Irish Potato, Control of Potato Infesting Aphids, 1979

Experiments A, B, and C were randomized complete block designs with 6 replicates each and were conducted at Presque Isle, ME on land that was sown to oats In 1978. The planting date was May 21 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 after planting. Each plot consisted of 4 rows of potatoes 0.9 m apart and 15.0 m long. The healthy seed pieces ca 57g each 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 weeks of Jul 1 through 22, 1781 g/ha weeks of Jul 29 through Aug 12, and 2242 g/ha weeks of Aug 19 and 26). Soil applications of insecticide 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/row at 7.0 kg/cm2 pressure 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 dates 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 June, July and August was respectively 72.7, 49.9 and 138.5 percent of normal. Temperature for the same 3 months departed +5.0°, +7.2° and +3.9°C from normal.