. cepacia X 

Salicylic Acid Raw Seed X 

Tach (45g) X 


B. cepacia X 

Messenger - 1x Raw Seed X 

Tach (45g) X 


B. cepacia X 

† Treatments were applied at both the Perley and Hillsboro locations in both 

years. 

‡ Treatments of B. cepacia and P. fluorescens were applied to the seed: all 

other treatments were applied to seedling or young plant foliage.


Plot Planting, Plot Maintenance, and Stand Counts 

The Hillsboro and Perley Aphanomyces Specialty locations were 

planted on 16 May and 20 May 2001, respectively, while the 2002 

plots were seeded on 18 May and 7 May. Due to a killing frost, the 

2002 Perley location was replanted on 29 May. Plots were managed 

to minimize weed populations (Dexter, et al., 1997), Cercospora leaf 

spot disease (Windels et al., 1998), and insect damage (Khan, 2006) 

using standard industry practices. Herbicide applications were made 

within 12 days of respective plots’ planting date. 

In both 2001 and 2002, stand counts were taken at 15, 30, and 

45 days after planting, as well as a final count during harvest. Multiple 

seedlings are usually counted as a single plant if they emerge less than 

2.54 cm apart (Steen, 2001). Due to lower than average populations 

(less than 150 plants per 30.48 m), however, multiple seedlings were 

counted as two plants regardless of distance. 

harpin Applications 

A solution of harpin (11.45 liters containing 4 µg harpin/ml) was 

transferred to a modified backpack sprayer pressurized to 6.9 Pa 4 (in 

2001) and 13.8 Pa 4 (in 2002) with CO 2 . The solution was applied at 

the labeled rate of 0.011 kg ha -1 using 93.5 L ha -1 of water. The sprayer 

was calibrated to spray 4 rows in unison applying the harpin solution 

at a rate of 2.17 liters every 60 seconds. 

Beginning immediately after seedling emergence, harpin was 

applied either on a weekly basis or according to scheduled herbicide 

treatments. The 2001 Hillsboro site received its first application on 

23 May while applications at Perley were initiated one week later on 

30 May. Research sites for 2002 received their first applications on 29 

May at Hillsboro while application at Perley was on 22 May. Having 

been replanted on 29 May, weekly treatments for the 2002 Perley location 

were reinitiated on 5 June. After their first application, selected 

plots at the 2001 locations received an application every seven days 

for twelve consecutive weeks while selected 2002 plots received 

applications every seven days, continuing in a consecutive pattern 

varying from 4, 8, and 12-week intervals. Plots in 2002 labeled as 

“Messenger – Micro Rate” received foliar harpin applications within 

one hour after the post-emerge herbicides and every week thereafter 

for four consecutive weeks. The latter applications were designed to 

determine the potential for tank mixing the product with herbicide. 

Plot harvest 

The 2001 plots were harvested on 25 September at Hillsboro and


on 28 September at Perley while the 2002 plots were harvested on 24 

September and 17 September, respectively. At three of the four locations, 

only the center two rows were harvested to reduce the effects of 

bordering plots, however, due to lower plant populations at the 2001 

Hillsboro location, all four rows were harvested for yield analysis. 

Each sugarbeet root was visually rated for Aphanomyces root rot and 

recorded on a 0 to 4 scale based on a scale developed by C. Windels, U. 

of Minnesota-Crookston (personal communication): 0 = Clean root; 1 

= Less than 10% of root surface is scurfy; root malformed; 2 = Greater 

than 10% but less than 25% of root surface is scurfy; root malformed; 

3 = Greater than 25% but less than 75% of root surface is scurfy; lower 

half of root rotted or malformed; 4 = Greater than 75% of root surface 

scurfy; and/or no root tip. 

Root samples were transported to the Minn-Dak Farmers 

Cooperative Lab (Wahpeton, ND) for yield and quality analysis within 

12 hours of harvest. Each individual sample (bag of roots) was rated for 

root yield, percent tare, sugar content, and impurity level (sugar loss to 

molasses). Statistical analysis for both locations and for both growing 

seasons was performed using Agricultural Research Manager (ARM 

6.1.12, Gylling Data Management, Inc., Brookings, SD). Assuming a 

randomized complete block design (Treatments: Biologicals, Blocks: 

Seed Chemicals), the data collected was analyzed for least significant 

differences (LSD; Fisher’s Exact Test) at the P = 0.05 level. 

ReSuLTS 

Controlled environment tests with seedlings. 

In agreement with previous reports on the efficacy of harpin protein, 

SA, and riboflavin in the reduction of plant disease symptoms, foliar treatment 

of sugarbeet seedlings with these compounds reduced seedling root 

rot resulting from A. cochlioides challenge. Disease reduction was most 

consistent in treatments involving harpin and SA applications and this 

reduction was observed at several concentrations of A. cochlioides zoospores 

used for inoculation (Fig. 1). Treatment of seed with B. cepacia, 

P. fluorescens and hymexazol in growth chamber studies reduced seedling 

root rot as compared to those of the untreated check after inoculation with 

A. cochlioides zoospores, but in a variable manner. In these experiments, 

hymexazol clearly provided the greatest protection against seedling root rot 

(not shown). The addition of a foliar spray of harpin in conjunction with 

the seed treatments of hymexazol, B. cepacia, and P. fluorescens decreased 

the root rot rating in an additive manner, but the differences exhibited high 

variability and were not statistically significant.

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JSBR Metzger and Weiland 3 


Figure 1 

Figure Fig. 21: 

Seedling root rot from A. cochlioides after prior foliar application 

of harpin and SA in a controlled environment. Check inoculations (-) 

receiving only water on the foliage were compared to seedlings receiving 

harpin (hrp) or salicylic acid (SA). The number of A. cochlioides 

zoospores per treatment (300, 1000, 10,000) is indicated below the 

bars. Asterisks indicate that the foliar treatments resulted in significantly 

reduced average root rot rating (LSD = 9.8) as compared to the 

0.05 

respective control inoculation. 

emergence Rate, Stand establishment and Root Rot Rating. 

At both field locations and in both years, weather conditions were 

favorable for infection of sugarbeet seedlings and adult roots by A. 

cochlioides. Emergence rate was evaluated by recording stand counts 

on each individual plot at 15, 30 and 45-days post planting. Although 

significant differences in stand establishment between treatments were 

observed within a single year, results were not consistent between locations 

or within locations between years. Worth noting, however, was 

the lack of significant decrease in stand establishment with the treatments 

indicating that the biological control agents (BCAs) or harpin 

treatment were not detrimental to seedling growth. 

Due to seasonal summer rainfall and the high incidence of A. 

cochlioides in the chosen test sites, the adult or chronic phase of 

Aphanomyces root rot was prevalent at both locations and in both 

years. Characteristic symptoms such as mild foliar chlorosis and 

severe dwarfing of the roots were observed by early July in the 2001 

and 2002 growing seasons, which increased in severity throughout the 

season. Root symptoms included water-soaked, black discoloration of


the infected area. In plots that were severely affected, many of the roots 

had a proliferation of the lateral roots. During both seasons, the disease 

was more prevalent at the Hillsboro site than it was at the Perley location 

based on pre-plant soil indexing and on the average disease severity of 

harvested roots. 

Yield and Quality Analysis 

Yield components were seen to vary at the Perley and Hillsboro 

experimental locations in both 2001 and 2002. With the high disease 

pressure present at both locations, little significant improvement was 

observed in yield with respect to the test treatments, including treatments 

with hymexazol. An exception in 2001 was the treatment with 

harpin of plants derived from raw seed resulting in increased yields at 

the Hillsboro location as compared to the untreated check (Figure 2). 

Additionally, data from 2002 at the Perley research site showed a significant 

increase in yield and recoverable sugar (Mg ha -1 ) where a combined 

treatment of BCA or harpin treatment with MT+H treatments were 

compared to treatments with MT (Figure 3). Thus, MT+H treatment of 

seed induced yields in 2002 of 2.82 Mg ha -1 which was not significantly 

different than treatment with MT alone; addition of either B. cepacia 

on seed or harpin on the foliage, however, onto MT+H pre-treated seed 

induced yields that were significantly higher than those provided by MT 

treatment alone (LSD 0.05 of 0.94 Mg ha -1 of recoverable sucrose). 

DISCuSSIon 

Aphanomyces root rot of sugarbeet has been a perennial problem in 

production in the Central U.S. and Japan and an increasing problem in 

Europe. The disease impacts both seedlings and adult roots in the field 

(Papvizas and Ayers, 1974) and pre-disposes harvested beets to storage 

rot and sucrose loss through increased respiration (Campbell and Klotz, 

2006). The control of Aphanomyces root rot has relied on a single 

applied chemical, hymexazol, that protects germinating seedlings under 

heavy disease pressure and can maintain an effect through to young 

plants in fields with moderate disease pressure (Windels, 1990; Windels 

and Brantner, 2001). From early growth stages through maturation, 

sugarbeet is dependant upon heritable resistance for protection against 

root rot disease (Coe and Schneider, 1966). 

Results from the present study indicate that the use of the tested 

BCAs as a solitary preventative agent, or induced resistance as a therapeutic, 

have poor efficacy in northern Red River Valley, USA fields in 

reducing chronic root rot caused by A. cochlioides. Although B. cepacia

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and P. fluorescens were documented to reduce root rot caused by A. 

euteiches on pea (King and Parke, 1993), it may be that interactions 

JSBR Metzger and Weiland 4 

between the BCA, and the host, pathogen, and soil components, either 

separately or combined, resulted in the poor disease control observed. 

Interactions between BCAs and host genetics (Smith and Goodman, 

1999) and soil types have been documented (Kristek et al., 2006). A 

lack of any one positive interaction between these BCAs as applied to 

sugarbeet against the A. cochlioides pathogen would explain the lack 

Figure 2 

Figure 3 

Fig. 2: Root yield (top graph) and recoverable sucrose yield (bottom 

graph) in 2001 at Hillsboro, ND after seed treatment with B. cepacia 

and foliar treatment with harpin. All seed, including the untreated check, 

lacked chemical fungicide. The significantly higher root yield (LSD 0.05 = 

13.28 Mg ha -1 ) with the harpin treatment resulted in a higher recoverable 

sucrose per hectare (LSD 0.05 = 1.1 Mg ha -1 ).

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of significant control in these tests (Handelsmann and Stabb, 1996; 

Lugtenberg et al., 2001). The observed trend towards improved yield 

in treatments involving the BCAs in fields with moderate disease pressure, 

however, is compelling and warrants further investigation. BCAs 

previously have been shown to be effective at reducing A. cochlioides 

damage to sugarbeet in field studies outside of the Red River Valley 

(Jacobsen et al., 2000; Williams and Asher, 1996; Kristek et al., 2006) 

The induction of systemic resistance in plants by compounds has 

been known for decades (reviewed by Hammerschmidt and Kuc, 1995) 

and harpin originally was investigated for these properties (Wei et al., 

1992). Recent data are more consistent with harpin’s role as a growth 

promoter (Dong et al., 2004), although a species-specific role in disease 

protection probably exists. In agreement with this, harpin exhibited 

only a moderate ability to protect sugarbeet seedlings in a growth 

chamber from the effects of A. cochlioides JSBR when infection Metzger and Weiland was initiated 5 

with zoospores after harpin treatment at the recommended rate. Poor 

disease control also was observed in the field, although this is likely 

compounded by colonization of seedlings by the pathogen before the 

Figure 3 

Fig. 3: Recoverable sucrose (Mg ha -1 ) in 2002 at Perley, MN after seed 

treatment with B. cepacia and foliar treatment with harpin. Untreated 

seed was compare to that possessing MT or MT+H. Additional check, 

biological seed coating, or foliar inducer treatments are indicated below 

the bars. The open diamond (Ø) indicates the check against which the 

significant increase in RSH (denoted by *; LSD 0.05 = 0.94) is noted. 

