2004 Foliar
applied insecticide control of the Soybean Aphid (Aphis glycines).
Bruce Potter - IPM Specialist, University of Minnesota Southwest Research and Outreach Center
Summary
A soybean aphid insecticide efficacy trial was placed in a commercial soybean field near St. James, Watonwan County, MN. To rates of Asana XL, Baythroid, Lorsban 4E, Baythroid + Lorsban 4E, Mustang Max, Trimax and Warrior were evaluated. Additionally, Warrior was evaluated in combination with an anti-drift agent, non-ionic surfactant. The aphid population at this site began to increase relatively late (R4) and applications were made August 11, 2004 to R4.5 soybeans at 383 aphids/plant. The untreated plots accumulated over 3700 aphid days but populations remained below 300 aphids/plant for the duration of the trial. Yield differences between treatments were not observed. Lorsban 4E applications experienced the most rapid aphid decline. Pyrethroids required 6-14 days to reduce populations below those in plots not treated with insecticide. At 14 DAT, the treatments containing Lorsban 4E and Warrior had lower aphid populations. The 2.8 oz rate of Mustang Max and both Trimax treatment rates performed similarly to untreated. Other products were intermediate in performance. The addition of adjuvants did not affect performance of Warrior and the 2 oz rate of that product performed similarly to the 3.2 oz rate.
These
data suggest that low rates of insecticide may not provide adequate control
of soybean aphid and that soybean can tolerate a moderate aphid infestation
without yield loss.
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Created 11/24/04 by B. Potter with assistance from M. Werner.