Effects of biotic factors on stored potato quality - 2010 UWEX ...

<strong>Effects</strong> <strong>of</strong> Biotic Factors on StoredPotato QualityHancock Agricultural Experiment StationField DayRussell L. GrovesDepartment <strong>of</strong> EntomologyUniversity <strong>of</strong> Wisconsin1630 Linden DriveMadison, WI 53719groves@entomology.wisc.eduJuly 27, 2010

Potato virus Y‣ Positive sense RNA virus – Potyviridae‣ Transmitted by several aphid species in anon-persistent, non-circulative manner‣ Sequence <strong>of</strong> both transient and colonizing aphidspecies‣ Marketable yield loss inpotato seed production

PVY NPVY NPotato virus Y ComplexPVY OPVY NTNPVY OPVY NPVY OPVY O

Research Objectives‣ Investigate how the timing <strong>of</strong> PVY infection within thegrowing season and PVY strain (PVY O , and PVY N:O ) canaffect the efficiency <strong>of</strong> tuber infection and the resultinglong-term storability <strong>of</strong> harvested tubers.‣ Characterize and qualify the extent <strong>of</strong> storage qualitylosses associated with current-season infestations <strong>of</strong>key insect pests <strong>of</strong> potato (<strong>biotic</strong> <strong>factors</strong>) including thepotato leafhopper (and Colorado potato beetle).

PVY Field Study & Storage Trial,Hancock AES, 2008-09* RCBD (4 varieties, 2 inoculation times, and 2 PVY strains)1.) ‘Russet Burbank’, ‘Atlantic’, ‘Silverton Russet’, ‘Russet Norkotah’2.) Inoculation Time (pre-, & post-flower)3.) PVY strains (PVY O & PVY N:O4.) ‘Villetta Rose’ guard rows5.) DAS-ELISAN:O )* Storage: Processing (47 o F, 95% RH)Fresh Market (42 o F, 95% RH)* Quality Parameters (Harvest, 3, 6, 12, 18, 24, & 36 wks)1.) Tuber weights2.) Specific gravity3.) Sprouting4.) Internal defect (s)ExperimentalReplicate

PVY Impact(s) on Tuber Yield, 2008PotatoVarietyPVYStrainTuberSize (oz)TubersHill -1ProportionUnclassifiedUS (culls)Cwtac -1Atlantic O 5.2 ab 10.6 a 0.75 a 0.08 a 453 aN:OUTCMean Yield Estimates by Cultivar / Virus Strain 14.8 b 9.5 a 0.79 a 0.07 a 472 a5.6 a 10.5 a 0.81 a 0.07 a 501 aSilverton O 4.8 a 9.4 a 0.79 a 0.1 a 425 aRussetN:OUTC5.1 a 9.8 a 0.81 a 0.09 a 418 a5.1 a 9.9 a 0.80 a 0.11 a 439 aRusset O 5.1 a 9.8 a 0.85 a 0.07 a 476 aNorkotahN:OUTC5.1 a 9.9 a 0.86 a 0.05 a 467 a5.3 a 10.2 a 0.86 a 0.06 a 479 aRusset O 3.5 ab 13.8 a 0.72 a 0.13 a 408 bBurbankN:OUTC3.2 b 13.4 a 0.72 a 0.14 a 406 b3.7 a 14.3 a 0.73 a 0.14 a 489 a1 Means followed by the same letter in columns are not significantly different (P > 0.05; Fisher’s Protected LSD; n = 4)

Mean Specific GravityPVY Impact on Storage Quality:Specific Gravity / Percent Solids 2008-09091.091.08‘Silverton Russet’Non-inoculatedPVY OPVY N:OP=0.01911.071.061.051.041.036-Aug 14-Nov 22-Feb 1-Jun 9-SepSample Date

Mean Specific GravityPVY Impact on Storage Quality:Specific Gravity / Percent Solids 2008-09091.09‘Russet Burbank’1.081.071.06P=0.09331.051.04Non-inoculatedPVY OPVY N:O1.036-Aug 14-Nov 22-Feb 1-Jun 9-SepSample Date

17-Jun6-Aug25-Sep14-Nov3-Jan22-Feb12-Apr1-Jun21-Jul9-SepMean Proportion Weight Loss0.50.40.3PVY Impact on Storage Quality:Weight Loss / Shrinkage 2008-0909Non-inoculatedPVY O‘Silverton Russet’PVY N:OP