* 

* 

*


first application of harpin. Nevertheless, the results illustrate the efficacy 

of harpin in increasing yields even when root rot ratings were not 

improved and constitutes the first report to our knowledge of improving 

yields in Aphanomyces infested soils using a foliar-applied resistance 

inducer. The high pressure of A. cochlioides at the two locations best 

explains the reduced control afforded by the industry-standard MT+H 

treatment in 2002. 

Biocontrol strategies continue to offer promise for reducing costs and 

yield losses to producers with an associated reduction in environmental 

degradation (Cook and Baker, 1983; Becker and Schwinn, 1993; Jacobsen 

et al., 2000; Kristek et al., 2006). Yet in few crop industry paradigms has the 

disease control offered by BCAs proved to be as effective as those afforded 

by exogenous chemicals or host genetics. The results presented here point 

to approaches combining chemical, BCA, and induced resistance concepts 

for the formulation of new strategies to protect sugarbeet from yield losses 

due to A. cochlioides infection. It further is anticipated that these concepts 

could be extended to the control of other sugarbeet diseases. 

ACknoWLeDGeMenTS 

The authors gratefully acknowledge Dr. Jennifer Parke, Oregon 

State University for the bacterial isolates and Eden Biosciences, Inc 

for the gift of the Messenger TM used in this study and the technical 

assistance of Gary Nielsen and Jon Neubauer. We are indebted to the 

American Crystal Sugar Cooperative, Moorhead, MN for field plot 

planting and maintenance and to the tare lab of the Minn-Dak Farmers 

Cooperative, Wahpeton, ND for yield and quality analysis. This work 

was supported in part by the Sugarbeet Research and Education Board 

of Minnesota and North Dakota. 

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Beale, J.W., C.E. Windels, and L. L. Kinkel. 1994. Estimation of populations 

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field. 1993 Sugarbeet Research and Extension Reports, 

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Becker, J.O. and F.J. Schwinn. 1993. Control of soil-borne pathogens 

with living bacteria and fungi : status and outlook. Pestic. Sci. 

37: 355-363. 

Campbell, L.G. and K.L. Klotz. 2006. Postharvest storage losses associated 

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Coe, G.E. and C.L. Schneider. 1966. Selecting sugar beet seedlings 

for resistance to Aphanomyces cochlioides. J. Am. Soc. Sugar 

Beet Technol. 14: 164–167. 

Cook, R.J., and K.F. Baker. 1983. The nature and practice of biological 

control of plant pathogens. American Phytopathological 

Society, St. Paul, MN. 

Dexter, A.G., J.L. Luecke, and M.W. Bredehoeft. 1997. Micro rates 

of postemergence herbicides in sugarbeets. 1996 Sugarbeet 

Research and Extension Reports, North Dakota State 

University. 27:62-66. 

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99.

January - June 2008 Sugarbeet Response to Nitrogen 19 

Sugarbeet Response to nitrogen under 

Sprinkler and Furrow Irrigation 

J. L.A. eckhoff and C.R. Flynn 

Montana State University, Eastern Agricultural Research 

Center, 1501 N. Central Ave., Sidney, MT 59270 

ABSTRACT 

nitrogen (n) management is of utmost importance in production 

of a high-yielding, high-quality sugarbeet (Beta 

vulgaris) crop. While not enough n can limit yield, too 

much n can reduce quality, cause surface and ground 

water contamination and increase input costs. In a previous 

study, sugarbeet under sprinkler irrigation was shown 

to have higher impurities and lower extraction than furrow 

irrigated sugarbeet. The objective of the current 

study was to evaluate sugarbeet response to varying rates 

of nitrogen under sprinkler and furrow irrigation. Plots 

with varying rates of nitrogen were set up under a linear 

overhead sprinkler irrigation system and under furrow 

irrigation. each year, the two irrigation sites were located 

in the same field and were separated by 15 sugarbeet rows 

(9 m). Sugarbeet grown under furrow irrigation achieved 

greatest sucrose yield with available n amounts ranging 

from 141-197 kg/ha. under furrow irrigation, sodium and 

amino-n continued to increase as applied n was increased. 

This resulted in sucrose loss to molasses continuing to 

increase with increased applied n, while percent extraction 

continued to decrease. Sugarbeet grown under sprinkler 

irrigation achieved greatest sucrose yield when available n 

ranged from 112-169 kg/ha. Impurities and sucrose loss to 

molasses were significantly increased in sprinkler irrigated 

sugarbeet when n at any rate was applied when compared 

to sugarbeet with no applied n. 

Additional key words: Beta vulgaris, sugarbeet, sprinkler irrigation, 

flood irrigation, nitrogen management


F urrow irrigation is currently the predominant irrigation system 

for sugarbeet in the lower Yellowstone River Valley. The amount 

of irrigated land in this area is expanding, with overhead sprinkler 

irrigation being installed because of its greater application and labor 

efficiency. Land now under furrow irrigation is also being converted to 

sprinkler irrigation systems. 

Good nitrogen (N) management is critical for production of a highyielding, 

high-quality sugarbeet crop. Not enough N can limit yield, 

while too much N can reduce quality (Halvorson, et al., 1978; Adams, et 

al., 1983). Excess N can also cause surface and ground water contamination 

(U.S. Department of Agriculture, 1991) and increases input costs. 

Carter, et al. (1975) compared sugarbeet production under sprinkler 

and furrow irrigation with two rates of N and two irrigation treatments. 

The study was conducted on silt-loam soil in Idaho. Greatest root and 

sucrose yields were achieved with lower rates of N under sprinkler irrigation, 

while greatest root and sucrose yields were achieved with higher 

rates of N under furrow irrigation. Winter (1988, 1990) compared sugarbeet 

response to various N rates under three irrigation levels on clay 

loam soil and reported that sucrose loss to molasses (SLM) increased 

with reduced irrigation because of increased amino-N and possible 

increased K in the root. 

Geleta, et al. (1994) compared furrow, surge, sprinkler and low 

energy precision application (LEPA) irrigation systems. The furrow 

and surge irrigation systems both resulted in greater nitrate-N losses 

to leaching and run-off than the sprinkler or LEPA systems. These 

results were reported for both fine-textured and coarse-textured soils. 

Sharmasarkar et al. (2001) compared drip and furrow irrigation on 

sugarbeet. They reported that sugarbeet yield and sucrose content were 

greater under drip irrigation than under furrow irrigation. Soil was 

sandy loam. 

An irrigation management study conducted at Sidney, MT, from 

1997-2002 compared sugarbeet grown under furrow irrigation and 

sprinkler irrigation (Eckhoff et al. 2005). Less water was applied under 

sprinkler irrigation than under furrow irrigation. Sprinkler irrigated sugarbeet 

consistently had lower sucrose content and greater SLM. Ground 

water under furrow irrigation had greater nitrate concentration than 

ground water under sprinkler irrigation. Runoff water from furrow irrigation 

had greater nitrate concentration than the irrigation water applied 

to the field. There was no runoff under sprinkler irrigation. The authors 

concluded that N was lost to leaching and runoff under furrow irrigation 

while N was not lost under sprinkler irrigation, resulting in more available 

N at the end of the growing season under sprinkler irrigation.


A sugarbeet crop under sprinkler irrigation on clay soil appears to 

need less nitrogen because less N is lost to leaching and runoff. The 

objective of this study was to evaluate sugarbeet response to varying 

rates of nitrogen under sprinkler and furrow irrigation. 


The study was conducted from 2003-2006 at the Montana State 

University Eastern Agricultural Research Center in Sidney, MT. Soil is 

a fine smectitic frigid Vertic Argiustolls (Savage silty clay). Average 

growing season (April-August) precipitation is 27.3 cm. In the fall 

prior to each spring planting season, the site was irrigated, plowed, 

mulched twice and leveled. Residual soil N was measured to a depth 

of 120 cm in 30-cm increments, so that applied N rates could be determined. 

Soil NO 3 -N levels prior to N application for each year are shown 

in Table 1, along with previous crops, N application dates, planting 

dates, harvest dates, irrigation dates, and growing season precipitation 

for each year. In two years of the study, N was applied in the fall and 

immediately incorporated, while in the other two years, N was applied 

in the spring just prior to planting, and immediately incorporated. In all 

years, N was applied in the form of liquid N, 28-0-0. 

Nitrogen rates were randomized with 6 replications under each 

irrigation system. Nitrogen was applied at rates so that available N, 

including residual soil N, to 120 cm was 112, 141, 169, 197, and 225 kg 

N/ha. A check treatment with no applied N was included. 

Irrigation systems were next to each other in the field, but separated 

by 15 rows of sugarbeet, to avoid influence of one irrigation system on 

the other. Rows were 60 cm wide. Each irrigation treatment was 72 

rows wide, with six replications of each N treatment. Furrow irrigation 

was administered using gated pipe, and sprinkler irrigation was an 

overhead, low-pressure system. Furrow irrigation delivered 7.6 cm of 

water with each application, and sprinkler irrigation delivered 2.5 – 3.0 

cm with each application. The two irrigation systems were previously 

compared and shown to result in different quality of sugarbeet when 

the same N rate was used (Eckhoff et al. 2005). In the current study, 

irrigation systems were not compared, but N rates within each irrigation 

system were compared. 

Sugarbeet was planted to stand at a rate of one seed every 10 cm 

(Eckhoff et al, 1991) using a commercial six-row planter with 60 cm 

between rows. The variety was American Crystal Hybrid 927. When 

seedlings were in the two- to four-leaf growth stage, plots were trimmed 

so that plots were 11 m long and six rows wide. Plots were not thinned.


Insecticides, herbicides and fungicides were applied as needed. 

Plots were also hand-weeded. Plots were irrigated when necessary, 

as determined by monitoring soil water. Soil water was monitored in 

2003 and 2006 using a Paul Brown probe, and in 2004 and 2005 using 

ECH 2 O soil probes that were placed under both irrigation regimes. The 

ECH 2 O probes measured soil water at 30 and 60 cm. The years 2004 

and 2005 were dry early in the season and sprinkler irrigated fields 

were irrigated soon after planting while furrow irrigated fields were 

not (Table 1). Furrow irrigated sugarbeet were not irrigated immediately 

after planting because application of furrow flood irrigation water 

before plant establishment can wash out beds, seed, and seedlings. 

One center row of each plot (11 m) was harvested for yield and 

quality determinations. Plot weight was determined in the field, and 12 

to 15 roots were collected from each plot for quality determinations. 

The quality samples were processed for tare and sucrose content in 

the tare laboratory at the Sidney Sugars factory located in Sidney. Brei 

samples were analyzed for sodium (Na), potassium (K), and amino-N 

by AgTerra Technologies, Inc., in Sheridan, WY. Brei samples were 

frozen until analyses were performed. Percent extraction was calculated 

using a modified Carruthers formula (Carruthers et al., 1962). Data 

were analyzed across years for each irrigation system using ANOVA in 

the MSUSTAT program (Lund, 1991). 

ReSuLTS 

Harvest stands under furrow irrigation were not affected by available 

N (Table 2). Differences in root yield, sucrose, or impurities were 

not caused by differences in stand under furrow irrigation. 

The percent sucrose of furrow irrigated sugarbeet decreased as 

available N increased (Table 2). Sugarbeet with the greatest available 

N had significantly lower sucrose content than sugarbeet with 141 kg/ha 

or less available N. 

When analyzed across four years, sugarbeet under furrow irrigation 

had greatest root yield when available N was in the range of 169-197 

kg/ha. Greatest gross sucrose yield and extractable sucrose yield were 

achieved within the range of 141-197 kg/ha available N (Table 2). 

The impurities Na and amino-N increased gradually as more N 

was applied under furrow irrigation, while K was not affected by N rate 

(Table 2). This resulted in a gradual increase of SLM and a gradual 

decrease in percent extraction as available N increased (Table 2). 

Stands under sprinkler irrigation decreased significantly as N rate 

increased (Table 3). This was particularly pronounced when N was


Table 1. Residual soil N and applied soil N on sugarbeet grown under sprinkler and furrow irrigation, Sidney, Montana, 

2003-2006. 

