The influence of temperature and relative humidity on the activity of acifluorfen, fomesafen, lactofen, and acifluorfen plus bentazon on prickly sida, pitted and entireleaf morningglory, and common cocklebur was evaluated in a growth chamber. Reduced control of all species was observed at 50% relative humidity as compared to 85% relative humidity when temperatures were higher (32/55 C day/night). Similar response to relative humidity was observed at the lower temperature (25/15 C) when treatments were applied 14 days after emergence (DAE). Changes in temperature at the same relative humidity did not alter herbicidal activity. Delaying application timing from 7 to 14 DAE decreased control by all herbicides except lactofen applied at high relative humidity, which controlled prickly sida at both 7 and 14 DAE.

The weed control spectrum of clomazone, the influence of clomazone on the performance of other herbicides, and the performance of tank mixtures containing clomazone were evaluated from 1985 through 1987. Clomazone applied preemergence at 280 g ai/ha controlled 90 to 100% of barnyardgrass, giant foxtail, goosegrass, large crabgrass, seedling johnsongrass, prickly sida, and velvetleaf. Clomazone at reduced rates was more effective applied preemergence than preplant-incorporated for 10 of 23 weed species. Clomazone enhanced imazaquin activity on entireleaf morningglory and sicklepod in 1986. A tank mixture of clomazone, imazaquin, and metribuzin at half the labeled rates reduced soybean injury, increased soybean yield, and controlled weeds as well as the mixture at labeled rates.

In 1987 and 1988, effects of full-season interference of individual weeds on cotton yield were measured with area of influence procedures. In 1987, one spurred anoda, common cocklebur, large crabgrass, jimsonweed, common lambsquarters, redroot pigweed, common ragweed, or prickly sida plant per 3 m of row reduced cotton yield between 1% and 7%. Sicklepod did not cause a detectable yield loss. Redroot pigweed, common cocklebur and common ragweed caused 7%, 6% and 5% yield loss, respectively, in 1987. In row weed influence varied from 17 cm (large crabgrass interference) to 86 cm (common cocklebur interference). In 1988, yield losses by individual weeds ranged from 3% to 27%. Common cocklebur, jimsonweed, and common ragweed reduced cotton yields 28%, 15% and 12%, respectively. Spurred anoda and common cocklebur influenced 160 cm and 136 cm of cotton row, respectively. Sicklepod influenced only 47 cm of cotton row.

Clomazone was evaluated preplant incorporated (PPI) or post-transplant (PT) for weed control in sweet potatoes. No crop injury by clomazone was detected. Clomazone controlled (≥90%). broadleaf signalgrass, large crabgrass, barnyardgrass, and prickly sida at all rates and methods of application (MOA). Common cocklebur was controlled (≥93%) by clomazone at 1.1 kg ai ha-1 applied PT or at 3.4 kg ai ha-1 PPI in 1988 and at all rates and MOA in 1989. Clomazone did not control carpetweed.

Fumonisin B1 (FB1) sprayed on intact jimsonweed plants at 10 to 200 μg ml–1 caused chlorosis and necrosis on three- to four-leaf plants and reduced their height and biomass. Excised leaves of jimsonweed were necrotic on both surfaces after treatment with FB1 at 10 to 200 μg ml–1. The degree of damage increased with the concentration of FB1. The minimum amount of FB1 that damaged excised leaves was 0.05 μg. The symptoms of toxicity on sensitive plants varied with concentration of FB1. Symptoms observed included: chlorosis (creeping cucumber), necrosis (jimsonweed and common sunflower), black leaf lesions (sicklepod), curl of tissues (soybean), stunting, defoliation (hemp sesbania and northern jointvetch), and death (prickly sida, spurred anoda, northern jointvetch, and jimsonweed). Monocots (barley, bermudagrass, corn, johnsongrass, rice, sorghum, and wheat) were not visibly affected by FB1. This is the first evidence of the phytotoxic properties of fumonisin B1 against a wide variety of weeds and crop cultivars.

Field studies were conducted at five locations in North Carolina and Virginia during 1996 and 1997 to evaluate weed control, peanut (Arachis hypogaea) response, and peanut yield following diclosulam applied preplant incorporated (PPI) and in systems with commercial herbicide standards. All plots received a PPI treatment of ethalfluralin at 840 g ai/ha. Ethalfluralin plus diclosulam controlled entireleaf morningglory (Ipomoea hederacea var. integriuscula), ivyleaf morningglory (I. hederacea), pitted morningglory (I. lacunosa), common lambsquarters (Chenopodium album), eclipta (Eclipta prostrata), and prickly sida (Sida spinosa) as well as and frequently better than ethalfluralin PPI followed by (fb) acifluorfen plus bentazon postemergence (POST), paraquat plus bentazon early postemergence (EPOST) fb imazapic POST, or imazapic POST. Systems with ethalfluralin plus diclosulam PPI at 26 g ai/ha fb acifluorfen plus bentazon POST controlled a broader spectrum of weeds and yielded greater than systems of ethalfluralin PPI fb imazapic POST or ethalfluralin PPI fb acifluorfen plus bentazon POST. Peanut exhibited excellent tolerance to diclosulam PPI at 17, 26, or 35 g/ha.

Tolerance of species to foliar applications of the ethyl ester of chlorimuron as determined in greenhouse studies with 21-day-old seedlings was: soybean = peanut > prickly sida > sicklepod > Florida beggarweed > common cocklebur. Absorption of foliar-applied 14C-chlorimuron 72 h after application was similar in soybean, peanut, sicklepod, common cocklebur, and prickly sida, but much less in Florida beggarweed. Slight symplasmic and apoplasmic translocation of the herbicide was evident in all species. Metabolism of chlorimuron 72 h after application was greatest in soybean and least in common cocklebur. Species tolerance to chlorimuron was directly correlated (r2 = 0.93) to the amount of unmetabolized chlorimuron (dpm/g dry wt) in the plant. Peanut exhibited increased tolerance to chlorimuron with age; this result was attributed to reduced absorption and translocation and more extensive metabolism of the absorbed herbicide by older plants.

