Field studies were undertaken in 1992 and 1993 to investigate the control of wild oat and green foxtail in flax with reduced rates of fluazifop-P and clethodim applied as tank-mixtures. Fluazifop-P plus clethodim at 50 + 18 g ai/ha controlled wild oat and green foxtail and was as effective as full rates of either herbicide applied alone. These rates represent a 20% reduction in total amount of active ingredient required to control wild oat and green foxtail. Application of fluazifop-P, and/or clethodim prior to the 3- to 4-leaf stage failed to control late emerging grass weeds. Application of graminicide mixtures at or after the 3- to 4-leaf stage controlled late emerging grass weeds and did not affect flax yield. When applied late, fluazifop-P at 175 g/ha tended to reduce flax yield, although weed control was acceptable and no foliar injury was observed following treatment. The efficacy of graminicide mixtures was reduced by addition of bromoxynil plus MCPA to the spray mix.

Field trials were conducted in Georgia and South Carolina in 2000 and 2001 to evaluate the effects of glyphosate, diflubenzuron, and boron combinations on crop injury and soybean yield. No interactions among glyphosate, diflubenzuron, and boron were observed. Both glyphosate and boron caused significant foliar injury (chlorosis and leaf burn) ranging from 7 to 10% in one of three locations. Diflubenzuron did not cause significant soybean injury at any location. Soybean injury symptoms observed in these experiments were transient and did not negatively affect yield.

Field studies were conducted in 1995 and 1996 at three locations in North Carolina to evaluate weed control and soybean injury with postemergence (POST) treatments of cloransulam-methyl alone or in tank-mixture with acifluorfen, fomesafen, or lactofen compared with a commercial standard of acifluorfen plus bentazon. Soybean injury was 2 to 3% 7 d after treatment with cloransulam-methyl applied alone and 11 to 46% when applied with fomesafen, lactofen, acifluorfen, or acifluorfen plus bentazon. Cloransulam-methyl applied alone controlled 95% of entireleaf morningglory and ivyleaf morningglory. Control was not increased by the addition of acifluorfen, fomesafen, or lactofen. Cloransulam-methyl improved the control of common lambsquarters to at least 81% compared with dimethenamid applied preemergence alone (69% control). All diphenyl ether herbicide treatments controlled common lambsquarters at least 91%. Prickly sida control by cloransulam-methyl ranged from 14 to 73% 8 wk after treatment. Control of prickly sida was varied by diphenyl ether herbicides (73 to 100% control). Tank-mixtures of cloransulam-methyl + fomesafen and cloransulam-methyl + acifluorfen increased the control of prickly sida over either herbicide applied alone. Soybean yield was greater for all tank-mixtures than for any diphenyl ether herbicide or for cloransulam-methyl treatment applied alone. But only the acifluorfen + cloransulam-methyl treatment had higher economic returns than the cloransulam-methyl treatment alone. All other POST systems, with the exception of lactofen applied alone, had similar economic returns. Tank-mixtures of cloransulam-methyl and diphenyl ether herbicides increased the spectrum of control and soybean yield compared with these herbicides applied alone.

A 2-yr study was conducted to evaluate bell pepper response and honeyvine milkweed control from PRE herbicides, clomazone and trifluralin, applied under polyethylene mulch. Clomazone (0.8 and 1.4 kg ai ha−1) and trifluralin (0.7 and 1.1 kg ai ha−1) were applied alone or in combination. Herbicides were applied after beds were made and before polyethylene mulch was laid, followed by transplanting pepper within hours of herbicide application. In both years, initial bleaching of lower leaves was observed; the injury was observed in some treatments, but not others. Honeyvine milkweed, growing in the planting hole, exhibited significant bleaching and stunting in most herbicide treatments. Both clomazone and trifluralin resulted in season-long honeyvine milkweed control in both years. However, the use of clomazone and trifluralin together for control of honeyvine milkweed does not seem justified due to the potential for herbicide antagonism, as indicated in this study. The total number and fresh weight of harvested bell pepper were not affected by the herbicides or rates. All herbicide treatments resulted in about twice the yield (average of 8.8 kg) of the hand-weeded control (4.6 kg) in both years. This study strongly supports the safety and effectiveness of clomazone and/or trifluralin applied pretransplant under polyethylene mulch in bell pepper production for control of honeyvine milkweed.