Colorado Potato Beetle Control with Natural Product Insecticides, 1990

Abstract

Abstract Certified B-size seed potatoes were planted 15 May at the University of Minnesota Agricultural Experiment Station, Crookston. Plots were 4 rows wide, 15.3 m (50 ft) long, with 91 cm (3 ft) spacing between rows and 30 cm (1 ft) spacing between plants. A completely randomized plot design with 3 replications was used. Plots were scouted daily for CPB egg masses beginning 20 Jun. When egg masses were found, they were flagged and checked daily for hatch. Timing of first spray application was at 30% hatch and subequent applications on a 7 d schedule. Plots were sprayed 3 times for each generation of CPB larvae: 28 Jun, 5 and 12 Jul for first generation and 25 Jul, 2, and 9 Aug for 2nd generation. Natural product insecticides used in this experiment were Bacillus thuringiensis var. san diego (MYX 1806), and B. thuringiensis var. tenebrionis (Trident) and neem (Margosan-O). Insecticidal sprays were applied using a tractor-mounted boom sprayer, with a single hollow cone nozzle over each row. Sprays were applied in 654 liters of water per ha (70 gal/acre) at 827 kPA (120 psi). Data were collected from the center 2 rows. Larvae were counted on 20 plants per plot. Data were expressed as mean number of larvae or plant injury (percent defoliation) × number of days elapsed, i.e., Area Under the Curve (AUC). AUC for CPB was computed separately for the first and second generation then summed. Two-way analysis of variance was used to test for treatment differences.