Evaluation of Dimilin and Benlate for Soybean Insect Pest and Disease Control, 1991
Abstract The experiment was conducted at the Texas A&M University Agricultural Research and Extension Center, Beaumont. The experimental design was a randomized complete block with 6 treatments and 4 replications. Soil type was a Midland silty clay loam. Plot size was 40 ft × 6 rows (32-inch row spacing). Plots were planted 4 Jun at about 10 seeds/ft. Immediately after planting, plots were treated with 2 pt Dual + 1 qt Roundup + % pt Scepter per acre. Soybeans emerged 10 Jun. On 16 Aug (when plants were R2—3 and insect pest populations were beginning to increase) treatments were applied to 4 rows of a plot using a Solo backpack sprayer. Finished spray volume was 20 gal/acre. Immediately before application and 5, 12, 21, 28, 35, and 42 d after this initial application, plots were sampled for insects. Each sample consisted of shaking soybean plants along 9 ft of row over a vertical beat sheet. Insects were shaken and brushed from the vertical beat sheet into a plastic bag which was frozen for later inspection of the contents. One sample (9 ft of sampled row) was taken in each plot on each sample date. On 9 Sep (when soybeans were R5) a second application of Benlate was made to all treatments with Benlate (thus, after all treatments were applied, treated plots were exposed to a single application of Dimilin and/or a double application of Benlate). On the same dates plots were sampled for insects, 15 leaflets (5 each from top, middle, and bottom third of canopy) were randomly removed from each plot and taken to a laboratory where estimates of % defoliation were recorded by comparing leaflets with templates of leaflets of known defoliation. From time of initial application to the last sample date 5.26 inches of rain was recorded. On 21 and 29 Oct plots were visually rated for cercospora leaf blight and anthracnose disease severity, respectively. At maturity 120 ft of row in each plot were harvested with a small plot combine. Yields were adjusted to 13% moisture. Insect count data were transformed using Vx + 0.5 and all data analyzed by ANOVA and means separated by DMRT.