Irish Potato, Control of Potato Infesting Aphids, 1990

Abstract

Abstract Aphid-A and Aphid-B experiments were randomized complete block designs with four and six replicates respectively and were conducted at Presque Isle, ME on land that was in clover in 1989. The planting dates were 17 May and 29 May. The 3.0 m space between blocks and the 1.8 m space between the four-row polts were sown to oats on 29 Jun in the Aphid-B experiment and were left fallow in the Aphid-A experiment. 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. Fertilizer 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). Sidedress and furrow 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, three nozzles per 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 on untransformed data in the Aphid-A experiment and following transformation of the data using log10(x + 1) for the Aphid-B experiment. Means of the total number of wingless aphids 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, 14.8 cm. The average temperature for each of the same 3 mo was 17.6, 19.5 and 19.7 deg C.