Field experiment were conducted to determine interactions of chlorimuron or imazaquin with fomesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with fomesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when low rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with fomesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai ha–1 imazaquin was combined with 210 g ai ha–1 fomesafen or 110 or 220 g ai ha–1 lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai ha–1 chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g ha–1 imazaquin was combined with 110 g ha–1 lactofen or 210 g ai ha–1 acifluorfen; however, at higher rates of chlorimuron or imazaquin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.

Field experiments were conducted in 1988 and 1989 to evaluate timing of POST herbicide application in peanut for annual broadleaf weed control, peanut yield, and net returns. Bentazon tank-mixtures with either acifluorfen or paraquat controlled common lambsquarters, prickly sida, and morningglory species equally when applied either at ground-cracking (GC) or 2 wk after ground-cracking (2WGC). Paraquat controlled common lambsquarters least (32 to 33%). Bentazon plus acifluorfen plus BCH 81508S controlled 82% common lambsquarters at 2WGC compared with 66% control from bentazon plus acifluorfen plus a crop oil concentrate. Lactofen controlled 86% common lambsquarters when applied at GC compared to 34% at 2WGC. All applications applied at 4 wk after GC (4WGC) controlled essentially no annual broadleaf weeds. Higher yields and net returns were generally obtained with earlier herbicide applications. Bentazon tank-mixtures with acifluorfen provided equivalent peanut yields and net returns for GC and 2WGC applications.

Field studies in 1990 and 1991 at six locations in Georgia and one location in North Carolina evaluated AC 263,222 for weed control, peanut tolerance, and yield. AC 263,222 applied early postemergence at 71 g ai ha−1 controlled bristly starbur, coffee senna, common lambsquarters, Ipomoea species, prickly sida, sicklepod, smallflower morningglory, and yellow nutsedge at least 91%. AC 263,222 controlled common cocklebur 77% and Florida beggarweed from 47 to 100%. Crop injury was 4% for AC 263,222 applied once and 12% or less from two applications. Mixtures of bentazon with AC 263,222 did not improve control compared to AC 263,222 alone. Imazethapyr did not improve control of AC 263,222 systems. In several locations, bentazon reduced control of Florida beggarweed with AC 263,222 when applied in a mixture compared to AC 263,222 alone. Weed control from the standard of paraquat plus bentazon applied early postemergence followed by paraquat, bentazon plus 2,4-DB applied POST did not provide the level or spectrum of weed control as AC 263,222 systems.

Field trials were conducted in 1986 and 1987 to determine the effects of moisture on herbicidal activity of cinmethylin applied preemergence at 0.0, 0.3, 0.6, and 0.9 kg ai ha to both dry and moist sandy loam soil. Herbicide application was followed by varying amounts of irrigation. Weed species included velvetleaf, prickly sida, green foxtail, and barnyardgrass. When cinmethylin was applied to a moist soil or when 2.5 cm of irrigation was applied 5 days after cinmethylin application to a dry soil, overall weed control was reduced. Optimum weed control resulted from cinmethylin application to dry soil followed either by a 2.5-cm irrigation within 8 h or a 7.6-cm irrigation within 36 h.

Field trials were conducted from 1991 to 1993 in the northern cotton-producing area of Alabama to evaluate the interaction of various production inputs for pest management and cotton development, maturity, and yield. Two levels of tillage (conventional and no-till), herbicide (1.12 and 2.24 kg ai ha−1 fluometuron, preemergence, with post-directed herbicides), insecticide (0.5 and 0.85 kg ai ha−1 aldicarb, in-furrow), and fungicide (0.9 kg ai ha−1 quintozene plus ethridazole, in-furrow or 0.14 kg ai ha−1 metalaxyl, hopper-box) programs were evaluated. The inputs investigated did not interact significantly to change the overall production strategy. Prickly sida required a higher level of herbicide input than did the entireleaf/ivyleaf morningglory complex. Both species were sufficiently controlled using reduced levels of fluometuron without sacrificing yield; however, cultivation was necessary in conventional tillage treatments to maintain control. A postemergence-directed herbicide treatment was also necessary for weed control, regardless of tillage. Decreasing the levels of each input simultaneously did not interact to affect cotton stand, height, early-season thrips counts, cotton maturity, or yield. Cotton was shorter in no-till than conventional plots.

Data from field studies at Fayetteville, AR, were used to predict the herbicide rate needed to provide 70, 80, or 90% control of a weed based upon weed age. Reduced herbicide rates generally needed to be applied within 6 to 12 d after emergence to control weeds 90%. Reduced rates (280 g ai ha–1 or less) of acifluorfen controlled hemp sesbania, smooth pigweed, Palmer amaranth, and pitted and entireleaf morningglory 90%. Bentazon at 350 to 650 g ai ha–1 controlled common cocklebur and prickly sida 90%. Common cocklebur, smooth pigweed, and pitted morningglory were controlled 90% with chlorimuron at 2 to 5 g ai ha–1 and imazaquin at 20 to 80 g ai ha–1. Prickly sida and hemp sesbania were controlled 90% with imazaquin at 70 g ha–1 and chlorimuron at 6 g ha–1, respectively. Barnyardgrass, large crabgrass, red rice, and sicklepod were not controlled with reduced herbicide rates.