ABSTRACT

Field experiments were conducted in 1989 and 1990 on a silt loam soil at Fayetteville, AR, to determine the effect of spray volume and adjuvants on entire leaf morningglory (Ipomoea hederacea var. integriuscula Gray) control with DPX-PE350 applied postemergence. DPX-PE350 at 0.022, 0.1, and 0.15 lb ai A^-1 was applied with no adjuvant, crop oil concentrate (1.0% v/v), or a nonionic surfactant (0.25%) in spray volumes of 10, 25, and 40 gpa. An experiment also was conducted to evaluate broadleaf weed control with DPX-PE350 at 0.1 lb A^-1 applied alone or in combination with fluometuron and MSMA, each applied at 0.45 and 0.9 lb ai A^-1. Fluometuron and MSMA also were applied alone. All treatments contained a nonionic surfactant at 0.25%. A greenhouse experiment was conducted to determine the effect of site of application and soil series on entireleaf morningglory control with 0.01, 0.022, and 0.05 lb A^-1 of DPX-PE350. DPX-PE350 was applied to the soil only, foliage only, or the soil plus foliage. Soils were a Sharkey silty clay with 3.3% organic matter and pH 5.9 and a Calloway silt loam with 1.1% organic matter and pH 6.5. The experimental design in all experiments was a randomized complete block with three or four replications.

Spray volume had no effect on entireleaf morningglory control. Control with DPX-PE350 was greater with a crop oil concentrate or nonionic surfactant than with no adjuvant. Crop oil concentrate was the most efficacious of the adjuvants. Control of entireleaf morningglory, hemp sesbania [Sesbania exaltata (Raf.)Rybd. ex A.W. Hill], and velvetleaf (Abutilon thiophrasti L.) with DPX-PE350 was not affected by fluometuron or MSMA. When DPX-PE350 was mixed with MSMA, the combination provided greater sicklepod control than either herbicide applied alone. Entireleaf morningglory control with DPX-PE350 applied to the soil only following emergence was less than that of foliar plus soil application. DPX-PE350 applied to the foliage only was as effective as the soil plus foliage treatment. Control on the Sharkey silty clay was less than control on the Calloway silt loam when DPX-PE350 was applied to the soil only.