Use of Bacillus Thuringiensis and Kryocide to Control Colorado Potato Beetle (CPB) in Potatoes, 1993

Potatoes were planted on 15 Apr at the Eastern Shore Agricultural Experiment Station, Painter, VA. Each plot consisted of a double 25 ft row, bordered on each side by an untreated guard row, and replicated 4 times in a randomized complete block design. Plant spacing was 10 inches with 36 inches between rows. Treatments were applied with a propane compressed gas backpack sprayer using three hollow cone (D4-45) nozzles/row and delivering 60 gal water/acre at 40 psi. Peak CPB egg hatch occurred on 17 May. Sprays were applied on 21, 31 May, 7 and 15 Jun. Cygon 400 (.25 lb Al/acre) was added to all treatments on 7 and 15 Jun to control potato leafhoppers. On 21 Jun, the entire test was sprayed out with Vydate L (2 qt product/acre) in order to prevent complete defoliation by emerging, first generation CPB adults. Rainfall from Mar until the second week in Jun resulted in a delayed planting date and difficulty in applying the critical, early season sprays. The delayed planting date and the drought from mid-Jun until harvest resulted in lower than average yields. Evaluation criteria consisted of weekly counts of all CPB life stages present on 10 randomly chosen stems/ plot, defoliation ratings on 11 and 23 Jun, and yield data.