Foliar Sprays to Control Insect Pests on Late-Planted Sweet Corn, 1984

Sweet corn was planted 13 Jul to a Sassafras sandy loam field. Plots were 4 rows wide on 30-inch centers and 25 ft long. Whorl sprays were applied with a tractor-mounted boom sprayer with 1 nozzle over the row calibrated to deliver 55 gal/acre at 200 psi; foliar sprays at silking were applied with a self-propelled, high-clearance sprayer with 4 nozzles/row, directed at the ear zone, which delivered 83 gal/A at 200 psi operated at 2 mph. The center 2 rows of each were treated and the outer 2 rows were untreated guard rows. Whorl treatments were applied on 10 and 22 Aug. Foliar sprays at silking were applied on 12, 14, 17, 20 and 24 Sep. Twenty plants from the middle 2 rows were evaluated on 27 Aug for fall armyworm (FAW) and European corn borer (ECB) numbers and damage. The categories for armyworm foliar feeding damage are as follows: (0) no damage; (1) slight damage; (2) 10% damage; (3) moderate damage, up to 25% of the whorl destroyed; (4) heavy damage, up to 50% of the whorl destroyed and (5) severe damage, whorls destroyed. At harvest (27 Sep) 20 ears from the 2 center rows of each plot were evaluated for ‘worm’ damage as “none” (clean-no damage), “tip” (less than 1.5 inches tip damage) and “side” (culls). On 5 Nov, 20 stalks from the middle 2 rows of each plot were split from tassel to soil surface and each 2.5 cm of ECB damage was recorded as one cavity.