Control of Certain Potato Insects in Arizona with Soil Applications of Granulated Phorate

The principal insect pests of potatoes in Arizona requiring Control are the potato psyllids, green peach aphids, leafhoppers and thrips. Of these the most serious pest is the potato psyllid, Paratrioza cockerelli (Sulc). A soil application of granules containing 10% phorate at the rate of 20 pounds per acre (2-pounds actual) made to Red Pontiac, and Kennebec potatoes at time of planting gave good control of the potato psyllid and green peach aphid ( Myzus persicae (Sulzer)), Granules were applied approximately 2 inches below the seed piece and 4 to 5 inches to the side in the fertilizer band on one side only. The young plants did not readily pick up the phorate from the soil until after the first irrigation. Effective insect control was obtained for approximately 100 days after planting. A fertilizer-phorate mixture (0.2% phorate) applied to both sides of the seed piece also gave satisfactory control of psyllids and aphids. An aphid buildup may occur late ill the growing season as the effectiveness of the phorate diminishes. Luck of psyllid control was found to reduce the potato yield by 50% or more.