2003 2004 2005 2006 

previous crop, 1 year prior malt barley durum malt barley malt barley 

previous crop, 2 years prior potatoes potatoes sugarbeets sugarbeets 

51 32 82 52 

residual soil N to 120 cm, 

kg/ha 

N application date Oct 4, 2002 Sep 17, 2003 Apr 26, 2005 May 11, 2006 

planting date Apr 28 Apr 22 Apr 26 May 11 

harvest date Sep 18 Oct 1 Sep 27 Sep 26 

growing season precip, cm 22.40 19.35 25.81 30.00 

Jun 30, Jul 24, Jul 

31, Aug 14, Aug 29 

Jun 9, Jul 21, Aug 2, 

Aug 24, Sep 8 

Jun 22, Jul 7, Aug 4, 

Aug 17, Aug 30 

Irrigation dates - flood Jun 30, Jul 16, Jul 

24, Aug 5, Aug 19 

Jun 30, Jul 5, Jul 13, 

Aug 3, Aug 15, Aug 

30 

May 5, Jun 20, Jul 8, 

Jul 14, Jul 20, Aug 

1, Aug 15, Aug 23, 

Sep 6 

Apr 29, May 4, May 

22, Jun 29, Jul 15, 


5, Aug 12, Aug 23, 

Sep 7 

Irrigation dates - sprinkler Jul 1, Jul 12, Jul 17, 


12, Aug 26


Table 2. Root yield, sucrose yield, extractable sucrose yield, impurities, SLM, and percent extraction of furrow irrigated 

sugarbeet with 6 N-rates, Sidney, Montana, 2003-2006. 

Gross 

harvest 

Root sucrose extractable 

stand Sucrose yield yield sucrose yield na k Amino-n SLM extraction 

kg/ha plants/ha percent Mg/ha kg/ha kg/ha ug/g ug/g ug/g percent percent 

Available 

n 

† 78300 18.93d 68.3a 12859a 12218ab 242a 1647 142a 0.95a 95.0c 

112 79040 18.79bcd 70.6ab 13151ab 12465ab 253ab 1608 165ab 0.97a 94.8c 

141 80225 18.84cd 72.4b 13489bc 12758bc 269abc 1625 176b 1.00ab 94.6bc 

169 78750 18.63abc 72.8bc 13410abc 12634abc 293bc 1631 201c 1.05bc 94.3ab 

197 77930 18.50ab 75.5c 13770c 12938c 288bc 1643 215c 1.07c 94.1a 

225 76025 18.39a 70.8ab 12926a 12172a 306c 1632 210c 1.07c 94.1a 

† 52 kg/ha in 2006, 82 kg/ha in 2005, 32 kg/ha in 2004, 51 kg/ha in 2003different letters behind numbers in the same column 

indicate significant difference at probability ≤ 0.05.


Table 3. Root yield, sucrose yield, extractable sucrose yield, impurities, SLM, and percent extraction of sprinkler irrigated 

sugarbeet with 6 N-rates, Sidney, Montana, 2003-2006. 

Gross 

harvest 

Root sucrose extractable 

stand Sucrose yield yield sucrose yield na k Amino-n SLM extraction 

kg/ha plants/ha percent Mg/ha kg/ha kg/ha ug/g ug/g ug/g percent percent 

Available 

n 

† 89590b 19.13c 67.9a 12915a 12240abc 266a 1617a 169a 0.99a 94.8b 

112 87315b 18.59b 71.5bc 13208ab 12398bc 321ab 1754b 211b 1.13b 93.8a 

141 87810b 18.60b 73.7c 13624b 12791c 314ab 1729b 219b 1.13b 93.9a 

169 86230ab 18.47ab 71.5bc 13151ab 12330abc 330b 1711b 226b 1.14b 93.8a 

197 81265a 18.34ab 70.3abc 12780a 11981ab 345b 1682ab 221b 1.13b 93.8a 

225 80990a 18.20a 69.4ab 12566a 11768a 356b 1699b 231b 1.15b 93.6a 

† 52 kg/ha in 2006, 82 kg/ha in 2005, 32 kg/ha in 2004, 51 kg/ha in 2003 different letters behind numbers in the same column indicate 

significant difference at probability ≤ 0.05.


applied just prior planting (data not shown). 

When analyzed across four years, sugarbeets under sprinkler irrigation 

had greatest root yield when available N was in the range of 112- 

197 kg/ha. Gross sucrose yield and extractable sucrose yield were greatest 

with a range of 112-169 kg/ha available N (Table 3). Reductions 

in stand with the higher rates of N may have caused reductions in root 

and sucrose yield. 

Applied N under sprinkler irrigation resulted in increased Na, K and 

amino-N concentrations (Table 3). The concentration of Na increased 

rapidly as available N increased, while K and amino-N concentrations 

were significantly greater when any N fertilizer was applied than when 

no N was applied. Under sprinkler irrigation, K and amino-N concentrations 

increased significantly with the lowest rate of applied N. This 

resulted in significantly greater SLM and significantly lower percent 

extraction with any rate of applied N when compared to the untreated 

check under sprinkler irrigation (Table 3). 

DISCuSSIon 

Higher rates of N significantly reduced harvest stand under sprinkler 

irrigation but not furrow irrigation. Eckhoff et al. (2005) reported no 

difference in harvest stand between sugarbeet grown under sprinkler and 

furrow irrigation. In that study, applied N rates were the same between 

the two irrigation systems, and over the years, ranged from 150-180 

kg/ha of available N. In the current study under sprinkler irrigation, the 

2 highest rates of N, 197 and 225 kg/ha of available N, reduced harvest 

stands to populations significantly lower than those with 141 kg/ha or 

less available N. There appears to be an interaction between sprinkler 

irrigation and high N rates. Less water is applied at each irrigation with 

sprinkler irrigation, so high rates of N may have damaged young sugarbeet 

plants because it was not leached out of the root zone. Sprinkler 

irrigation wets foliage and causes conditions conducive to disease infection. 

Perhaps very high N rates weaken the plants enough to make them 

more susceptible to disease infection. 

The impurities Na and amino-N increased gradually as more N 

was applied under furrow irrigation, while K was not affected by N 

rate (Table 2). This resulted in a gradual increase of SLM and decrease 

in percent extraction as available N increased (Table 2). Any rate of 

applied N under sprinkler irrigation resulted in increased K, and amino- 

N concentrations, (Table 3). The concentration of Na increased rapidly 

as available N increased, while K and amino-N concentrations were 

significantly greater when any N was applied N than when no N was


applied. This resulted in significantly greater SLM and significantly 

lower percent extraction with any rate of applied N when compared to 

the untreated check under sprinkler irrigation (Table 3). Halvorson, et 

al. (1978) reported that excess available N late in the growing season 

resulted in increased crown tissue, which contained much greater concentrations 

of sodium (Na) and amino-N than root tissue. Carter (1986) 

reported that both Na and potassium (K) uptake were associated with 

N uptake, with major concentrations of these impurities located in the 

sugarbeet tops and crowns. The gradual increase of SLM and decrease 

of percent extraction under furrow irrigation (Table 2) indicate that as 

applied N is increased, available N later in the season may increase 

slightly. The rapid increase of SLM and decrease of percent extraction 

under sprinkler irrigation (Table 3) indicate that N is available late in 

the season with any amount of applied N. 

Sugarbeet grown under furrow irrigation achieved greatest root 

and sucrose yield with rates of available N ranging from 169-197 

kg/ha. Under furrow irrigation, Na and amino-N continued to increase 

as applied N was increased. This resulted in SLM continuing to 

increase with increased applied N, while percent extraction continued 

to decrease. 

Sugarbeet grown under sprinkler irrigation achieved greatest root 

and sucrose yield with rates of available N ranging from 112-197 kg/ha. 

Impurities and SLM were significantly increased when any rate of N 

was applied N compared with no applied N. Sugarbeet under sprinkler 

irrigation would not respond in this way under circumstances in which 

the sprinkler is turned on and allowed to run constantly, as is necessary 

with sandy soil. In that case, leaching and runoff would probably result 

in loss of available N. 

ACknoWLeDGeMenT 

This research was funded in part by Sidney Sugars, Inc, the Montana/ 

Dakota Beet Growers Association, and the Montana Fertilizer Advisory 

Committee. 


Adams, R.M., P.J. Farris, and A.D. Halvorson. 1983. Sugar beet N 

fertilization and economic optima: recoverable sucrose vs. root 

yield. Agron. J. 75:173-176.


Carruthers, A., J.F.T. Oldfield, and H.J. Teague. 1962. Assessment of 

beet quality. Fifteenth Annual Technical Conf. of the British 

Sugar Corp. LTD. Nottingham, England. 

Carter, J.N., C.H. Pair, and D.T. Westerrmann. 1975. Effect of irrigation 

method and late season nitrate-nitrogen concentration on 

sucrose production by sugarbeets. J. Amer. Soc. Sugar Beet 

Technol. 18:332-342. 

Carter, J.N. 1986. Potassium and sodium uptake by sugarbeets as 

affected by nitrogen fertilization rate, location, and year. J. 

Amer. Soc. Sugar Beet Technol. 23:121-141. 

Eckhoff, J.L.A., A.D. Halvorson, M.J. Weiss, and J.W. Bergman. 1991. 

Planting populations for nonthinned sugarbeets. Agron. J. 

83:929-932. 

Eckhoff, J. L.A., J.W. Bergman, and C.R. Flynn. 2005. Sugarbeet (Beta 

vulgaris L.) production under sprinkler and flood irrigation. J. 

Sugar Beet Res. 42:19-30. 

Geleta, S., G.J. Sabbagh, J.F. Stone, R.L. Elliott, H.P. Mapp, D.J. 

Bernardo, and K.B. Watkins. 1994. Importance of soil and 

cropping systems in the development of regional water quality 

policies. J. Environ. Qual. 23:36-42. 

Halvorson, A.D., G.P. Hartman, D.F. Cole, V.A. Haby, and D.E. 

Baldridge. 1978. Effect of N fertilization on sugarbeet crown 

tissue production and processing quality. Agon. J. 70:876- 

880. 

Lund, R.E., 1991. MSUSTAT Statistical Analysis Package, Ver. 5.0, 

Montana Ag. Exp. Sta., Montana State University, Bozeman. 

Sharmasarkar, F.C., S. Sharmasarkar, S.D. Miller, G.F. Vamce, and R. 

Zhang. 2001. Assessment of drip and flood irrigation on water 

and fertilizer use efficiencies for sugarbeets. Agric. Water Man. 

46:241-251.


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(and related questions). A reference summary of published 

sources from an agricultural perspective, Washington, D.C. 

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U.S. Govt. Printing Office, Washington, D.C. 

Winter, S. 1988. Influence of seasonal irrigation amount on sugarbeet 

yield and quality. J. Sugar Beet Res. 25:1-10. 

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irrigation. Agron. J. 82:984-988.

January - June 2008 Curly Top and Poncho Beta 31 

Influence of Curly Top and Poncho 

Beta on Storability of Sugarbeet 

Carl A. Strausbaugh 1 , eugene Rearick 2 , 

and Stacey Camp 3 

1 USDA-ARS NWISRL, 3793 North 3600 East, Kimberly, ID 

83341; 2 Amalgamated Research, Inc., Twin Falls, ID 83301; 

and 3 Amalgamated Sugar Co., 50 S. 500 W., Paul, ID 83347. 

Corresponding author: Carl A. Strausbaugh 

(Carl.Strausbaugh@ars.usda.gov) 

ABSTRACT 

Sucrose losses during postharvest storage of sugarbeet 

(Beta vulgaris L.) maybe exacerbated by field diseases. This 

study investigated the influence of curly top (causal agent 

Beet severe curly top virus and related viruses) on storability 

of sugarbeet roots during the 2005 and 2006 growing seasons. 

