Control of Potato Infesting Aphids, 1989

Abstract

Abstract The foliar and systemic experiments were randomized complete block designs with 6 replicates each and were conducted at Presque Isle, ME. The planting dates were 23 May for the foliar application experiment and 24 May for the systemic application experiment. The 3 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 on 27 Jun. Each plot consisted of 4 rows of potatoes, each row 0.9 m apart and 15.0 m long. The healthy Katahdin seed pieces ca. 75 g each were planted with a tractor-pulled, assisted-feed planter. Fertilizer and hilling practices were normal for the area. Sidedress applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide. 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 aphids (by species) were counted on top, middle, and bottom leaves of 25 plants in the middle rows of each plot. When dates of count and application were the same, aphid counts were made prior to applications of the insecticide. Analyses of variance were calculated following transformation of the data using log10 (x + 1). Means of the total number of wingless aphids were compared using DMRT and then reconverted, Total monthly rainfall for Jun, Jul and Aug was respectively 6.0, 7.7 and 11.5 cm. The average temperature for each of the same 3 months was 16.5, 18.6 and 18.2°C.