Foliar Sprays for Colorado Potato Beetle Control, 1982

‘Norchip’ Irish potatoes were planted with 10-inch plant spacing in 36-inch rows on Apr 8. 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 propane compressed air backpack sprayer using 3 hollow cone nozzles/row and delivering 75 gal water/acre at 40 psi. Applications were made on May 26, Jun 2, 9, 16 and 23. Yields were taken on Jul 20. 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.