Three sugarbeet cultivars varying for resistance to 

curly top were evaluated both with and without the insecticide 

seed treatment Poncho Beta (60 g a.i. clothianidin + 

8 g a.i. beta-cyfluthrin/100,000 seed). At harvest, 8-beet 

samples from each cultivar were collected and placed inside 

an outdoor pile. Samples were removed at 40-day intervals 

beginning on 31 october in 2005 and 1 november in 2006. 

Sucrose concentration, frozen and discolored root area, and 

root weight were evaluated. By mid-September plants from 

Poncho Beta treated seed had curly top ratings that were 37 

and 31% lower (P < 0.01) than plants from the untreated 

seed in 2005 and 2006, respectively. After 124 and 131 days 

in storage, roots from Poncho Beta treated seed had 8.5 and 

5% more sucrose than roots from untreated seed in 2005 

and 2006, respectively. Resistant cultivars and insecticide 

seed treatments not only limit losses to curly top in the field, 

but also in long term storage. 

Additional key words: Curtovirus, geminivirus, Beta vulgaris, clothianidin


Storage of sugarbeet in piles is common in production areas with mild 

climates, which allows the factory campaigns to be longer and more 

productive. However, sucrose loss occurs during this storage period. 

Harvest practices, respiration rates, storage rots, and weather conditions 

during and after harvest influence the storability of sugarbeet (Bugbee, 

1993; Jaggard et al., 1997). The respiration required to maintain a viable 

root, may account for 50-60% of the total sucrose loss (Wyse and Dexter, 

1971). On the outer 60 cm of piles, dehydration is a major cause of sucrose 

loss (Bugbee, 1993). Once weight loss in a beet exceeds 25-30%, the root 

can no longer resist microbial development (Bugbee, 1993). Storage rot 

pathogens such as Phoma betae Frank, Botrytis cinerea Pers. ex Fr., and 

Penicillium claviforme Bainier also cause important sucrose losses in storage 

(Bugbee, 1982). In Moorhead, MN, a survey of beet coming into the 

factory from storage piles determined that 1.2% of the tissue was rotted 

(Bugbee and Cole, 1976). This amount of rot may seem small but led to 

a loss of 500 t of sucrose daily and another 800 t lost indirectly because of 

impurities (Bugbee and Cole, 1976). Air flow and temperature control are 

also important in managing sucrose losses in storage piles (Bugbee, 1993; 

Peterson et al., 1980; Wyse, 1978). Diseases in the field may also influence 

storability (Campbell and Klotz, 2006; Campbell et al., 2008; Kenter 

et al., 2006; Smith and Ruppel, 1971; Strausbaugh et al., 2008). 

Curly top is a widespread problem in sugarbeet in semi-arid areas of 

the United States. Curly top on sugarbeet is caused by Beet severe curly top 

virus or a number of closely related species transmitted by the beet leafhopper, 

Circulifer tenellus (Baker) in a circulative-nonpropagative manner (Soto and 

Gilbertson, 2003; Stenger, 1998; Strausbaugh et al., 2007). Curly top nearly 

eliminated the sugarbeet industry in the western U.S. until cultivars with resistance 

became generally available (Bennet, 1971; Blickenstaff and Traveller, 

1979). Control of this disease is still largely based on host resistance. 

Insecticides including seed treatments such as clothianidin may also reduce 

curly top damage (Strausbaugh et al., 2006). However, even the combination 

of host resistance and insecticidal seed treatment (Strausbaugh et al., 2006; 

Strausbaugh et al., 2007) does not keep plants virus free. Therefore, studies 

were conducted to investigate the influence of curly top, host resistance, and 

insecticide seed treatments on the storability of sugarbeet. 


Treatments. 

The study contained six treatments consisting of three commercial 

sugarbeet cultivars with and without Poncho Beta (clothianidin 60 g 

a.i./100,000 seed + beta-cyfluthrin 8 g a.i./100,000 seed). The study was


conducted with roots from the 2005 growing season and repeated using 

roots from the 2006 growing season. The field in the 2005 growing 

season was exposed to natural leafhopper and virus for infection. In the 

2006 growing season, the natural infestation was not adequate for good 

disease pressure. Therefore, 0.5 viruliferous leafhoppers per plant were 

released on 10 July when the plants were getting their first or second 

set of true leaves. The three sugarbeet cultivars used in the study were; 

HM PM21 which had high resistance to curly top, Beta 8600 which was 

intermediate, and HH Phoenix R which was intermediate to susceptible. 

The cultivar HM PM21 was not available in 2006 and thus we included 

HM PM90 in place of HM PM21, since it had a similar level of resistance 

to curly top in previous work (Strausbaugh et al., 2007). 

The six treatments were arranged in a randomized complete block 

design with four replications as four-row plots 10.4 m long with rows 0.6 

m apart. The fields were managed using standard commercial cultural 

practices (Strausbaugh et al., 2006). At harvest, six 8-beet samples from 

each plot were harvested and placed in nylon mesh onion bags. Two of 

the six samples were submitted to the Amalgamated Tare Lab for sugar 

analysis. The remaining four samples were stored outdoors in a shaded 

area until they were placed inside the Twin Falls commercial ventilated 

pile. The storage samples were piled inside a round metal corrugated 

ventilation pipe (0.9 m diameter) on top of plywood in the same experimental 

design and blocks as they were arranged in the field. 

The sample bags inside the pipe covered a 6 m 2 area starting 6.1 m 

in from the end of the pipe. The end of the pipe was covered with straw 

bales. The pipe was located on top of a 30 cm layer of beet to keep it off 

the ground and was covered with 6.1 m of roots. The pile was ventilated 

using the same type of pipe placed 3.7 m on center. The storage pipe 

with the samples was not ventilated and was placed in between the pipes 

used for ventilation. The samples were retrieved at 40 day intervals 

beginning on 31 October in 2005 and 1 November in 2006. Temperature 

inside the storage tube was recorded on a Hobo temperature sensor 

(Onset Computer Corp., Bourne, MA) at 1 h intervals (Fig. 1). 

2005 Field Samples. The field was located on the USDA-ARS 

Research Farm near Kimberly, ID. Wheat had been grown on the field 

the previous year. Sugarbeet cultivars were planted on 6 May 2005. The 

field was mechanically topped and harvested on 27 October with a small 

plot harvester and the roots were placed inside the pipe in the Twin Falls 

ventilated pile on 28 October. 

2006 Field Samples. The field was located on the USDA-ARS

377 

378 

379 

380 

381 

382 

383 

384 

385 

386 

387 

388 

389 

390 

391 

392 


Research Farm near Kimberly, ID. The field had been in field corn in 

2005 and was planted on 11 May. The field got hailed out on 8 June 

and was replanted on 12 June. The sugarbeet plants were hand topped 

and harvested on 17 October. The storage samples were stored outdoors 

in a shaded area until they were placed inside the Twin Falls ventilated 

pile on 19 October. 

Curly Top, Rot, and Freeze Damage Ratings. The plants were evaluated 

for curly top symptoms using a disease index of 0 (= no disease) 

to 9 (= dead plant) (Strausbaugh et al., 2006) on 7 and 12 September in 

10 

8 

6 

4 

2 

0 

-2 

-4 

-6 

-8 

-10 

10 

8 

6 

4 

2 

0 

-2 

-4 

-6 

-8 

-10 

1 11 21 31 41 51 61 71 81 91 101 111 121 131 

1 11 21 31 41 51 61 71 81 91 101 111 121 131 

JS 

Strausbaugh e 

Page 

Days In storage 

Figure Figure 1. Average 1. Average daily daily temperature temperature (°C) (°C) next next to sugarbeet to sugarbeet storage storage samples inside the 

samples inside the storage tube from 27 October 2005 to 28 February 

storage 2006 tube (A) from and from 27 October 19 October 2005 2006 to 28 to February 26 February 2006 2007 (A) (B) and in from an 19 October 200 

outdoor pile in Twin Falls, ID. Arrows designate when storage samples 

26 February were retrieved. 2007 (B) in an outdoor pile in Twin Falls, ID. Arrows designate when 

storage samples were retrieved. 

A 

B


2005 and 2006, respectively. At the time of retrieval from the storage 

pile, root rot was assessed by estimating the percentage of root surface 

area with dry black rot, wet bacterial rot, and/or covered with fungal 

growth. The roots were also visually evaluated to establish the percentage 

of root surface area with freeze damage (frost on root surface, 

tissue translucent, etc.). No freeze data were taken on the first samples 

because no freezing had occurred by this date. There was no evidence 

of insect damage on the roots either at harvest or after storage. Prior to 

storage, there was no evidence of root rot . 

Weight Analysis. Prior to placing the storage samples in the pile, each 

sample was weighed. The samples were reweighed when retrieved from 

the storage pile. A comparison of these weights was used to estimate 

reduction in root weight. 

Sugar Analysis. Two of the six samples collected from each plot 

were submitted to the Amalgamated Tare Lab in Paul, ID at the time 

of harvest. Percent sucrose was determined using an Autopol 880 

polarimeter (Rudolph Research Analytical, Hackettstown, NJ) and a 

half-normal weight sample dilution and aluminum sulfate clarification 

by the method generally described in ICUMSA Method GS6-3 [1994] 

(Bartens, 2005). Percent sucrose for samples coming out of storage 

was determined by Amalgamated Research Inc. in Twin Falls, ID using 

gas chromatography. The gas chromatographic method was similar to 

ICUMSA Method GS4/7/8/5-2 [2002] with the following modifications: 

the internal standard used is D(-)- salicin [2-(hydroxymethyl)phenyl-ß- 

D-glucopyranoside] and equal volumes (to ± 0.01 ml) of a solution of 

internal standard in dimethylformamide were dispensed into weighed 

samples and standards using a volumetric dispenser (Bartens, 2005). 

Previous work comparing the two sampling techniques determined 

that the gas chromatography analysis averaged 1.395% higher than the 

polarimeter (Strausbaugh et al., 2008). To establish percent reduction 

in sucrose at harvest versus storage, only samples from within the same 

plot were compared. Percent sucrose reduction was established using 

the following equation: % reduction in pounds of sugar = (1-[((% Sugar 

storage sample – 1.395) x Weight storage sample )/(% Sugar harvest sample x Weight harvest 

)]) x 100. 

sample 

Data Analysis. Data were analyzed using the general linear models 

procedure of SAS (SAS Institute Inc., 1999), and Fisher’s protected least 

significant difference was used for mean comparisons. Mean comparisons 

across treatments were conducted using single degree-of-freedom


contrast statements. Bartlett’s Test was used to evaluate homogeneity 

of variance. 

ReSuLTS 

Temperature. During the 2005/2006 storage season temperatures 

dropped below 0°C on 3 December 2005 and stayed below zero for the 

next 29 days (Fig. 1). The lowest temperature during the cold period 

was -7.9°C. Temperatures then remained above 0°C for all but two 

days until the end of the storage season. During the 2006/2007 storage 

season temperatures dropped below 0°C for 2 days at the end of October 

and then not again until 25 December 2006. Temperatures fluctuated 

above and below freezing until mid February when they remained above 

freezing until the end of the storage season. The coldest temperature 

recorded was -5.7°C on 17 January 2007. 

Curly top ratings. During the 2005 growing season moderate curly 

top disease pressure was present based only on natural leafhopper 

movement. By 7 September the mean curly top ratings for HM PM21, 

Beta 8600, and HH Phoenix R without Poncho Beta were 2.7, 3.7, and 

5.3, respectively [LSD (P < 0.05) = 0.5]. With Poncho Beta, the same 

three cultivars had ratings of 1.5, 2.1, and 3.8, respectively (Strausbaugh 

et al. 2006). When analyzed across cultivars, the Poncho Beta treatment 

readings averaged 1.97 lower (P < 0.01) than treatment without 

the insecticide. During the 2006 growing season there was moderate 

disease pressure based on inoculation with viruliferous leafhoppers. By 

12 September the mean curly top ratings for HM PM90, Beta 8600, and 

HH Phoenix R without Poncho Beta were 3.7, 4.0, and 4.5, respectively 

[LSD (P < 0.05) = 0.4]. With Poncho Beta, the same three cultivars had 

ratings of 2.5, 2.7, and 3.2 respectively. When analyzed across cultivars, 

the Poncho Beta treatment readings averaged 1.3 lower (P < 0.01) than 

treatments without the insecticide. 

