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Arthropod Management Tests





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Soybean aphid, Aphis glycines Matsumura, has drastically changed soybean pest management in the North Central region. To date, SBA can be successfully managed by timely scouting and foliar insecticides. Host plant resistance is the newest soybean aphid management tool and is complementary to the existing chemical control. In 2014, we established plots at two Iowa State University Research Farms (Northeast and Northwest) on 24 May and 22 May, respectively. NK S25-E5 soybean variety was used for all the soybean aphid-susceptible treatments, and LD09-05484A soybean variety was used for the Rag1-containing treatments. Plots were arranged in an RCB design with four replications. Each plot was six rows in width and 50 ft in length. Treatments containing a seed treatment were applied by Syngenta. For the Northeast location, foliar treatments were applied using a backpack sprayer and TeeJet twinjet nozzles (TJ 11002) (Springfield, IL) with 20 gpa at 40 lb psi. Foliar applications were made on 22 Aug when plants were in the R5 growth stage. For the Northwest location, foliar treatments were applied using a custom sprayer and TeeJet flatfan nozzles (TJ 8002) (Springfield, IL) with 15.5 gpa at 40 lb psi. All foliar applications at this site were made 14 Aug when plants were in the R4 growth stage. Soybean aphids were counted on randomly selected whole plants within each plot. To estimate the total exposure of soybean plants to soybean aphid, we calculated cumulative aphid days (CAD) based on the number of aphids per plant counted on each sampling date. Yields (bushels/acre) were determined by weighing grain with a hopper and corrected to 13% moisture. One-way ANOVA was used to determine treatment effects within each experiment. Means separation for all studies was achieved using a least significant difference test (α = 0.10). All statistical analyses were performed using SAS software.


This article is from Arthropod Management Tests 40 (2015): F11, doi:10.1093/amt/tsv138. Posted with permission.


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