Foliar Sprays for Colorado Potato Beetle Control, 1981

‘Norchip’ Irish potatoes were planted with 10 inch spacing in 36 inch rows on Mar 4. Each plot consisted of a single, 25 ft long row bordered on each side by an untreated row. The treatments were replicated 4 times in a randomized block design. The sprays were applied with a D. B. Smith 5 gal knapsack, hand-operated, compressed-air sprayer calibrated to deliver 75 gal/acre (40 psi) using a D. B. Smith #E-147 adjustable cone nozzle. Applications were made on May 29, Jun 8, 15, 22 and 29. Yields were taken on Jul 1. Evaluation criteria consisted of direct counts of the number of Colorado potato beetle larvae/10 hills and late season foliage injury ratings. Foliage injury ratings were on a scale of 0-5 as follows: 0) no damage; 1) slight feeding, less than 5% defoliation; 2) visible feeding with 5-10% defoliation; 3) moderate damage, 10-25% defoliation; 4) heavy damage, 25-50% defoliation; 5) severe damage, greater than 50% defoliation.