Irish Potato, Control of Colorado Potato Beetle, 1987

The experiments were randomized complete block designs with 6 replicates. Experiment CPB-A was planted 8 May, and experiments CPB-B and CPB-C were planted 11 May at Presque Isle, Maine, on land that was in clover in 1986. The 3.0-m space between blocks was bare soil and the 4-row plots were separated by 2 rows of untreated potatoes. All rows were planted with an assisted-feed planter 0.9 m apart and 15.0 m long, and the healthy seed pieces (75 g) were 30 cm apart. Fertilization and hilling practices were normal for the area. Late blight was controlled by 7 foliar applications of Dithane F-45 (2338 ml/ha the weeks of 6, 13, and 20 Jul; 2806 ml/ha the weeks of 27 Jul and 3, 10, and 17 Aug). Foliar insecticide applications were made with a Century boom sprayer, 3 nozzles/row at 7.0 kg/cm2 pressure and 1.2 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). Means of the sum of larvae and adult beetles were compared using DMRT and then reconverted. The soil was classified as Caribou Loam, pH 5.2. Total monthly rainfall for June, July, and August was 8.8, 7.6, and 4.4 cm, respectively. The average temperature for each of the same 3 months was 16.5, 19.0, and 19.1°C.