Field experiments were conducted in 1994 and 1995 to determine if the sodium salt of pyrithiobac or bromoxynil applied in a low-volume, air-assist spray system controlled entireleaf morningglory, pitted morningglory, and smallflower morningglory as well as treatments applied with a conventional hydraulic fan spraying system, and to determine if herbicide rates could be reduced when using the low-volume spraying system. Pyrithiobac at 0.035 and 0.071 kg ai/ha and bromoxynil at 0.56 and 1.12 kg ai/ha were applied alone and in combination with DSMA at 1.7 kg ai/ha or MSMA at 1.7 kg ai/ha. Spraying systems were calibrated to deliver 26 L/ha and 140 L/ha for the low-volume and conventional systems, respectively. No significant differences in control were noted between low-volume and conventional spray systems when herbicides were applied at the suggested use rates of 0.071 and 1.12 kg ai/ha for pyrithiobac and bromoxynil, respectively. Morningglory control was reduced when pyrithiobac and bromoxynil were applied at one-half the suggested use rate regardless of the spraying systems. Bromoxynil alone generally controlled pitted and entireleaf morningglory better than pyrithiobac alone regardless of rate and application method. However, pyrithiobac generally provided better control of smallflower morningglory than bromoxynil. Adding MSMA or DSMA to bromoxynil and pyrithiobac increased control of both weed species.

Greenhouse and field studies were conducted to determine the interaction of clethodim sprayed in low volume with pyrithiobac or bromoxynil and to determine the influence of these mixtures on large crabgrass control. A low-volume, air-assisted spraying system was calibrated to deliver 26 L/ha and was compared to a conventional hydraulic fan spraying system calibrated to deliver 140 L/ha. Greenhouse data indicated that carrier volume had no effect on large crabgrass control with clethodim. The addition of pyrithiobac to clethodim in mixture was antagonistic compared to control with clethodim applied alone. The addition of bromoxynil to clethodim in mixture was synergistic. Field studies showed similar results.

Field studies were conducted in Alabama in 2016 and 2017 to determine the effect of postemergence applications of glufosinate alone and glufosinate applied with S-metolachlor, using two different nozzle types, on LibertyLink®, XtendFlex®, and WideStrike® cotton growth and yield. Two applications of glufosinate at 0.6 kg ha−1, and glufosinate with S-metolachlor at 1.39 kg ha−1 were applied to each cotton cultivar at the four-leaf and eight-leaf growth stages using a flatfan and Turbo TeeJet Induction® nozzle. Visual estimates of cotton injury were evaluated after each application, as well as yield. No differences in yield, within each cotton cultivar were observed for either year. Visual injury was higher for WideStrike cotton than LibertyLink or XtendFlex cultivars. On average, glufosinate applied with S-metolachlor resulted in higher injury than glufosinate applied alone. In LibertyLink cotton, applications made with TTI nozzles resulted in greater injury than flatfan nozzles. However, cotton injury was transient and did not affect cotton yields. These data indicate that applications of glufosinate and glufosinate applied with S-metolachlor, at 0.6 kg ha−1 and 1.39 kg ha−1, respectively, with either a flatfan or TTI nozzle, can have no detrimental effect on cotton growth or yield.

Aims: Field studies were conducted to determine sesame response to the pre-emergence herbicides (acetochlor at 1.7 kg ai ha-1; S-metolachlor at 0.72, 1.43, and 2.86 kg ai ha-1; dimethenamid-P at 0.84 kg ai ha-1; pethoxamid at 0.22 kg ai ha-1; pyroxasulfone at 0.09 kg ai ha-1and bicyclopyrone at 0.12 and 0.24 kg ai ha-1) applied 3 or 6 days after 50% emergence. Study Design:  Randomized complete block design with 3-4 reps depending on location. Place and Duration of Study: Sesame growing areas of Alabama, Mississippi, and Texas during the 2016 through 2018 growing seasons. Methodology: Treatments consisted of a factorial arrangement of herbicide treatments at two early POST application timings. A non-treated control was included for comparison. Crop oil concentrate (Agridex®, Helena, Collierville, TN 38017) at 1.0% v/v was added to all herbicide treatments. Plot size was either five rows (76 cm apart) by 9.1 m or four rows (101 cm apart) by 7.3 m depending on location. Only the two middle rows were sprayed and the other rows were untreated and served as buffers. Sesame cultivars were seeded approximately 1.0 to 2.0 cm deep at 9 kg/ha at all locations. Injury was evaluated early-season, 7 to 27 days after herbicide application (DAA), and later, 28 to 147 DAA, based on a scale of 0 (no sesame injury) to 100 (complete sesame death). Injury consisted of stuntingand leaf chlorosis and/or necrosis. Results: All herbicides tested resulted in significant injury to sesame at some location and application timing. None of the herbicides evaluated are safe to use early POST on sesame without causing significant injury.  Conclusion: The ability of sesame to recover from significant injury and compensate for injury led to no yield loss in many instances. However, levels of injury observed are not acceptable by growers and will not allow the use of these herbicides soon after sesame emergence.