Surface rot. There was no apparent surface rot in the November sampling 

during either year. December data for surface rot from 2005 and 

2006 were analyzed together since they were not significantly different 

(P = 0.15) and variances were homogeneous (P = 0.08). January data 

for surface rot did not differ between years (P = 0.12), but variances 

were not homogeneous (P = 0.03). Thus, these data were analyzed 

individually. February data for surface rot differed between years (P < 

0.01). Roots from the 2005 growing season did not differ in surface rot 

throughout the storage season (Table 1). In roots from the 2006 growing 

season, treatments differed for surface rot in January. HH Phoenix


Table 1. Percentage of root surface exhibiting rot on sugarbeet roots harvested in 2005 and 2006 from curly top infested plots 

with untreated and Poncho Beta treated seed stored in an outdoor commercial pile at Twin Falls, ID. 

Surface rot † 

9 Dec 

2005/2006 18 Jan 2006 28 Feb 2006 22 Jan 2007 26 Feb 2007 

Cultivar Treatment 

HM PM21 Poncho Beta 4.1 15 14 0.9 b 1.0 b 

HM PM21 Untreated 4.2 16 18 0.8 b 0.9 b 

Beta 8600 Poncho Beta 2.6 4 8 2.6 b 2.0 b 

Beta 8600 Untreated 4.5 4 18 2.9 b 8.6 ab 

HH Phoenix R Poncho Beta 4.9 15 20 5.0 b 10.8 ab 

HH Phoenix R Untreated 2.6 16 29 13.8 a 14.6 a 

P > F § 0.8802 0.1312 0.2302 0.0125 0.0595 

LSD (P < 0.05) NS NS NS 7.1 10.6 

† Surface rot = percentage of root area covered by fungal growth or dark tissue discoloration. Sugarbeet were harvested and put into 

storage on 31 October 2005 and 19 October 2006. December data from 2005 and 2006 were analyzed together since they were not 

significantly different (P = 0.1500) and variances were homogeneous (P = 0.0832). 

HM PM90 was used in 2006 instead of HM PM21, since HM PM21 was no longer available. 

§ P > F was the probability associated with the F value. LSD = Fisher’s protected least significant difference value. NS = not significantly 

different. Means followed by the same letter did not differ significantly based on Fisher’s protected least significant difference, 

with P < 0.05.


R without Poncho Beta had more surface rot than the other treatments. 

The February sampling was borderline for significance (P = 0.0595). 

When data were analyzed across cultivars using contrasts, there were 

no significant differences in surface rot with or without Poncho Beta 

(Table 2). 

Frozen root area. There was no frozen root damage evident in either of 

the November samplings. December data for frozen tissue for both years 

were not different (P = 0.20), but variances were not homogeneous (P < 

0.01). Transformation did not create homogeneous variances and thus 

these data were analyzed individually. January and February data for 

frozen tissue differed between years (P < 0.01 and


Table 2. Single degree of freedom contrasts to investigate the influence 

of curly top on sugarbeet roots harvested from plots with untreated and 

Poncho Beta treated seed and stored in an outdoor pile in Twin Falls, ID. 

Variable † Date 

Contrast (mean) 

untreated 

Poncho 

Beta F P > F 

Surface rot (%) Dec 2005/2006 3.8 3.9 0 0.9519 

18 Jan 2006 12.0 11.3 0 0.8162 

28 Feb 2006 21.7 14.0 3 0.1230 

22 Jan 2007 5.8 2.8 2 0.1439 

26 Feb 2007 8.0 4.6 1 0.2486 

Frozen root area (%) 9 Dec 2005 5.7 12.5 1 0.2909 

18 Jan 2006 1.3 0.6 0 0.6330 

28 Feb 2006 0.0 0.0 

12 Dec 2006 0.0 1.7 1 0.3332 

22 Jan 2007 98.3 97.3 3 0.1130 

26 Feb 2007 3.9 0.0 34


Table 3. Percentage of frozen root tissue in sugarbeet roots harvested in 2005 and 2006 from curly top infested plots with 

untreated and Poncho Beta treated seed were stored in an outdoor pile in Twin Falls, ID. 

Frozen root area (%) † 

26 Feb 2007 

normal Transformed § 

Cultivar Treatment 9 Dec 2005 18 Jan 2006 28 Feb 2006 12 Dec 2006 22 Jan 2007 

HM PM21 ‡ Poncho Beta 0.0 1.2 0.0 0.0 95.0 0.0 0.7 b 

HM PM21 Untreated 5.0 0.0 0.0 0.0 100.0 0.0 0.7 b 

Beta 8600 Poncho Beta 12.5 0.5 0.0 5.0 97.5 0.0 0.7 b 

Beta 8600 Untreated 11.2 0.0 0.0 0.0 95.0 11.0 3.3 a 

HH Phoenix R Poncho Beta 25.0 0.0 0.0 0.0 99.5 0.0 0.7 b 

HH Phoenix R Untreated 0.8 3.8 0.0 0.0 100.0 0.8 1.0 b 

P > F 0.2482 0.5843 0.4509 0.2613 F was the probability associated with the F value. LSD = Fisher’s protected least significant difference value. NS = not significantly 

different. Means followed by the same letter did not differ significantly based on Fisher’s protected least significant difference, 

with P < 0.05.


Table 4. Percent reduction in root weight in sugarbeet roots harvested in 2005 and 2006 from curly top infested plots with 

untreated and Poncho Beta treated seed were stored in an outdoor pile in Twin Falls, ID. 

Root weight reduction † 

26 Feb 

2007 

22 Jan 

2007 

12 Dec 

2006 

1 nov 

2006 

28 Feb 

2006 

18 Jan 

2006 

Cultivar Treatment 9 Dec 2005 

HM PM21 Poncho Beta 5.3 6.4 5.7 8.4 10.2 14.3 17.8 

HM PM21 Untreated 4.1 6.8 8.1 12.4 12.2 14.5 14.7 

Beta 8600 Poncho Beta 4.9 7.3 7.1 6.0 8.2 12.6 12.7 

Beta 8600 Untreated 5.2 7.3 6.4 11.0 10.5 15.1 16.6 

HH Phoenix R Poncho Beta 5.0 8.0 6.5 7.5 8.8 14.4 14.0 

HH Phoenix R Untreated 4.1 5.3 8.3 5.4 10.0 15.7 18.3 

P > F § 0.8088 0.6936 0.8347 0.0843 0.3189 0.7985 0.3240 

LSD (P < 0.05) NS NS NS NS NS NS NS 

† Percent reduction in root weight in relation to that determined at harvest. Sugarbeet were harvested and put into storage on 31 October 

2005 and 19 October 2006. 


§ P > F was the probability associated with the F value. LSD = Fisher’s protected least significant difference value. NS = not significantly 

different.


ments. In 2005 roots, HM PM21 lost more sucrose when untreated. In 

2006, Beta 8600 lost more sucrose when not treated, but the difference 

was not present in the 2005 roots. HH Phoenix R with Poncho Beta 

lost more sucrose than the other cultivars with Poncho Beta both years. 

When compared across cultivars, roots with Poncho Beta retained 8.5 

(P = 0.05) and 5% (P = 0.02) more sucrose in 2005 and 2006, respectively 

(Table 2). Regression analysis revealed a significant relationship 

between curly top ratings and sucrose reduction in both 2005 (r 2 = 0.28, 

P < 0.01) and 2006 (r 2 = 0.22, P = 0.02). 

DISCuSSIon 

Curly top of sugarbeet can lead to sucrose reduction in beet stored 

more than 100 days in outdoor piles. The Poncho Beta seed treatment 

reduced curly top symptoms in the field and subsequently was associated 

with reduced sucrose loss of 5 to 8% in long-term storage. The 

reduction in curly top symptoms associated with Poncho Beta had 

almost no measurable influence on surface rot, freeze damage, and 

weight loss in storage. Cultivar selection had a greater impact on storability 

and these data emphasize the importance of resistant cultivars in 

reducing storage losses. 

Recently, the influence of disease problems in the field have been 

studied using Rhizoctonia root rot (Kenter et al., 2006), Cercospora leaf 

spot (Kenter et al., 2006; Smith and Ruppel, 1971), Aphanomyces root 

rot (Campbell and Klotz, 2006), and rhizomania (Campbell et al., 2008; 

Strausbaugh et al., 2008). Based on these recent publications, it could 

be argued that some disease problems can rival if not exceed sucrose 

loss associated with inherent differences in respiration. The reduced 

sucrose loss in storage and reduction in symptoms associated with the 

Poncho Beta treatment suggest that curly top negatively influenced the 

storability of sugarbeet. 

Curly top on sugarbeet can be caused by BSCTV or two other closely 

related species Beet mild curly top virus [BMCTV] and Beet curly top 

virus [BCTV] (Stenger, 1998; Strausbaugh et. al., 2006). Surveys from 

plants in adjacent studies indicate that BSCTV and BMCTV were likely 

to have been present both years (Strausbaugh et al., unpublished data). 

BCTV was also likely to be present in 2006. A previous survey also 

established that BSCTV (formerly known as the CFH strain) was present 

in Idaho (Stenger and McMahon, 1997). Thus, the virus strains and 

disease pressure reported here should be typical of commercial fields 

under moderate curly top infestation. 

The clothianidin in Poncho is a second generation neonicotinoid


Table 5. Percent reduction in sucrose in sugarbeet roots harvested from curly top infested plots with untreated and Poncho 

Beta treated seed were stored in an outdoor pile in Twin Falls, ID. 

Sucrose reduction (%) † 

18 Jan 2006 28 Feb 2006 1 nov 2006 22 Jan 2007 26 Feb 2007 

9 Dec 

2005/2006 

Cultivar Treatment 

HM PM21 Poncho Beta 6.0 5.4 0.9 c 4.0 9.8 14.2 b 

HM PM21 Untreated 6.9 2.4 15.8 ab 9.1 12.4 20.7 ab 

Beta 8600 Poncho Beta 6.1 6.8 4.7 bc 0.8 11.2 14.8 b 

Beta 8600 Untreated 11.3 6.9 14.0 abc 5.4 9.5 24.0 a 

HH Phoenix R Poncho Beta 12.5 16.8 21.8 a 8.0 14.9 24.5 a 

HH Phoenix R Untreated 6.9 10.6 23.1 a 5.8 15.7 23.8 a 

P > F § 0.1728 0.0801 0.0314 0.4009 0.3837 0.0219 

LSD (P < 0.05) NS NS 14.6 NS NS 7.4 

† Percent reduction in sucrose in relation to that determined at harvest. Sugarbeet were harvested and put into storage on 31 October 2005 

and 19 October 2006. December data from 2005 and 2006 for sucrose reduction were analyzed together since they were not significantly 

different (P = 0.2041) and variances were homogeneous (P = 0.3010). There is no data for the first sampling date in 2005 since 

harvest and sampling were almost simultaneous. 


§ P > F was the probability associated with the F value. LSD = Fisher’s protected least significant difference value. NS = not significantly different. 

Means followed by the same letter did not differ significantly based on Fisher’s protected least significant difference, with P < 0.05.


which is a systemic insecticide seed treatment that provides control of 

beet leafhoppers (vector for BSCTV) and subsequent reduction in curly 

top (Strausbaugh et al., 2006). The beta-cyfluthrin component is a nonsystemic 

insecticide that should have had no influence on beet leafhoppers 

or curly top. Although Poncho Beta reduces curly top symptoms, 

the plants still become infected and some symptom development occurs 

even with the most resistant commercial cultivars. Thus, the storage 

data presented represent a comparison between more symptomatic and 

less symptomatic plants. 

