Reduction of Nematode and Insect Damage to Potatoes by Band Application of Systemic Insecticides and Soil Fumigation

Abstract

Four systemic insecticides and a fumigant were applied for control of nematodes and insects in potatoes. The insecticides carbofuran, aldicarb, Dasanit® ( 0,0 - diethyl O -[ p -(methylsulfinyl) phenyl] phosphorothioate), and disulfoton were applied in a band at planting time to 1 side of the row at the rate of 44.8 kg per hectare. This method of treatment was compared with preplanting fumigation with Telone® (mixed dichloropropenes) at the rate of 233.7 liters/hectare. Aldicarb and Telone reduced populations of meadow nematodes, Pratylenchus penetrans Cobb, 90% or more in soil to a depth of 30.5 cm. To a depth of 20.3 cm carbofuran gave 90% reduction in populations. Dasanit gave 80% reduction, and disulfoton reduced populations only 60%. Carbofuran gave protection to the untreated side of the row. Aldicarb, disulfoton, and Dasanit appeared to repel tobacco stunt nematodes, Tylenchorhynchus claytoni Steiner. At harvest time populations of meadow and tobacco stunt nematodes were 90% lower in Aldicarb plots and 60-80% lower in Telone and carbofuran plots than in untreated plots. Weekly applications of 1.12 kg per hectare of either endosulfan or carbaryl, used alternately, were made to all plots, including controls. When green peach aphids, Myzus persicae (Sulzer), became a problem, malathion was substituted for carbaryl. Aldicarb, Dasanit, and carbofuran reduced feeding by potato flea beetles. Epitrix cucumeris (Harris) 95% or more. Aldicarb and carbofuran decreased Colorado potato beetle, Leptinotarsa decemlineata (Say), damage more than 80%. All systemic insecticides reduced aphid damage in July, but in August Dasanit was less effective than the others. Aphid injury in early August was less severe on plants grown in Telone-treated soil than in untreated soil. Disease levels were low in all plots.