Seed Treatment and Surface Application of Insecticides for Suppression of Megacopta cribraria in Soybean, 2013 * Open Access

An experiment was conducted at the UGA Southeastern Branch Research and Education Center near Midville, GA, to evaluate various rates of neonicotinoid seed treatment for efficacy on Megacopta cribraria F. (Mc) in seedling soybean. Raw soybean (G03-1187-RR [AGS 787 RR]) seed was treated using a Hege, centrifugal, seed-treating machine on 24 Apr. Neonicotinoid formulations were diluted in water prior to application on seed. Seed was planted 5 May using a cone planter at 8 seed/ft. Plots were 2 rows 20 ft long and 36 inches apart with 6 ft alleys arranged in RCB design with six replicates. In certain plots, Lorsban granules were applied in a 7-inch band over the row followed by incorporation into the soil. On 13 and 27 Jun, all plants in one row of each plot were examined for Mc and recorded as either a single adult/plant or aggregated adults (5 or more insects)/plant. On 13 Jun, the soil beneath plants of one row of each plot was examined for Mc cadavers. Yield was determined by harvesting all plants in each plot with a Hege plot combine on 4 Nov. The statistical analysis was ANOVA with Tukey’s mean separation ( P  < 0.05) as per Agriculture Research Management 8 statistical software.

The purpose of the test was to determine whether a neonicotinoid seed treatment could suppress Mc populations on seedlings, recognizing that certain of the neonicotinoid rates were higher than economically feasible for soybean. Previous observations of Mc cadavers next to soybean seedlings planted with commercial seed treatment using neonicotinoids indicated that the insecticide had lethal effects on Mc within 45 d after planting. However, the commercial seed treatments did not seem to reduce the numbers of live Mc on the plants as compared to seedlings which had not received insecticide treatment on seed. In the current test, at 34 d after planting, Mc cadavers were found in certain plots treated with Cruiser, Gaucho, and Poncho. However, Mc populations (live Mc adults per plant) were higher in all the insecticide treatments as compared to the untreated check on both 34 and 47 d after planting ( Table 1 ). Yield was similar in all the treatments.

Author notes