The influence of disease problems in the field on the ability of sugarbeet 

tissue to resist freezing is poorly studied. A previous study with 

roots from a rhizomania infested field showed that Beet necrotic yellow 

vein virus could lead to considerable freeze damage (Strausbaugh et al., 

2008). Curly top seemed to have relatively little influence on the risk of 

roots freezing as there were no consistent differences in the data shown 

in Table 3. In December 2005 and January 2006 there was freeze damage 

but subsequent sampling data revealed very little damage. The risk 

of roots freezing in relation to curly top infection in the field may not 

need to be investigated further. 

Curly top in sugarbeet is a widespread important disease problem in 

semi-arid areas of the western United States from Nebraska to California. 

Curly top almost eliminated sugarbeet production until resistance was 

incorporated into commercial cultivars (Bennet, 1971). The primary 

control measure for curly top is host resistance. However, even the most 

resistant commercial cultivars allow for considerable disease development 

(Strausbaugh et al., 2007). Seed treatments such as Poncho Beta 

reduce curly top damage, but should be viewed as a supplement to 

host resistance and not a substitute for host resistance (Strausbaugh et 

al., 2006). Even combining our best host resistance with insecticide 

seed treatments does not eliminate virus from the plants, leaving room 

for further improvement to both host resistance and control measures. 

The storage data indicate Poncho Beta also has the potential to reduce 

storage losses in roots stored for more than 100 days in storage. Sugar 

companies that store sugarbeet roots need to take into consideration the 

influence that cultivar selection can have on sucrose losses. Companies 

operating in areas with curly top and long-term storage need to encourage 

the use of systemic insecticides as seed treatments to reduce or 

minimize sucrose loss in storage.


ACknoWLeDGMenTS 

These data support the objectives for the United States Department 

of Agriculture CRIS project 5368-21220-002-00D. We acknowledge 

the Amalgamated Sugar Co., Amalgamated Research Inc., Beet Sugar 

Development Foundation, and Snake River Sugarbeet Growers for supporting 

our research work. We also wish to acknowledge the efforts of 

the following technical support staff: Diane Patterson, Paul Foote, Jodi 

Smith, Mindie Funke, Dustin Kenney, and Terry Brown. 


Bartens, A. 2005. International Commission for Uniform Methods of 

Sugar Analysis Methods Book 2005. Dr. Albert Bartens KG, 

Berlin. 431 pp. 

Bennett, C. W. 1971. The curly top disease of sugarbeet and other pests. 

Monogr. No. 7. Am. Phytopathological Soc., St. Paul, MN. 

Blickenstaff, C. C., and D. Traveller. 1979. Factors affecting curly top 

damage to sugarbeets and beans in southern Idaho, 1919-77. 

Science and Education Administration, Agricultural Reviews 

and Manuals, Western Series, No. 8. U.S. Dep. Agric.-Agric. 

Res. Serv., Oakland, CA. 

Bugbee, W. M. 1982. Storage rot of sugar beet. Plant Dis. 66:871-873. 

Bugbee, W. M. 1993. Storage. p. 551-570. In D. A. Cooke and R. 

K. Scott (eds.). The Sugar Beet Crop: Science into practice. 

Chapman and Hall, London. 

Bugbee, W. M., and D. F. Cole. 1976. Sugarbeet storage rot in the Red River 

Valley 1974-75. J. Am. Soc. Sugar Beet Technol. 19:19-24. 

Campbell, L. G., and K. L. Klotz. 2006. Postharvest storage losses associated 

with Aphanomyces root rot in sugarbeet. J. Sugar Beet 

Res. 43:113-127. 

Campbell, L. G., K. L. Klotz, and L. J. Smith. 2008. Postharvest storage 

losses associated with rhizomania in sugar beet. Plant Dis. 

92:575-580.


Jaggard, K. W., C. J. A. Clark, M. J. May, S. McCullagh, and A. P. 

Draycott. 1997. Changes in the weight and quality of sugarbeet 

(Beta vulgaris) roots in storage clamps on farms. J. Agric. Sci. 

129:287-301. 

Kenter, C., C. Hoffmann, and B. Märländer. 2006. Sugarbeet as raw 

material – Advanced storage management to gain good processing 

quality. Sugar Industry 131:1-15. 

Peterson, C. L., D. J. Traveller, and M. C. Hall. 1980. Loss of sucrose 

during controlled and conventional storage. J. Am. Soc. Sugar 

Beet Technol. 20:517-530. 

SAS Institute, Inc. 1999. The SAS system for Windows. Version 8.2. 

SAS Institute Inc., Cary, NC. 

Smith, G. A. and E. G. Ruppel. 1971. Cercospora leaf spot as a predisposing 

factor in storage rot of sugar beet roots. Phytopathology 

61:1485-1487. 

Soto, M. J., and R. L. Gilbertson. 2003. Distribution and rate of movement 

of the curtovirus Beet mild curly top virus (family Geminiviridae) 

in the beet leafhopper. Phytopathology 93:478-484. 

Stenger, D. C. 1998. Replication specificity elements of the Worland 

strain of beet curly top virus are compatible with those 

of the CFH strain but not those of the Cal/Logan strain. 

Phytopathology 88:1174-1178. 

Stenger, D. C., and C. L. McMahon. 1997. Genotypic diversity of 

beet curly top virus populations in the western United States. 

Phytopathology 87:737-744. 

Strausbaugh, C. A., A.M. Gillen, J.J. Gallian, S. Camp, and J.R. Stander. 

2006. Influence of host resistance and insecticide seed treatments 

on curly top in sugar beets. Plant Dis. 90:1539-1544. 

Strausbaugh, C. A., A. M. Gillen, S. Camp, C. C. Shock, E. P. Eldredge, 

and J. J. Gallian. 2007. Relationship of beet curly top foliar ratings 

to sugar beet yield. Plant Dis. 91:1459-1463.


Strausbaugh, C. A., E. Rearick, S. Camp, J. J. Gallian, and A. T. Dyer. 

2008. Influence of Beet necrotic yellow vein virus on sugar beet 

storability. Plant Dis. 92:581-587. 

Wyse, R. E. 1978. Effect of low and fluctuating temperatures on the 

storage life of sugarbeets. J. Am. Soc. Sugar Beet Technol. 

20:33-42. 

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in several sugarbeet varieties during storage. J. Am. Soc. Sugar 

Beet Technol. 16:390-398. 

Mention of trade names or commercial products in this article is solely 

for the purpose of providing specific information and does not imply recommendation 

or endorsement by the U.S. Department of Agriculture.

January - June 2008 Economics of Weed Management 49 

economics of Weed Management 

Systems in Sugarbeet 

Dennis C. odero 1 , Abdel o. Mesbah 2 , 

Stephen D. Miller 3 

1 University of Wyoming, Department of Plant Sciences, P. O. Box 

3354, Laramie, WY 82071; 2 University of Wyoming, Powell Research 

and Extension Center, 747 Road 9, Powell, WY 82435; 3 University of 

Wyoming, Agricultural Experiment Station, P. O. Box 3354, Laramie, 

WY 82071. Corresponding author: D. C. Odero (odero@uwyo.edu) 

ABSTRACT 

Irrigated field studies were conducted in 2004 and 2005 

at the university of Wyoming Research and extension 

Centers to evaluate herbicide programs and hand hoeing 

for weed management in sugarbeet. Preplant ethofumesate 

applications followed by standard-split or micro-rate 

herbicide programs controlled common lambsquarters 

(Chenopodium album L.) and green foxtail [Setaria viridis 

(L.) Beauv.]. Common lambsquarters control was 6% 

greater when four micro-rate applications were made 

compared with three micro-rate applications. Increasing 

the number of applications of either the standard-split or 

micro-rate herbicide programs improved green foxtail control 

6 to 7% compared with lower number of applications 

of both programs. Common lambsquarters control was 

16% greater with the standard-split rate program compared 

with the micro-rate program. Sugarbeet root yields 

were 6.97 Mg/ha greater when ethofumesate was applied 

preplant prior to the postemergence herbicide applications 

compared with postemergence herbicide programs alone. 

Standard-split herbicide programs resulted in 3.48 Mg/ha 

more root yield compared with the micro-rate herbicide 

program. even with the additional cost of preplant ethofumesate, 

this treatment resulted in $214.92/ha higher net 

economic return compared with treatments where ethofumesate 

was not applied. The addition of hand hoeing to 

all herbicide treatments resulted in higher root yields and


net economic returns. Treatments that provided good weed 

control and resulted in high root and extractable sucrose 

yields performed well economically. 

Additional key words: Full-rate, lay-by, grass herbicide 

Sugarbeet is a high value crop requiring high annual expenditure for 

production. Weed management is one of the main production costs 

associated with sugarbeet. A large portion of this cost of production 

is spent establishing stands of weed-free sugarbeet. Sugarbeet is very 

sensitive to early weed competition because of slow canopy closure 

and low plant height (Scott and Wilcockson 1976). Producers often use 

a combination of herbicides and mechanical measures including hand 

labor to obtain adequate stands of weed-free sugarbeet. 

Sugarbeet weed control programs generally consist of multiple 

herbicide applications, preemergence (PRE) followed by multiple postemergence 

(POST) herbicide applications or just multiple POST 

herbicide applications in order to provide season-long control of many 

annual weeds (Miller and Fornstrom 1988, 1989; Wicks and Wilson 

1983). Phenylcarbamate herbicides are the foundation of these programs 

and are used either alone or in combination with other herbicides. 

The most commonly used phenylcarbamate herbicides in sugarbeet 

are desmedipham or a mixture of desmedipham and phenmedipham. 

Phenylcarbamate herbicides can cause sugarbeet injury, especially 

when applied as a single full-rate application (Dexter 1994). The need 

to reduce sugarbeet injury from phenylcarbamate herbicides resulted 

in the development of weed control programs that split the full-rate 

(standard-split rate) of the phenylcarbamates herbicides into two or 

three applications. Split applications reduced sugarbeet injury and 

improved weed control when compared with a single full-rate application 

(Dexter 1994). Split applications of phenylcarbamate herbicides 

are presently applied at the cotyledon to two-leaf stage of sugarbeet 

with sequential treatments applied as needed at 7 to 10 day intervals. 

The phenylcarbamate herbicides are commonly tank mixed with triflusulfuron 

and clopyralid for broad-spectrum weed control (Miller et al. 

1994; Morishita and Downard 1995). Recently, growers have adopted 

the micro-rate program for weed control in sugarbeet. The micro-rate 

program involves sequential application of combinations of phenylcarbamate 

herbicides, triflusulfuron, and clopyralid applied at lower rates 

than the standard-split programs and this mixture is applied with methylated 

seed oil. This program was developed to reduce sugarbeet injury 

from standard-split herbicide applications and to reduce the herbicide


input costs while maintaining weed control. 

Effective season-long weed control can be accomplished when 

POST phenylcarbamate herbicides are used in combination with PRE 

herbicide such as ethofumesate (Miller and Fornstrom 1988, 1989). 

Incorporation into the soil by mechanical means, irrigation, or precipitation 

has generally improved the efficacy of PRE herbicides (Dexter 

1997). Ethofumesate can also be applied POST and the efficacy of 

ethofumesate has often been increased when used in combination with 

phenmedipham, desmedipham, clopyralid, and triflusulfuron (Miller 

and Fornstrom 1988, 1989). Triflusulfuron is a low use rate POST herbicide 

that provides safe and effective control of larger weeds in sugarbeet 

when tank-mixed with phenylcarbamates (Morishita and Downard 

1995). Clopyralid can also be tank-mixed with phenylcarbamate herbicides 

to broaden the spectrum of weed control in sugarbeet (Miller et 

al. 1994). More recently, POST applications of dimethenamid-P have 

been useful in providing residual control of emerging annual grasses 

and broadleaf weeds in sugarbeet (Rice et al. 2002). 

