Irish Potato, Control of Potato Infesting Aphids, 1978

Experiments A and B were randomized complete block designs with 6 replicates and were conducted at Presque Isle, Maine on land that was sown to oats in 1977. The planting date was May 23‘78 for all experiments. In each experiment the 2.0 m space between blocks and the 1.4 m space between columns and at the sides and ends of the experiments were sown to oats two weeks after planting. Each plot consisted of 4 rows of potatoes 0.9 m apart and 15.0 m long. The 57 g healthy seed pieces were hand planted 30.0 cm apart. Fertilization and hilling practices were normal for the area. Late blight control was effected by weekly foliar applications of Rohm & Haas M45 (1121 g/ha week of Jul 7, 1781 g/ha weeks of Jul 10 through 24, and 2242 g/ha weeks of Jul 31 through Aug 28). Soil applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide into the furrow just prior to planting. Foliar insecticide applications were made with a Century boom sprayer, 3 nozzles per row at 7.0 kg/cm2 and 1.2 kl/ha. Foliar insecticides were mixed with the fungicide. Numbers of aphids (by species) were counted on top, middle, and bottom leaves of 25 plants in the 2 middle rows of each plot. When date of count and application are the same, aphid counts were made prior to application of the insecticide. Analyses of variance were calculated following transformation of the raw data using log10(x + 1). Means of the total number of wingless aphids were compared using Duncan’s new multiple range test and then reconverted as given in the Table. The soil was classified as Caribou Loam, pH 5.2. Rainfall for Jun, Jul, and Aug was respectively 103.7, 124.2, and 57.6 percent of normal. Temperature for the same 3 months departed + 0.6°, + 4.4°, and + 5.0°C from normal.