Control of Rice Water Weevil with Nematodes, 1990

Abstract

Abstract Experiments, designed as randomized complete blocks, were conducted at the Texas A&M University Agricultural Research and Extension Center at Beaumont and its satellite station at Eagle Lake. Each of 2 experiments at Beaumont and a single experiment at Eagle Lake consisted of 5 and 8 treatments, respectively, all with 4 replications. Soil at Beaumont was Beaumont clay and that at Eagle Lake was Nada fine sandy loam. At the Beaumont location plots were 13 × 6 ft, broadcast sown to dry soil with 100 lbs seed/acre, and fertilized with urea at 110 lbs N/acre. Plots were flush irrigated (flooded for 24 to 48 h then drained) as needed until the permanent flood was applied on 4 Jun (22 d after seedling emergence through soil). On 30 May plots were treated with 3, 2, and 0.25 lbs (AI)/acre propanil, thiobencarb, and bentazon, respectively. Metal barriers were placed around plots to receive treatments applied to flood water. Treatments were applied as described in the tables. Nematode treatments were applied with a 4 nozzle hand-held boom sprayer using CO2, at 22 psi, as a propellant. Nozzles were LF 3, 80 degrees without screens. Final spray vol was 100 gal/acre. Nematode treatments were made at dusk with the spray boom positioned below the canopy to prevent drift. Furadan was applied with a hand-held shaker. At panicle differentiation (29 Jun) plots were fertilized with urea at 60 lbs N/acre. From 25 to 27 Jun, 5, 4-inch diameter × 4-inch deep soil cores were removed from each plot of Experiment 1. Each core contained a single plant with roots which were washed and inspected for immature RWW. Plots in Experiment 2 were sampled 9-10 Jul as in Experiment 1. At maturity plots in both experiments were harvested, yields adjusted to 12% moisture, and grain milled to determine quality. Plots at Eagle Lake were 13 × 6 ft, drill planted (6-inch row spacing) at 100 lbs seed/acre, and fertilized with urea and 16-20-0 at 45 lbs N/acre on 21 Mar. Seedlings emerged through soil between 5 and 7 Apr. Plots were flush irrigated as needed until the permanent flood was applied 11 May (34 to 36 d after seedling emergence). On 19 Apr molinate, propanil, and bentazon were applied at 3.0; 3.0; and 0.5 lb (AI)/acre, respectively, followed by an application of thiobencarb, molinate, and propanil at 2.0; 3.0, and 3.0 lbs (AI)/acre, respectively, on 3 May. Treatments as listed in the table were applied as described for the experiments at Beaumont. At panicle differentiation (1 Jun), plots were fertilized with urea at 45 lbs N/acre. On 7 Jun (13 d after application of treatments), plots were sampled, as in experiments at Beaumont, for RWW immatures. Plots were not harvested; thus, yield and milling quality are not available for the Eagle Lake experiment. Data for RWW densities were transformed using Vx + 0.5; yield and milling data were not transformed. Data were subjected to ANOVA and where appropriate DMRT.