Cultivation and/or hand hoeing are used to complement herbicide 

weed control programs in sugarbeet. Sugarbeet fields are often cultivated 

one to three times during the growing season, with an additional one 

to three hand hoeing operations to control escaped weeds. Herbicide 

treatments used prior to hand hoeing have a dramatic effect on the 

amount of time required to hand hoe (Dawson 1974). Hand hoeing time 

is a function of weed density. Miller and Fornstrom (1989) reported 

that herbicides reduced early-season weed populations by 33 to 97% 

and hoeing times by 38 to 89% compared with an untreated control. 

Similarly, herbicide treatments reduced mid-season weed populations 

by 48 to 97% and hoeing time by 48 to 88% compared with an untreated 

control in the same study. Over time, there has been an increased cost 

associated with contract hand labor for weed control in sugarbeet which 

has resulted in less labor and more use of herbicides and cultivation. 

Despite the increased cost, hand labor remains an important tool in 

sugarbeet weed management. 

The objectives of this study were to evaluate several herbicide 

programs for weed control and yield in sugarbeet, and to determine the 

most economical herbicide program with and without hand labor. 


Field experiments were conducted at the University of Wyoming 

Torrington Research and Extension Center (TREC) in 2004, and the 

James C. Hageman Sustainable Agriculture Research and Extension


Center (SAREC) near Lingle, Wyoming in 2005 to evaluate several 

herbicide programs with and without hand hoeing for weed control in 

sugarbeet. The soil type at TREC was a Valentine fine sand (Mixed, 

mesic Typic Ustipsamments), and a Haverson loam (Fine-loamy, 

mixed, superactive, calcareous, mesic Aridic Ustifluvents) at SAREC. 

Soil organic matter and pH at TREC was 1.1 % and 7.8, and 1.3% and 

7.9 at SAREC. Sugarbeet cultivar ‘Beta 4546’ was planted to stand at 

a seed spacing of 20 cm in 76 cm rows at a seeding rate of 168,000 

seeds/ha on April 15, 2004 and April 18, 2005. The plots were sprinkler 

irrigated at both locations. Predominant weed species at both sites were 

common lambsquarters and green foxtail. 

The experimental design was a randomized complete block with a 

split-plot arrangement and four replications. The main plots consisted 

of 20 herbicide treatments plus an untreated control, and the subplots 

consisted of the presence or absence of hand hoeing. Split plots were 

3 m wide by 7.6 m long. Herbicide treatments were applied broadcast 

with a CO 2 pressurized knapsack sprayer delivering 180 L/ha at a pressure 

of 276 kPa and a walking speed of 5 km/hour. Herbicide treatments 

and rates are listed in Table 1. Ethofumesate was applied preplant incorporated 

(PPI). Two over-the-top applications of the standard-split rate 

were made when sugarbeet was at 2- and 4-true leaf stages of development. 

Three over-the-top applications of the standard-split rate were 

made when sugarbeet was at 2-, 4-, and 6-true leaf stages. Three overthe-top 

applications of the micro-rate were made when sugarbeet was at 

cotyledon, 2-, and 4-true leaf stages. Four over-the-top applications of 

the micro-rate were made when sugarbeet was at cotyledon, 2-, 4-, and 

6-true leaf stages. Dimethenamid-P and clethodim were applied overthe-top 

in combination with the standard-split and micro-rate herbicide 

programs at the 6-true leaf stage of sugarbeet. 

Weed control was assessed by weed species counts at both locations 

14 days after the final herbicide application. Weed density was 

determined by counting two randomly selected areas 3 m long and 

0.15 m wide in the middle two rows of each plot. Weed control was 

calculated by dividing the number of weeds in each plot by the number 

of weeds in the untreated control. Whole plots were split into two 

equal halves length-wise and half of each plot was hand hoed using 

long handle hoes. Hand hoeing was timed and was included in the 

economic analysis. The center row in each plot was harvested for yield 

using a single row sugarbeet lifter, weighed, and a sub-sample pulled 

for quality analysis at the Western Sugar Tare Laboratory at Scottsbluff, 

Nebraska. 

For economic comparison, variable costs associated with weed


Table 1. Treatments, herbicides and herbicide rates at both TREC and SAREC locations. 

Treatment † herbicides ‡ Rates § 

PPI fb Standard (×2) ETH fb PDE + TRI fb PDE + CLOP 1.12 fb 0.28 + 0.018 fb 0.37 + 0.11 

PPI fb Standard (×3) ETH fb PDE + TRI fb PDE + CLOP fb PDE 1.12 fb 0.28 + 0.018 fb 0.37 + 0.11 fb 0.37 

PPI fb Micro-rate (×3) ETH fb PDE + TRI + CLOP 1.12 fb 0.09 + 0.004 + 0.02 

PPI fb Micro-rate (×4) ETH fb PDE + TRI + CLOP 1.12 fb 0.09 + 0.004 + 0.02 

PPI fb Standard (×2) fb dimethenamid-P ETH fb PDE + TRI fb PDE + CLOP fb DIM 1.12 fb 0.28 + 0.018 fb 0.37 + 0.11 fb 0.81 

PPI fb Standard (×3) + dimethenamid-P ETH fb PDE + TRI fb PDE + CLOP fb PDE + DIM 1.12 fb 0.28 + 0.018 fb 0.37 + 0.11 fb 0.37 + 0.81 

PPI fb Micro-rate (×3) fb dimethenamid-P ETH fb PDE + TRI + CLOP fb DIM 1.12 fb 0.09 + 0.004 + 0.02 fb 0.81 

PPI fb Micro-rate (×4) + dimethenamid-P ETH fb PDE + TRI + CLOP + DIM 1.12 fb 0.09 + 0.004 + 0.02 + 0.81 

Standard (×2) PDE + TRI fb PDE + CLOP 0.28 + 0.018 fb 0.37 + 0.11 

Standard (×3) PDE + TRI fb PDE + CLOP fb PDE 0.28 + 0.018 fb 0.37 + 0.11 fb 0.37 

Micro-rate (×3) PDE + TRI + CLOP 0.09 + 0.004 + 0.02 

Micro-rate (×4) PDE + TRI + CLOP 0.09 + 0.004 + 0.02 

Standard (×2) + clethodim PDE + TRI fb PDE + CLOP + CLE 0.28 + 0.018 fb 0.37 + 0.11 + 0.09 

Standard (×3) + clethodim PDE + TRI fb PDE + CLOP fb PDE + CLE 0.28 + 0.018 fb 0.37 + 0.11 fb 0.37 + 0.09 

Micro-rate (×3) + clethodim PDE + TRI + CLOP fb PDE + TRI + CLOP + CLE 0.09 + 0.004 + 0.02 fb 0.09 + 0.004 + 0.02 + 0.09 

Micro-rate (×4) + clethodim PDE + TRI + CLOP fb PDE + TRI + CLOP + CLE 0.09 + 0.004 + 0.02 fb 0.09 + 0.004 + 0.02 + 0.09 

Standard (×2) fb dimethenamid-P PDE + TRI fb PDE + CLOP fb DIM 0.28 + 0.018 fb 0.37 + 0.11 fb 0.81 

Standard (×3) + dimethenamid-P PDE + TRI fb PDE + CLOP fb PDE + DIM 0.28 + 0.018 fb 0.37 + 0.11 fb 0.37 + 0.81 

Micro-rate (×3) fb dimethenamid-P PDE + TRI + CLOP fb DIM 0.09 + 0.004 + 0.02 fb 0.81 

Micro-rate (×4) + dimethenamid-P PDE + TRI + CLOP fb PDE + TRI + CLOP + DIM 0.09 + 0.004 + 0.02 fb 0.09 + 0.004 + 0.02 + 0.81 

† Standard (×2), 2 standard-split rate treatment applications; Standard (×3), 3 standard-split rate treatment applications; Micro-rate (×3), 3 

micro-rate treatment applications; Micro-rate (×4), 4 micro-rate treatment applications; PPI, preplant incorporated ethofumesate application. 

All micro-rate treatments included MSO at 1% v/v. 

‡ Abbreviation: ETH, ethofumesate; PDE, Phenmedipham + Desmedipham + Ethofumesate; TRI, triflusulfuron; CLOP, clopyralid; DIM, 

dimethenamid-P; CLE, clethodim; fb, followed by. 

§ Rates given in kg ai/ha.


control including herbicides, herbicide application, and hand labor were 

calculated. All other factors such as seed, fuel, equipment, land, and 

cultivation costs were constant in each treatment and were not included 

in the analysis. Gross returns were calculated for each plot on the basis 

of the Western Sugar grower contract payment schedule. Price per ton 

was dependent on sucrose content and average price of sugar from the 

payment schedule. Adjustment of tare was incorporated into the calculations 

to more accurately reflect the payment a grower would receive. 

The herbicide costs were derived from data compiled by the University 

of Nebraska Cooperative Extension (UNCE 2004, 2005), herbicide 

application cost was set at a rate of $9.88/ha and hand labor costs at a 

rate of $7.50/hr. The net return was the economic return on investment 

in weed control. 

Data were analyzed as a mixed model and subjected to ANOVA 

using the PROC MIXED procedure of SAS (SAS 2003) and means 

separated using Fisher’s Protected LSD (α = 0.05). Herbicide treatment, 

hand hoeing, and the interaction between these factors were analyzed 

as fixed effects and location was included as a random effect. Since 

there was no location by treatment interaction, data from TREC and 

SAREC were combined. Main effects of herbicide treatment and hand 

hoeing are presented because treatment by hand hoeing interaction was 

not significant. Single degree of freedom linear contrasts were used to 

compare groups of different herbicide treatments with respect to weed 

control, yield, and economic returns. 

ReSuLTS AnD DISCuSSIon 

Weed control 

There was no herbicide treatment by location interaction with respect to 

weed control, so treatment data were averaged over locations for analysis. 

Common lambsquarters control ranged from 60 to 100% (Table 2). 

PPI ethofumesate followed by standard-split or micro-rate treatments 

provided excellent control of common lambsquarters (97 to100%) with 

the exception of the treatment that included three micro-rate applications, 

which provided only 85% control. Micro-rate treatments applied 

alone or in combination with clethodim or dimethenamid-P controlled 

common lambsquarters 60 to 80% (Table 2). Layby application of dimethenamid-P 

with the micro-rate program alone did not improve common 

lambsquarters control when compared with the micro-rate program that 

included PPI. Combinations of the micro-rate program with clethodim 

decreased common lambsquarters control when compared with combinations 

of clethodim with the standard-split rates. The reduction in


Table 2. Effect of herbicide treatments on the control of common lambsquarters and green foxtail, and hoeing time averaged 

over TREC and SAREC locations. 

Weed control ‡ 

Treatment † Common lambsquarters Green foxtail hand hoeing time § 

------------------------------ % ------------------------------ h/ha 

PPI fb Standard (×2) 99 100 4.07 

PPI fb Standard (×3) 100 100 4.87 

PPI fb Micro-rate (×3) 85 99 4.78 

PPI fb Micro-rate (×4) 98 100 3.63 

PPI fb Standard (×2) fb Layby 99 100 3.02 

PPI fb Standard (×3) fb Layby 99 100 2.95 

PPI fb Micro-rate (×3) fb Layby 99 100 3.81 

PPI fb Micro-rate (×4) fb Layby 97 100 3.27 

Standard (×2) 83 65 6.56 

Standard (×3) 94 95 9.09 

Micro-rate (×3) 60 65 9.15 

Micro-rate (×4) 71 97 6.13 

Standard (×2) + Grass 94 100 7.88 

Standard (×3) + Grass 91 98 5.02 

Micro-rate (×3) + Grass 63 94 7.85 

Micro-rate (×4) + Grass 80 98 6.75 

Standard (×2) fb Layby 93 83 6.19 

Standard (×3) fb Layby 97 98 4.37 

Micro-rate (×3) fb Layby 64 80 7.37 

Micro-rate (×4) fb Layby 73 100 5.83 

Weedy check 0 0 22.66 

LSD (0.05) 21 16 5.35 

† Herbicide treatments applied at cotyledon to 2-leaf stage of sugarbeet with sequential treatments applied 7 days between applications. 

