Soybean Aphid & Seed Treatment Updates Heading into 2005

1. Soybean Aphid & Seed TreatmentUpdates Heading into 2005 Eileen Cullen UW Madison, Entomology Department

2. Seed Treatments for Soybean Cruiser 5FS thiamethoxam nicotinoid Syngenta Yes ‘early season protection’ SBA, BLB, wireworm, maggot Gaucho imidacloprid nicotinoid Bayer CropSci No Active ingredient Chemistry Company EPA Reg? Insects

3. Supplemental Label Registration Dec. 2004 Cruiser® 5FS Seed Treatment Potatoes and Soybeans For Soybeans Active ingredient (a.i.)thiamethoxam Rate 1.28 fl oz per 100 lbs. of seed [50 g a.i./100Kg seed] “to provide early season protection of seedlings against injury by aphids, bean leaf beetle, Mexican bean beetle, pea leaf weevil, pea weevil, plant leaf hopper, seed corn maggot, thrips and wireworm”

4. Figure from recently released promotional material for CruiserMaxx Pak (Cruiser 50g ai/100 kg seed + ApronMaxx) 250 SBA/Plant

5. Figure from recently released promotional material for CruiserMaxx Pak (Cruiser 50g ai/100 kg seed + ApronMaxx) 250 SBA/Plant Planting date? 9 June

7. CruiserMaxxPak promotional material • omitted late planting date [June 9th] • when presenting the UW 2003 trial. • Why Late Planted? • Spring 2003, prior to soybean aphid outbreak, • late planting was done to obtain insecticide • efficacy data. [2000-2002 trend observed that • late planted fields tended to be hit harder • by soybean aphid – good chance to obtain • efficacy data].

8. Trial 2 Trial 1 Planted: June 9 Harvest: Oct 16 Cultivar: NK S24-K4 Plots: 10’ w x 25’ l 30-inch rows CRBD: 4 replicates Planted: June 9 Harvest: Oct 16 Cultivar: NK S19-V2 Plots: 10’ w x 25’ l 30-inch rows CRBD: 4 replicates Poncho 62.5 g a.i./100 Kg seed Poncho 125 g a.i./100 Kg seed Gaucho 62.5 g a.i./100 Kg seed Cruiser 62.5 g a.i./100 Kg seed CHECK Cruiser 30 g a.i./100 Kg seed Cruiser 50 g a.i./100 Kg seed Gaucho 62.5 g a.i./100 Kg seed CHECK UW 2003 Seed Treatment TrialsSoybean Aphid

9. This trial featured in CruiserMaxx Pak brochure 62.5 Aphids/ plant 250 Aphids/Plant May June Late planted June 9th, up to 30+ days later than typical May planting dates Sample Date Soybean Aphid Seed Treatment Trial 1, Arlington WI 2003. Planted Late June 9th. Mean Aphids/Plant by sampling date

10. Soybean [aphid] seed treatment trial 1, Arlington WI 2003 Yield (bu/A) by Treatment. (P = 0.002; F = 6.59; df, 5) Means followed a different letter are significantly different at  = 0.05

11. In a second UW 2003 seed treatment trial, soybean aphid density exceeded 250 aphids/plant by August 13th. -Same planting date (June 9th) -Cruiser rate of 62.5 g a.i./100 Kg seed -higher rate than CruiserMaxx Pak 50g -still exceeded 250 aphids/plant

12. Cruiser 62.5 g exceeded threshold, even at late planting 62.5 62.5 250 Aphids/Plant Soybean Aphid Seed Treatment Trial 2, Arlington WI 2003. Planted Late June 9th. Mean Aphids/Plant by sampling date Aphids/ plant June May Sample Date

13. Soybean [aphid] seed treatment trial 2,Arlington WI 2003 Yield (bu/A) by Treatment. (P = 0.1151; F = 2.33; df, 4) Means followed a different letter are significantly different at  = 0.05

14. Percent Mortality (%) + SEM Days after planting • Lab bioassay [Univ/ of Minnesota] • aphids placed on leaves from • thiamethoxam-treated plants • - mortality after 24 & 48 hours University of Minnesota, 2003, 2004 preliminary data, D. W. Ragsdale and B. P. McCornack. Not for distribution or publication. This slide may not be reproduced or redistributed without permission from the authors. Percent Mortality (%) + SEM Days after planting Mortality lasts for 35 days ~ V3/V4 plant stage (Adapted from Ragsdale and McCornack 2004)

15. 24 h 48 h * Untreated Control * * * Nymphs Deposited + SEM Cruiser 50g/100Kg (thiamethoxam) * * Days after planting Lab bioassay for fecundity,U of MN University of Minnesota, 2004 preliminary data, D. W. Ragsdale and B. P. McCornack. Not for distribution or publication. This slide may not be reproduced or redistributed without permission from the authors. thiamethoxam reduced aphid fecundity, up to ~V4 (= the number of nymphs produced) (Adapted from Ragsdale and McCornack 2004)

16. From the Cruiser label: “Early season protection” From the Cruiser web page: “The early-season pests, which suck and chew on the crop during its most vulnerable and tasty phase (the first 30 to 40 days of growth) are intoxicated when they try to feed on the treated crops.” Chris DiFonzo, Michigan State University

17. Bottom line: • Seed treatments provide early-season protection • Seed treatments may fit well in production areas w/ early-season insect problems (for ex. BLB) • Seed treatments ALONE may not be enough under high, or late season, SBA pressure • In fields lacking early-season pests, a well- timed foliar spray, based on aphid scouting & threshold, is the recommended practice for optimal yield protection. Midwest University Extension Entomologists’ Consensus Recommendation

18. Eileen Cullen UW Madison Entomology Department Extension Entomologist University of Wisconsin Entomology Department 1630 Linden Drive Madison, WI 53706 Tel: (608) 261-1507 E-mail: cullen@entomology.wisc.edu