ABSTRACT

Field experiments were conducted on a Taloka silt loam at Fayetteville, AR, to determine the effect of DPX-PE350 and bromoxynil an annual grass control with sethoxydim, fluazifop-P, clethodim, and quizalofop. Large crabgrass (Digitaria sanguinalis L.), broadleaf signalgrass (Brachiaria platyphylla L.), seedling johnsongrass (sorghum halepense L.), shattercane (Sorghum vulgare), barnyardgrass (Echinochloa crusgalli L.), and entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray) were established in rows, and herbicides were applied on a 5-ft. swath perpendicular to the plant rows. In one experiment, DPX-PE350 at 0.10 lb ai A^-1 was applied alone and with sethoxydim and fluazifop-P, each at 0.09, 0.18, and 027 lb ai A^-1, clethodim at 0.035, 0.07, and 0.11 lb ai A^-1, and quizalofop at 0.018, 0.036, and 0.054 lb ai A-' to weeds in the 3- to 5-leaf stage of growth. Cotton had two leaves at time of application. In a separate experiment at four locations, rhizome johnsongrass control with DPX-PE350 and graminicides was evaluated. DPX-PE350 at 0.1 lb A^-1 was applied alone and with sethoxydim, fluazifop-P, clethodim, and quizalofop at 0.18, 0.18, 0.125, and 0.036 lb A^-1, respectively. In both experiments the graminicides also were applied alone. In a third experiment, large crabgrass control with tank-mix and sequential applications of sethoxydim at 0.2 lb A^-1 and DPX-PE350 (0.1 and 0.15 lb A^-1) was evaluated over a three-year period. DPX-PE350 was applied 3 days before, 3 days following, or in a tank mixture with sethoxydim. Sethoxydim also was applied alone. Large crabgrass was in the 3- to 4-leaf stage and the sethoxydim component was applied on the same day. All treatments contained crop oil concentrate at 1.0% v/v in 20 gpa and were applied at 22 psi. Soil moisture at time of application was adequate for normal plant growth. Visual estimates of percent control were recorded 3 weeks after treatment.

DPX-PE350 applied alone provided less than 20% control of large crabgrass and broadleaf signalgrass, approximately 55% control of green foxtail, and at least 87% control of shattercane and seedling johnsongrass. DPX-PE350 decreased large crabgrass control with all graminicides applied at the low rate. Efficacy of fluazifop-P was impaired the most. Broadleaf signalgrass and barnyardgrass control with sethoxydim and clethodim was not reduced by DPX-PE350. However, control with fluazifop-P and quizalofop was reduced, with fluazifop-P being affected the most. Increasing the graminicide rate reduced the antagonism. No antagonism between the graminicides and DPX-PE350 was observed on green foxtail, shattercane, or seedling johnsongrass control. Quizalofop was affected most. Graminicides had no effect on entireleaf morningglory with DPX-PE350. DPX-PE350 provided 56% control of rhizome johnsongrass. Control with quizalofop, fluazifop-P, and clethodim was not reduced by DPX- PE350; control with sethoxydim decreased by 12% when DPX-PE350 was added. Applying DPX-PE350 and sethoxydim sequentially eliminated antagonism occurring when the herbicides were applied in a tank mixture.