‡ Weed populations were counted at both locations 14 days after the final herbicide treatment. Percentage weed control was calculated by dividing the 

number of weeds in each plot by the number of weeds in the weedy check. 

§ Hand hoeing time after herbicide treatment application.


control of common lambsquarters was probably due to reduced rates of 

phenylcarbamate herbicides used in the micro-rate treatments and not 

antagonism between the tank-mix of these herbicides with clethodim. 

Antagonism from the tank-mix of phenmedipham and desmedipham 

with clethodim has been reported in grass and not in broadleaf weed 

control (Dexter and Luecke 1995). 

Single degree of freedom contrasts were conducted to determine 

if there were differences in weed control with the different herbicide 

programs (Table 3). There was no benefit to increasing the number of 

standard-split applications from 2 to 3 for common lambsquarters control. 

However, common lambsquarters control was improved by 6% 

when the number of micro-rate applications was increased from 3 to 4. 

The total amount of herbicide active ingredient applied per hectare for 

the standard-split treatments was higher than for the micro-rate treatments. 

The lower number of standard-split application did not result in 

as great a reduction in the amount of active ingredient applied per hectare 

when compared with the micro-rate treatments. This may explain 

the differences observed in control of common lambsquarters with the 

equal number of applications between the standard-split and micro-rate 

herbicide treatments. Standard-split treatments provided 16% greater 

control of common lambsquarters compared with the micro-rate treatments 

supporting the benefits of increased herbicide rates for management 

of this weed species. Use of PPI ethofumesate increased common 

lambsquarters control by 17% when compared with treatments where 

ethofumesate was not applied. Similar results were reported by Miller 

and Fornstrom (1989), where a PPI application of ethofumesate followed 

by POST herbicides were more effective than POST herbicides 

applied alone. 

Green foxtail control ranged from 65 to 100% with the various herbicide 

treatments (Table 2). All treatment combinations provided more than 

80% control of green foxtail, with the exception of 2 or 3 applications 

of the standard-split and micro-rate treatments, respectively, when PPI 

ethofumesate or layby dimethenamid-P was applied. Significant improvements 

in the control of green foxtail occurred with the increased application 

frequency of both the standard-split and micro-rate treatments, ethofumesate 

PPI, and the inclusion of clethodim as a POST treatment (Table 

2). Combinations of two standard-split and three micro-rate treatments 

with layby application of dimethenamid-P did not improve green foxtail 

control when compared with combinations of these treatments with 

clethodim. Standard-split treatments and micro-rate treatments were not 

different in the control of green foxtail (Table 3). When PPI ethofumesate 

or POST clethodim was included in the herbicide program green foxtail


control was improved by at least 5%. 

The effectiveness of different herbicide treatments in determining 

hand hoeing time is shown in Table 2. Treatments that were less 

effective in controlling weeds required longer periods of time for hand 

hoeing. These treatments reduced weed populations, thereby resulting 

in reduced hoeing times. These studies illustrate that acceptable levels 

of common lambsquarters and green foxtail control in sugarbeet production 

can be achieved by increasing herbicide inputs, either through 

preplant followed by sequential POST treatments, increased frequency 

of POST applications, increased rates of POST herbicides, hand hoeing 

or a combination of the above. 

Sugarbeet yield 

No herbicide treatment by location interaction was present with respect 

to sugarbeet yield, so herbicide treatment data were averaged over locations 

for analysis. Sugarbeet root yield was closely related to weed 

control. Root yield and extractable sucrose yield ranged from 25 to 

51 Mg/ha and 4 to 9 Mg/ha, respectively (Table 4). Ethofumesate PPI 

followed by four applications of the micro-rate treatment resulted in 

higher root and extractable sucrose yields compared with three microrate 

applications alone. Herbicide treatments did not influence sucrose 

concentration. 

Root and extractable sucrose yields were similar when application 

frequency increased either in the standard or micro-rate treatments 

(Table 5). Root and extractable sucrose yield were 7 and 1 Mg/ha great- 

Table 3. Herbicide program differences in weed control averaged over 

TREC and SAREC locations. 

Common lambsquarters Green foxtail 

Comparison † Difference p>|t| Difference p>|t| 

% % 

Standard (×2) vs. Standard (×3) -2 0.4267 -6 0.0006 

Micro-rate (×3) vs. Micro-rate (×4) -6 0.0041 -7 0.0001 

Standard vs. Micro-rate 16 0.0001 1 0.7108 

PPI vs. No PPI 17 0.0001 10 0.0001 

Layby vs. No Layby 5 0.0323 2 0.2012 

Grass vs. No Grass -6 0.0406 5 0.0230 

† Single degree of freedom contrasts comparing differences between herbicide 

programs (average of all treatments that contained the herbicide program). 

PPI, all treatments that contained preplant incorporated ethofumesate; 

Layby, all treatments that contained dimethenamid-P; Grass, all treatments 

that contained clethodim.


Table 4. Sugarbeet root yield, extractable sucrose, and net economic return as affected by weed control treatment averaged 

over TREC and SAREC locations. 

Treatment Root yield extractable sucrose net return † 

Mg/ha Mg/ha $/ha 

PPI fb Standard (×2) 48.1 7.9 1663 

PPI fb Standard (×3) 45.8 7.5 1531 

PPI fb Micro-rate (×3) 46.6 7.7 1668 

PPI fb Micro-rate (×4) 42.0 6.8 1385 

PPI fb Standard (×2) fb Layby 46.7 7.7 1590 

PPI fb Standard (×3) fb Layby 47.9 7.9 1579 

PPI fb Micro-rate (×3) fb Layby 50.8 8.3 1759 

PPI fb Micro-rate (×4) fb Layby 49.2 8.1 1681 

Standard (×2) 37.7 6.3 1350 

Standard (×3) 43.7 7.3 1468 

Micro-rate (×3) 33.6 5.4 1122 

Micro-rate (×4) 37.5 6.4 1383 

Standard (×2) + Grass 42.3 6.9 1451 

Standard (×3) + Grass 45.8 7.7 1572 

Micro-rate (×3) + Grass 36.2 6.1 1298 

Micro-rate (×4) + Grass 42.6 6.9 1492 

Standard (×2) fb Layby 41.9 6.9 1455 

Standard (×3) fb Layby 47.0 7.6 1587 

Micro-rate (×3) fb Layby 32.7 5.4 1103 

Micro-rate (×4) fb Layby 40.8 6.8 1424 

Weedy check 24.6 4.0 799 

LSD (0.05) 14.4 2.4 589 

† Net return was economic return on investment on weed control. Variable costs associated with weed control included herbicide, herbicide application, 

and hand labor. Herbicide costs were based on prevailing prices at both locations. Herbicide application cost was based on a rate of 

$9.88/ha, and hoeing costs were based on labor rate of $7.50/hr.


Table 5. Herbicide program differences in root yield, extractable sucrose, and net economic return averaged over TREC and 

SAREC locations. 

Root yield extractable sucrose net return 

Comparison † Difference p>|t| Difference p>|t| Difference p>|t| 


Standard (×2) vs. Standard (×3) -1.67 0.1702 -0.28 0.1627 -28.26 0.5510 

Micro-rate (×3) vs. Micro-rate (×4) -1.52 0.2142 -0.26 0.1947 -51.93 0.2811 

Standard vs. Micro-rate 3.48 0.0197 0.58 0.0174 -92.95 0.1004 

PPI vs. No PPI 6.97 0.0002 1.10 0.0002 214.92 0.0018 

Layby vs. No Layby 2.81 0.0563 0.45 0.0619 73.72 0.1908 

Grass vs. No Grass -1.52 0.3712 -0.27 0.4155 -31.59 0.6382 

† Single degree of freedom contrasts comparing differences between herbicide programs (Average of all treatments that contained the 

herbicide program). PPI, all treatments that contained preplant incorporated ethofumesate; Layby, all treatments that contained dimethenamid-P; 

Grass, all treatments that contained clethodim.


er, respectively, in treatments that received ethofumesate PPI compared 

with those that did not receive ethofumesate PPI. A similar trend was 

evident with standard-split treatments compared with micro-rate treatments, 

with standard-split treatments resulting in increased root and 

extractable sucrose yields. These differences suggest obvious yield benefits 

from increased weed control provided by higher herbicide inputs 

either in the form of preplant herbicides or higher POST herbicide rates. 

Additionally, sugarbeet yields were improved by sequential application 

of dimethenamid-P as a layby treatment, although this was only marginally 

significant. Clethodim did not result in a significant yield increase 

when compared with treatments where clethodim was not applied. 

There was not a hand hoeing by herbicide treatment interaction, 

so data were combined over herbicide treatments for analysis. Hand 

hoeing resulted in higher root and extractable sucrose yields compared 

with non-hand hoed plots; however, it had no effect on the sucrose content 

(Table 6). Hand hoeing was important in preventing yield losses 

from weed competition. These results are similar to those of Wicks 

and Wilson (1983), who found that sugarbeet root yields were highest 

in hand hoed plots and lowest in non-hand hoed plots. This suggests 

that hand hoeing can be an effective supplement to herbicides for weed 

control in sugarbeet especially for removal of large weeds that escape 

herbicide applications. 

eConoMIC AnALYSIS 

Herbicide input costs varied among the treatments. Net returns 

ranged from $799 to $1759/ha. High weed pressure requires effective 

herbicide efficacy to optimize net production returns. Increased 

POST application frequency for the standard-split rate or micro-rate 

programs were not different from the lower number of POST appli- 

Table 6. Sugarbeet root yield, extractable sucrose yield, and net return as 

influenced by hand hoeing averaged over TREC and SAREC locations. 

Treatment † Root yield extractable sucrose net return 


Hand hoeing 45.87a ‡ 7.64a‡ 1606.92a ‡ 

No hand hoeing 38.28b 6.24b 1283.96b 

† Means of all treatments with hand hoeing or no hand hoeing applied after 

herbicide treatment application. 

‡ Least square means within a column followed by the same letter are not 

significantly different (α= 0.05).


cations with regard to net return (Table 5). Standard-split rate POST 

applications resulted in $93/ha greater net return than the micro-rate 

program; however, this difference was not significant. Treatments 

including ethofumesate PPI resulted in $215/ha increase in net return 

compared with treatments where ethofumesate PPI was not applied. 

Treatments that contained PPI applications of ethofumesate provided 

better weed control and resulted in higher root and extractable sucrose 

yields. Ethofumesate PPI reduced early-season weed competition 

which subsequently improved yields. The additional input cost of 

using ethofumesate PPI followed by either the standard-split rate or 

micro-rate program paid off with higher root and extractable sucrose 

yields resulting from better weed control. Weed infestation is the most 

important factor determining the most economical weed management 

program in sugarbeet production. Heavy weed pressure can be controlled 

with preplant herbicides such as ethofumesate in combination 

with POST standard-split rate or micro-rate applications. Standard-split 

rate applications had higher input costs but resulted in better economic 

returns because of better weed control which resulted in higher root and 

extractable sucrose yields. 

Net returns were increased by over $300/ha from hand hoeing 

compared with treatments that were not hand hoed (Table 6). The 

additional cost associated with hand hoeing was offset by higher yields 

which resulted in higher net returns on investment. High weed pressures 

provide the highest benefit for hand hoeing while at low weed densities 

the decision to hoe must be based on future weed pressure and expected 

economic returns (Miller and Fornstrom 1989). Hand hoeing was 

important even with higher herbicide inputs especially for management 

of weed escapes late in the season. As sugarbeet growers design weed 

control programs, they should consider pressure from weeds which 

escape herbicide control before using supplemental hand hoeing. 

Treatments that provided good weed control and resulted in high 

root and extractable sucrose yields performed well economically. Weed 

species such as common lambsquarters can be controlled with preplant 

herbicides such as ethofumesate that reduce early-season weed competition 

in combination with POST standard-split rate or micro-rate 

applications. The cost of a PPI application of ethofumesate was more 

than offset by the increased yield that resulted.



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