Vol. 54â2000 - NorthEastern Weed Science Society
Vol. 54â2000 - NorthEastern Weed Science Society Vol. 54â2000 - NorthEastern Weed Science Society
TIMING OF GLYPHOSATE APPLICATION FOR PERENNIAL WEED CONTROL IN SOYBEANS .,. . .... , A. Cooper, M. VanGessel, and C. Whaley' ABSTRACT Optimum weed control and yield can be achieved with one application of glyphosate applied to glyphosate-resistant soybean (Glycine max) during the third to fourth week after planting. However, this research has been conducted with annual weed species. The optimum time to treat perennial weeds has not been determined. Most perennials are most sensitive during late-vegetative or earty-reproductive stages. Waiting until these later stages can impact herbicide coverage, reducing weed control, as well as reducing yield due to earty-season weed competition. Studies were conducted in 1998 and 1999 to determine Canada thistle (Cirsium arvense) or horsenettle (Solanum carolinense) control when glyphosate was applied at 3, 4, 5, or 6 weeks after planting CNAP). Glyphosate-resistant soybeans were planted in 38 em rows. Glyphosate rate was 1.0 Ibs aUA. Furthermore, at 5 WAP glyphosate applied at 0.75 and 1.51bs aUA. Finally, sequential glyphosete applications at 1 Ib aUA were applied at 4 and 6 WAP. In 1998, Canada thistle control was best with an application at 6 WAP or the sequential application of 4 and 6 WAP. A definite trend for later applications improving control was observed. Horsenettle control in 1998 and 1999 was similar for applications at 4, 5 or 6 WAP. The 0.751b aUA rete provided similar level of control as the higher rates. Effective perennial weed control requires an aggressive long-term approach. These plots will be followed until the following spring to determine if an in-crop glyphosate application can be an effective long-term tool for Canada thistle or horse nettle control. 'Res. Assoc., Assoc. Prof., and Grad. Student, University of Delaware, Georgetown, DE. . 2
EFFECT OF HERBICIDE RATES AND IRRIGATION TIMING ON WEED CONTROL IN IRRIGATED CORN Sujatha Sankula' and Mark J. VanGessel ABSTRACT Preemergenceherbicidetreatmentsrequirerainfallto move/incorporatethe herbicideinto the soil where it is available for uptake by germinating weed seedlings. Information is limited on the timing of incorporation and appropriate rates of premix products. A simulated rainfall study wasconducted in 1999 as randomized complete block with factorial arrangement of three irrigationtimings andthreeuse ratesof a premixof metolachlor+ atrazine.Herbicideapplication was made afterplanting followed by irrigation either inunediately, 7 DAT, or 14 DAT. Herbicideswere appliedat 2.0, 2.5, or 3.2 kg ai/hathatrepresentuse ratesforcoarse,medium, or fine texturedsoils, respectively.Plots thatareto receiveirrigationat a particulartimingwere irrigatedwith 3 em of waterwhile the restof the plotsremainedcoveredwitha clearplasticof 4.2 m x 7.5 m. Evaluationson weed controlandweed countswere takenfroman areaof 1.5 m x 6 m from thecenter of each plot 4 WAT, 8 WAT, and prior to physiological maturity. Visual weedcontrolevaluationwas affectedbothby irrigationtimingandherbiciderateswhile, weed countswere influencedonly by irrigationtiming. Weedcontrolwas greaterby 5 to 15%when irrigation followed inunediately after herbicide application compared to the rest of the timings. No differenceswere found in weed controlwhenplots were irrigated7 or 14days afterherbicide application. Similarresultswere notedwithweed counts. The mid andhighratesof herbicides providedhigherlevel of weed controlcomparedto low rate. A parallelstudywas conductedatthreelocationsto evaluatethe use ratesof a premixof metolachlor+ atrazine with and-withoutsima:zinein irrigatedcom production.Design was a randomizedcompleteblock with factorialarrangementof treatments. Treatmentsincluded metoiachior + atrazine at 2.3, 2.8, 3.2, and 3.7 total kg ailha alone or with simazine at 1.1 kg aiIha.Comparisontreatmentswere establishedwith2.8 kglhaof metolachlor+ atrazine in combination with 1.4 kg/ha ofsimazine plus a weedy check. Except fur 2.3 kg/ha metolachior + atrazine appliedalone, no differenceswerenotedin pre-harvestweed controlandweed counts amongherbicidetreatmentsat all locations. No differencesweredetectedin final yield between treatments.This studyemphasizesthatadditionalresidualherbicideis not neededto increase weedcontrolif metolachlor+ atrazineis usedat 2.8 kg/haon coarsetexturedsoils. 