Fungicide and Insecticide Interactions with In-Furrow Treatments, 1988

Abstract

Abstract Temik and Orthene were main plot treatments, applied in furrow at 0.5 lb (AI)/acre, Subplot treatments were the fungicides Dithane, Ridomil, and Terraclor Super X (TSX) as well as tank mixtures of Dithane + Ridomil and Ridomil + Terraclor. The granular formulation of TSX applied at 10 lb (form.)/acre was the fungicide standard. Test plots of 4 rows (40-inch spacing) by 65 ft were replicated 4 times in a randomized complete block design. Cotton was planted at a rate of 52,000 plants/acre 6 May on a Commerce silt loam soil at the Northeast Research Station, St. Joseph, La., and fertilized with 70 lb nitrogen/acre. Granular treatments were applied in furrow with a John Deere 7300 series planter equipped with split applicator boxes. Liquids were applied with a CO2 system calibrated to deliver 5 gal/acre. Major and secondary pest treatments were initiated in late June and maintained as needed through August. Treatment efficacy for thrips and aphids was measured by washing insects from 5 seedling cotton plants/plot onto 300-mesh screens, backwashing them onto lined filter paper (7 cm), and counting them with the aid of a binocular dissecting microscope. Collections and observations were made 18 May and 6 Jun. Data on insect populations are reported as the mean of these 2 dates. Stand data were recorded by counting all plants on the center 2 rows of each plot 23 May and 20 Jun. Plant population data reported are the means for these 2 dates. Leaf area data were recorded 6 Jun by randomly selecting 5 plants/plot and measuring all leaves with a LI-COR leaf area machine. Plant height data were recorded on 1 Jun. Ten plants/plot were randomly selected for the measurements. Yield was estimated by harvesting all 4 rows of each plot with a mechanical harvester on 9 Sep.