6-Aug25-Sep14-Nov3-Jan22-Feb12-Apr1-Jun21-Jul9-SepMean Proportion Weight LossPVY Impact on Storage Quality:Weight Loss / Shrinkage 2008-09090.50.4‘Russet Burbank’Non-inoculatedPhellem0.3PVY OPVY N:OCortical cellsP=0.03630.20.10Sample Date

Mean Sugars (mg/g FW)25-Aug14-Oct3-Dec22-Jan13-Mar2-MaySample DatePVY Impact on Storage Quality:Chemical Maturity 2009-101.21sucroseglucose‘Russet Burbank’0.80.6P=0.16930.40.20P=0.2740Non-inoculatedPVY

Research Objectives‣ Investigate how the timing <strong>of</strong> PVY infection within thegrowing season and PVY strain (PVY O , and PVY N:O ) canaffect the efficiency <strong>of</strong> tuber infection and the resultinglong-term storability <strong>of</strong> harvested tubers.‣ Characterize and qualify the extent <strong>of</strong> storage qualitylosses associated with current-season infestations <strong>of</strong>key insect pests <strong>of</strong> potato (<strong>biotic</strong> <strong>factors</strong>) including thepotato leafhopper (and Colorado potato beetle).

Insect Feeding – Potato Storage General threshold rules for potato leafhopper:If adult countper sweep is:then….< 0.5 treat only if > 0.1 nymphs/leaf0.5 - 1 treat if nymphs present and adultspresent for > 2 weeks1 - 1.5 treat immediately if nymphs present,or within 1 week if not present> 1.5 treat immediately

PLH Feeding Damage, Impacts inStoragePLH Damage in Potato‣ Document the impact <strong>of</strong> PLH feeding atdifferent thresholds among selectedcultivars in long-termstorage:(A) Exclusion (row cover)(B) At-threshold (>1.0 adult / sweep)(C) Above threshold (>2.5 adult / sweep)** Quality Parameters:1.) Tuber weights / weight loss2.) Specific gravity3.) Percent sugars4.) Internal defect (s)

Mean Specific GravityPLH Impact on Storage Quality:Specific Gravity / Percent Solids 2009-101.0781.0761.0741.072Un-infested‘Russet Burbank’At-thresholdthresholdAbove thresholdP=0.13201.071.0681.0661.0641.0621.066-Jul25-Aug14-Oct3-Dec22-Jan13-Mar2-May21-JunSample Date

Mean Specific GravityPLH Impact on Storage Quality:Specific Gravity / Percent Solids 2009-10‘Atlantic’1.08P=0.08941.0751.071.065Un-infestedAt-thresholdthreshold1.06Above threshold6-Jul25-Aug14-Oct3-Dec22-Jan13-Mar2-May21-JunSample Date

Mean Sugars (mg/g FW)25-Aug14-Oct3-Dec22-Jan13-Mar2-MaySample DatePLH Impact on Storage Quality:Chemical Maturity 2009-101.21sucroseglucose‘Russet Burbank’0.8P=0.39750.60.40.20P=0.5264UninfestedAt-thresholdthresholdAbove threshold

PVY & PLH Impact on Storage Quality:Summary 2008-10‣ In 2008-09, 09, significant quality losses in storage (percent solids & shrinkage)associated with current season infection <strong>of</strong> Potato virus Y.‣ Storage results in 2009-10, continued to reveal PVY quality losses (shrinkage),although no significant impacts on sugars were observed.‣ Trend towards storage impacts - PLH infestation- Low population densities – challenge to achieve lastinginfestation levels above established thresholds (2009).‣ Include both CPB and PLH in 2010-1111 storage studies

Co-authors & AcknowledgementsAlex Crockford 1Amy Charkowski 2AJ Bussan 3Andy Witherell 2Bob Coltman 4Rick Hafner 4and Kevin Bula 4Cooperative Extension 1 , Langlade County Agricultural Agent, Antigo, WIDepartments <strong>of</strong> Plant Pathology 2 and Horticulture 3 Madison, WIWisconsin Seed Potato Certification 4 , Antigo, WI