'Post-Doctoral ResearchAssociate,Dept.of Plant andSoil Sciences,Universityof Delaware Research and Education Center (UDREC), Georgetown, DE 19947 3
- Page 1: WEED REMOVAL TIMING WITH ROUNDUP RE
- Page 5 and 6: 40 Effect of Pronone Applied with A
- Page 7 and 8: Comparisonof Sulfosateand Glyphosat
- Page 9 and 10: N 1175 feet Roundup Ready Studies R
- Page 11 and 12: VIRGINIA TECH'S ONLINE WEED IDENTIF
- Page 13 and 14: WEED CONTROL AND YIELD OF CUT FLOWE
- Page 15 and 16: Table I. Effect of napropamide and
- Page 17 and 18: The Effect of Total Postemergence H
- Page 19 and 20: with commercial fertilizer. In gene
- Page 21 and 22: HERBICIDE APPLICATIONS VERSUS HANDW
- Page 23 and 24: exceeded 4. The success of training
- Page 25 and 26: _u ____ Table2: Estimatesof herbace
- Page 27 and 28: DOUBLE CROP CORN WEED CONTROL IN VI
- Page 29 and 30: ANNUAL WEED AND GRASS CONTROL IN CO
- Page 31 and 32: MANAGING QUACKGRASSINFESTATIONSAS C
- Page 33 and 34: USING HERBICIDE RESISTANT HYBRIDS T
- Page 35 and 36: NICOSULFURONIRIMSULFURON COMBINATIO
- Page 37 and 38: GLYPHOSATE ALONE AND PRECEDED BY PR
- Page 39 and 40: ROUNDUPVS. LIBERTY:WHATHAVE WE LEAR
- Page 41 and 42: In summary, application timing for
- Page 43 and 44: INFLUENCE OF TIMING ON WEED MANAGEM
- Page 45 and 46: IMPACT OF GLYPHOSATE TIMING AND COR
- Page 47 and 48: PREEMERGENCE HERBICIDES INFLUENCE W
- Page 49 and 50: COMPARISON OF WEED CONTROL SYSTEMS
- Page 51 and 52: Table I Mean Percent Weed Control V
TIMING OF GLYPHOSATE APPLICATION FOR PERENNIAL WEED<br />
CONTROL IN SOYBEANS<br />
.,. . .... ,<br />
A. Cooper, M. VanGessel, and C. Whaley'<br />
ABSTRACT<br />
Optimum weed control and yield can be achieved with one application of glyphosate<br />
applied to glyphosate-resistant soybean (Glycine max) during the third to fourth week<br />
after planting. However, this research has been conducted with annual weed species.<br />
The optimum time to treat perennial weeds has not been determined. Most perennials<br />
are most sensitive during late-vegetative or earty-reproductive stages. Waiting until<br />
these later stages can impact herbicide coverage, reducing weed control, as well as<br />
reducing yield due to earty-season weed competition.<br />
Studies were conducted in 1998 and 1999 to determine Canada thistle (Cirsium<br />
arvense) or horsenettle (Solanum carolinense) control when glyphosate was applied at<br />
3, 4, 5, or 6 weeks after planting CNAP). Glyphosate-resistant soybeans were planted<br />
in 38 em rows. Glyphosate rate was 1.0 Ibs aUA. Furthermore, at 5 WAP glyphosate<br />
applied at 0.75 and 1.51bs aUA. Finally, sequential glyphosete applications at 1 Ib aUA<br />
were applied at 4 and 6 WAP.<br />
In 1998, Canada thistle control was best with an application at 6 WAP or the sequential<br />
application of 4 and 6 WAP. A definite trend for later applications improving control was<br />
observed.<br />
Horsenettle control in 1998 and 1999 was similar for applications at 4, 5 or 6 WAP. The<br />
0.751b aUA rete provided similar level of control as the higher rates.<br />
Effective perennial weed control requires an aggressive long-term approach. These<br />
plots will be followed until the following spring to determine if an in-crop glyphosate<br />
application can be an effective long-term tool for Canada thistle or horse nettle control.<br />
'Res. Assoc., Assoc. Prof., and Grad. Student, University of Delaware,<br />
Georgetown, DE. .<br />
2
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