Coapplication of herbicides and insecticides affords growers an opportunity to control multiple pests with one application, given that efficacy is not compromised. Glufosinate was applied at 470 g ai/ha both alone and in combination with the insecticides acephate, acetamiprid, bifenthrin, cyfluthrin, dicrotophos, emamectin benzoate, imidacloprid, indoxacarb, lambda-cyhalothrin, methoxyfenozide, spinosad, or thiamethoxam to determine coapplication effects on control of some of the more common and/or troublesome broadleaf weeds infesting cotton. Hemp sesbania, pitted morningglory, prickly sida, redroot pigweed, and sicklepod were treated at the three- to four- or the seven- to eight-leaf growth stage. When applied at the earlier application timing, glufosinate applied alone provided complete control at 14 d after treatment, and control was unaffected by coapplication with insecticides. When glufosinate application was delayed to the later application timing, visual weed control was unaffected by insecticide coapplication. Fresh-weight reduction from the herbicide applied to larger weeds was negatively impacted by addition of the insecticides dicrotophos and imidacloprid with respect to redroot pigweed and prickly sida, but only in one of two experiments. In most cases, delaying application of glufosinate to larger weeds resulted in reduced control compared to that from a three- to four-leaf application, with the extent of reduction varying by species. Results indicate that when applied according to the herbicide label (three- to four-leaf stage), glufosinate/ insecticide coapplications offer producers the ability to integrate pest management strategies and to limit application costs without sacrificing control of the broadleaf weeds evaluated.

Diclosulam is registered for residual and postemergence control of several broadleaf weeds and suppression of annual sedges in peanut in the southeastern United States. Many producers apply herbicides and other pesticides simultaneously to increase the spectrum of pest control or to increase efficiency of operations. However, compatibility of coapplication of pesticides is a concern. Field trials were conducted to evaluate the compatibility of diclosulam with other herbicides and fungicides. Horseweed control by diclosulam in combination with glyphosate, sulfosate, or paraquat was compared to combinations of these herbicides with flumioxazin, tribenuron plus thifensulfuron, or 2,4-D. All treatments that contained diclosulam controlled horseweed at least 86%. Broadleaf signalgrass control by clethodim and sethoxydim was not affected by diclosulam; however, large crabgrass control was reduced when graminicides were coapplied with diclosulam. Common ragweed control was reduced when diclosulam was applied with chlorothalonil and pyraclostrobin but not by azoxystrobin or tebuconazole.

Research was conducted in North Carolina to compare weed control by various rates of imazapic POST alone or following diclosulam PRE. In a second experiment, weed control by imazapic applied POST alone or with acifluoren, diclosulam, or 2,4-DB was compared. In a final experiment, yellow nutsedge control by imazapic alone and with the fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole was compared. Large crabgrass was controlled more effectively by imazapic POST than diclosulam PRE. Common lambsquarters, common ragweed, and eclipta were controlled more effectively by diclosulam PRE than imazapic POST. Nodding spurge was controlled similarly by both herbicides. Few differences in control were noted when comparing imazapic rates after diclosulam PRE. Applying either diclosulam PRE or imazapic POST alone or in combination increased peanut yield over nontreated peanut in five of six experiments. Few differences in pod yield were noted when comparing imazapic rates. Acifluorfen, diclosulam, and 2,4-DB did not affect entireleaf morningglory, large crabgrass, nodding spurge, pitted morningglory, and yellow nutsedge control by imazapic. Eclipta control by coapplication of imazapic and diclosulam exceeded control by imazapic alone. The fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole did not affect yellow nutsedge control by imazapic.

Experiments were conducted from 2003 through 2006 to compare annual grass control by graminicides applied alone or with other pesticides and to determine whether graminicide formulation affected annual grass control and interactions with co-applied pesticides. Formulation and rate had no affect on broadleaf signalgrass or large crabgrass control by clethodim. The efficacy of clethodim in tank mixtures with acifluorfen plus bentazon, bentazon, chlorothalonil, imazapic, pyraclostrobin, or tebuconazole were not affected by clethodim formulation. Broadleaf signalgrass and large crabgrass control by clethodim was slightly reduced by acifluorfen plus bentazon, chlorothalonil, imazapic, and pyraclostrobin, but not by tebuconazole. Chlorothalonil and pyraclostrobin reduced broadleaf signalgrass control with quizalofop-P but did not reduce fall panicum control. Azoxystrobin, propiconazole, and tebuconazole did not affect efficacy of quizalofop-P.

Field studies were conducted to evaluate weed control with combinations of glyphosate at 750 g ae/ha and the insecticides acephate (370 g ai/ha), dicrotophos (370 g ai/ha), dimethoate (220 g ai/ha), fipronil (56 g ai/ha), imidacloprid (53 g ai/ha), lambda-cyhalothrin (37 g ai/ha), oxamyl (280 g ai/ha), or endosulfan (420 g ai/ha) and insect control with coapplication of the herbicide with insecticides acephate, dicrotophos, dimethoate, and imidacloprid. Applying lambda-cyhalothrin or fipronil with glyphosate reduced control of hemp sesbania by 19 and 9 percentage points, respectively, compared with glyphosate alone. Acephate, dicrotophos, dimethoate, imidacloprid, lambda-cyhalothrin, oxamyl, and endosulfan did not affect hemp sesbania, pitted morningglory, prickly sida, and redweed control by glyphosate. Lambda-cyhalothrin and fipronil did not affect glyphosate control of weeds other than hemp sesbania. Addition of glyphosate to dicrotophos improved cotton aphid control 4 d after treatment compared with dicrotophos alone. Thrips control was improved with addition of glyphosate to imidacloprid. Insect control was not reduced by glyphosate regardless of insecticide.

