Velvetbean Caterpillar and Green Cloverworm Control on Soybean with <u>Bacillus Thuringiensis</u>, 1983

Soybeans, Braxton variety, were planted in 36-in. rows at the Brewton Experimental Farm, Brewton, Ala., in June. Treatment plots were four rows x 50 ft arranged in a randomized complete block design with four replications. Treatments were applied with a CO2 pressurized, hand carried sprayer delivering 14.7 gal/acre through three TX6 nozzles per row at 30 lb/in2 . Applications were made on 9 Sep. when combined velvetbean caterpillar (VBC) - green cloverworm (GCW) populations had reached economic threshold levels. Prespray evaluations were made on 9 Sep. by taking a 6-ft shake cloth sample from each plot. Postspray evaluations were made on 14 and 19 Sep. by taking two 6-ft samples per plot. Larvae were recorded as small (1st and 2nd instar), medium (3rd and 4th instar), and large (5th and 6th instar, prepupae). Treatment means for each size class per species and combined species totals were calculated. Numbers of small VBC and GWC larvae were combined because of the difficulty in distinguishing between the small larvae of these species in the field.