Irish Potato, Control of Colorado Potato Beetle, 1990

Abstract

Abstract The experiments were randomized complete block designs with 6 replicates, except experiment CPB-A which had 4 replicates. Experiment CPB-A was planted 17 May; experiments CPB-B, CPB-C, and CPB-D were planted 29 May; and experiment CPB-E was planted 31 May at Presque Isle, Maine, on land that was in clover in 1989. The 3.0 m space between blocks and the 1.8 m space between the four-row plots was bare soil. All rows were planted with an assisted-feed planter 0.9 m apart and 15.0 m long and the healthy whole Katahdin seed (ca 75 g) were 30 cm apart. Fertilization and cultivation practices were normal for the area. Late blight was controlled by 5 foliar applications of Manex 4 L (2338 ml/ha on 27 Jul; 2806 ml/ha on 3, 9, 16, and 23 Aug). Foliar insecticide applications were made with a Century boom sprayer, 3 nozzles/row at 6.3 kg/cm2 pressure and 0.94 kl/ha. Numbers of larvae and adults were counted on 25 whole plants in the middle rows of each plot. When dates of count and application were the same, beetle counts were made prior to application of insecticides. Analyses of variance were calculated following transformations of data using log10(x + 1), except experiment CPB-A where no transformations were done. Means of all larval stages and adult beetles were compared using DMRT. The soil was classified as Caribou Loam, pH 5.2. Total monthly rainfall for Jun, Jul, and Aug was respectively 7.3, 10.2, and 14.8 cm. The average temperature for each of the same 3 mo was 17.6, 19.5 and 19.7 deg C.