Experiments were conducted in North Carolina during 2002 and 2003 to evaluate broadleaf signalgrass and large crabgrass control by clethodim and sethoxydim applied in two-, three-, or four-way mixtures with fungicides, insecticides, and foliar fertilizer–plant growth regulator treatments. Broadleaf signalgrass and large crabgrass control by clethodim and sethoxydim was not reduced by the insecticides esfenvalerate, indoxacarb, or lambda-cyhalothrin. The fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole reduced large crabgrass control by clethodim or sethoxydim in one or more of three experiments for each herbicide. Disodium octaborate and the plant growth regulator prohexadione calcium plus urea ammonium nitrate (UAN) mixed with clethodim and fungicides improved large crabgrass control in some experiments. In contrast, prohexadione calcium plus UAN and disodium octaborate did not affect broadleaf signalgrass or large crabgrass control by sethoxydim.

Field trials were conducted in 2005 and 2006 to evaluate application of glyphosate alone or plus the plant growth regulator mepiquat chloride with 20 different insecticides to second-generation glyphosate-resistant cotton at the pinhead square or first bloom growth stages. At 7 DAT, averaged across cotton growth stages and herbicide treatments, combination with insecticides profenofos and methomyl resulted in 5 and 9% plant injury, respectively, and were the only insecticide combinations that resulted in injury greater than glyphosate or glyphosate plus mepiquat chloride applied alone. By 14 DAT, cotton injury was less than 2% for all treatments. Averaged across cotton growth stages and insecticides, addition of mepiquat chloride to glyphosate resulted in a 4 and 6 cm height reduction at 7 and 28 DAT, respectively. Seed cotton yield and percent first harvest were similar for all treatments, indicating that cotton injury and height reductions observed after application did not result in yield reductions or maturity delays. Glyphosate combined with insecticides and mepiquat chloride, in accordance with herbicide labeling for second-generation glyphosate-resistant cotton, offers producers the ability to integrate pest and crop management strategies and reduce application costs with minimal effect on the crop.

Coapplication of herbicides and insecticides affords growers an opportunity to control multiple pests with one application given that efficacy is not compromised. Trifloxysulfuron was applied at 5.3 g ai/ha both alone and in combination with the insecticides acephate (370 g ai/ha), oxamyl (370 g ai/ha), lambda-cyhalothrin (34 g ai/ha), acetamiprid (45 g ai/ha), thiamethoxam (45 g ai/ha), endosulfan (379 g ai/ha), indoxacarb (123 g ai/ha), emamectin benzoate (11 g ai/ha), methoxyfenozide (67 g ai/ha), spinosad (75 g ai/ha), and pyridalyl (112 g ai/ha) to determine the effects of coapplication on control of some of the more common and/or troublesome broadleaf weeds infesting cotton. In addition, the insecticides acephate, oxamyl, lambda-cyhalothrin, thiamethoxam, and endosulfan, at the rates listed above, were applied either alone or in combination with trifloxysulfuron at 7.9 g/ha to assess the effects of coapplication on thrips control. Control of hemp sesbania (insecticides oxamyl and lambda-cyhalothrin), sicklepod (insecticides methoxyfenozide and pyridalyl), redroot pigweed (insecticides thiamethoxam, methoxyfenozide, spinosad, and pyridalyl), and smooth pigweed, Palmer amaranth, and common lambsquarters (all insecticides) with trifloxysulfuron may be reduced when coapplied with the indicated insecticides for each species. Control of pitted, tall, ivyleaf, and entireleaf morningglory with trifloxysulfuron was not affected by the insecticides evaluated. Coapplication of trifloxysulfuron with the insecticides evaluated also resulted in no negative effects on thrips control.

A study was conducted in 2004 to determine the effect of coapplication of the insecticides acephate, acetamiprid, bifenthrin, cyfluthrin, cypermethrin, dicrotophos, dimethoate, emanectin benzoate, imidacloprid, indoxacarb, lambda-cyhalothrin, methoxyfenozide, spinosad, thiamethoxam, and zeta-cypermethrin; the plant growth-regulator mepiquat pentaborate; a foliar sodium calcium borate micronutrient solution; and a foliar nitrogen fertilizer solution with glyphosate on the efficacy of weeds that commonly infest cotton. Barnyardgrass, hemp sesbania, johnsongrass, pitted morningglory, and sicklepod were grown in outdoor containers and treated with glyphosate at 1,120 g ai/ha alone or in coapplication at the three-to four- or seven-to eight-leaf growth stage. Glyphosate efficacy, based on visual control ratings at 7, 14, and 28 d after treatment (DAT) and fresh weight reduction of weed biomass at 28 DAT, was unaffected by chemical coapplication or application timing. Averaged across application timing and visual rating interval, glyphosate alone controlled barnyardgrass 97%, hemp sesbania 68%, johnsongrass 98%, pitted morningglory 68%, and sicklepod 89%. These results indicate that glyphosate coapplications evaluated offer producers the ability to combine pest and crop management strategies and reduce application costs without sacrificing control of weeds evaluated.