Recently, research has shown reduction in cotton injury from soil-applied clomazone when in-furrow application of phorate is used. Troublesome weeds such as prickly sida, spurges, velvetleaf, and certain annual grasses are susceptible to clomazone. Therefore, clomazone has the potential of becoming a component in herbicide programs for weed management in cotton.

Clomazone was applied preplant incorporated (PPI) and preemergence (PRE) at rates of 0.50 and 0.75 lb ai/acre in combination with fluometuron (1.5 lb/acre). Pendimethalin (PPI, 1.0 lb/acre), norflurazon (split application, 0.75 + 0.75 lb/acre), clomazone (PPI, 1.0 lb/acre), and pendimethalin + clomazone (PPI, 1. 0 + 0. 25 lb/acre) were also applied with fluometuron. The experiment was conducted on a Sharkey silty clay with 2.2% organic matter and pH of 6.9. In a separate experiment, clomazone was applied PRE at 0.75 and 1.0 lb/acre with trifluralin (PPI, 1.0 lb/acre) both with and without fluometuron (PRE, 0.84 lb/acre). Soil type was a Taloka silt loam with 1.3% organic matter and pH 6.7. Phorate was applied at 1.0 lb/acre as an in-furrow insecticide treatment in both experiments.

Cotton 'Deltapine 50' response to clomazone applied at 0.50, 0.75, and 1.0 lb/acre PRE was evaluated in presence of aldicarb, disulfoton, fenamiphos, or phorate applied at 1.0 lb ai/acre. Additional insecticide treatments included disulfoton + pentachloronitrobenzene (PCNB) and aldicarb + PCNB at 15 lb product/acre. Soil type was a Sharkey silty clay. A greenhouse experiment was conducted to determine the effect of soil type on cotton 'Deltapine 50' injury from clomazone. Soils evaluated were a Sharkey silty clay and a Taloka silt loam. A factorial arrangement of treatments included clomazone (0, 0.50, 0.75, and 1.0 lb/acre), phorate (D and 1.0 lb/acre), and the two soil types.

Clomazone applied at 0.50 or 0.75 lb/acre with fluometuron provided similar control of prickly sida, spotted spurge, velvetleaf, large crabgrass, smooth pigweed, hemp sesbania, and sicklepod. Entire leaf morningglory was greater with 0.50 lb/acre PRE than with the same rate applied PPI. There was no difference in control with 0.75 lb/acre regardless of application method. Control of prickly sida, velvetleaf, and sicklepod was greater with all herbicide combinations than with pendimethalin + fluometuron. On the Taloka silt loam, entireleaf morningglory control with trifluralin + fluometuron was greater than trifluralin + clomazone, regardless of clomazone rate. Addition of clomazone to trifluralin + fluometuron improved common cocklebur control (92% versus 67%).

Aldicarb, fenamiphos, and aldicarb + PCNB were not effective in protecting cotton from clomazone injury 3 weeks after planting (WAP). Averaged over these insecticides, approximately 23, 29, and 42% injury was noted at clomazone rates of 0.50, 0.75, and 1.0 lb/acre, respectively. Disulfoton, phorate, and disulfoton + PCNB reduced injury to less than 7% at all clomazone rates. However, only slight injury was present with all treatments 6 WAP and seedcotton yields were similar to the untreated check (no clomazone). Reduction in cotton fresh weight from clomazone in absence of phorate was greater on the Taloka silt loam (62%) than the Sharkey silty clay (13%). Phorate reduced injury similarly with both soils (<16%).