Herbicide treatments of tank mixtures or sequential applications were applied at different growth stages and compared with standard treatments for control of barnyardgrass [Echinochloa crus-galli (L.) Beauv. ♯ ECHCM], bearded sprangletop [Leptochloa fascicularis (Lam.) Gray ♯ LEFFA], and aquatic weeds in rice (Oryza sativa L. ‘Starbonnet’). Some herbicides injured rice more than the propanil (3’,4’-dichloropropionanilide) or molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) standards, but injury for all treatments was inconsequential. Postemergence tank mixture treatments that controlled barnyardgrass (two- to four-leaf stages), bearded sprangletop (two-leaf to tillering stages), and aquatic weeds better than standard treatments were propanil plus butachlor [N-(butoxymethyl)-2-chloro-2’,6,-diethylacetanilide], oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-δ2-1,3,4-oxadiazolin-5-one] thiobencarb {S-[(4-chlorophenyl)methyl]diethylcarbamothioate}, or pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine].

Field studies were conducted from 1992 through 1994 to evaluate application timing of seven postemergence (POST) broadleaf herbicides alone and in mixtures for control of eclipta and pitted morningglory. Imazethapyr and 2,4-DB did not control eclipta while AC 263,222 applied early postemergence (EPOST) at 0.07 kg/ha provided greater than 90% control in 2 of 3 yr. EPOST applications of bentazon, acifluorfen + bentazon, and pyridate controlled eclipta at least 92% all 3 yr. Lactofen applied EPOST at 0.28 kg/ha provided similar levels of eclipta control in 2 of 3 yr. Imazethapyr controlled pitted morningglory > 70% when applied EPOST. AC 263,222 controlled pitted morningglory a minimum of 83% when applied EPOST at 0.04 or 0.07 kg/ha. Pitted morningglory control was at least 85% with 2,4-DB applied alone or in a mixture with AC 263,222, acifluorfen, imazethapyr, lactofen, or pyridate. Effective weed control increased peanut yields up to 98% over the untreated check.

The effect of sequential hexane, ethyl acetate, and aqueous methanol extracts of ‘Regal’ sweetpotato periderm on seed germination of sweetpotato, proso millet, and seven weed species was studied. The hexane extract, which contained the nonpolar components of the periderm tissue, was least inhibitory. It inhibited velvetleaf, proso millet, black nightshade, and redroot pigweed germination, and maximum inhibition was 56% for black nightshade at 200 mg of periderm extracted ml–1. The ethyl acetate fraction was inhibitory to proso millet, velvetleaf, black nightshade, goosegrass, tall morningglory, coffee senna, and redroot pigweed. The estimated I50 for ethyl acetate ranged from 17 mg periderm extracted ml–1 for black nightshade to 201 mg ml–1 for coffee senna. Sweetpotato, tall morningglory, and eclipta germination was not inhibited by this extract at the concentrations tested. The aqueous methanol extract was much more inhibitory than the hexane or ethyl acetate extracts, and there was considerable variation between species in response to this extract The I50 estimates for the aqueous methanol extract were 0.5, 0.6, 2.8, 4.4, 5.1, 9.6, 15.7, 21.0, and 25.8 mg ml–1 for velvetleaf, proso millet, black nightshade, goosegrass, sweetpotato, tall morningglory, eclipta, coffee senna, and pigweed, respectively.

An experiment was conducted at four locations in North Carolina during 1994 and 1995 to evaluate weed control, cotton yield, fiber quality, and net returns in no-tillage bromoxynil-tolerant cotton. The experiment focused on using bromoxynil or pyrithiobac sodium applied early POST over-the-top as alternatives to fluometuron plus MSMA applied early POST directed. Fluometuron plus MSMA was more effective than bromoxynil or pyrithiobac sodium on tall morningglory, large crabgrass, goosegrass, and broadleaf signalgrass. Bromoxynil and fluometuron plus MSMA were similarly effective on common lambsquarters, common ragweed, and eclipta and more effective than pyrithiobac sodium. Pyrithiobac sodium and fluometuron plus MSMA were similarly effective on smooth pigweed and Palmer amaranth and more effective than bromoxynil. Prickly sida control by bromoxynil and pyrithiobac sodium was equal to or greater than control by fluometuron plus MSMA. All early POST herbicides controlled pitted morningglory similarly. Regardless of the early POST herbicides used, fluometuron applied PRE and cyanazine plus MSMA applied late POST directed increased control of most weeds and increased cotton yield and net returns. Bromoxynil and pyrithiobac sodium effectively substituted for fluometuron plus MSMA only in systems that included fluometuron applied PRE and cyanazine plus MSMA applied late POST directed. Effects of herbicide systems on cotton fiber quality were minor.

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.

Sensitivity of 49 tomato cultivars and four weeds to DPX-E9636 was determined in greenhouse experiments. Cultivar tolerance varied from completely tolerant to intolerant. The most efficacious application method in greenhouse experiments was early POST for the weeds tested (yellow nutsedge, prostrate eclipta, and paraquat-resistant and -sensitive American black nightshade). Paraquat-resistant American black nightshade was 123 times more sensitive to DPX-E9636 than the paraquat-sensitive biotype. Under field conditions and at 0, 36, or 72 g ai/ha applied one week after transplanting, tomato cultivars showed no response to DPX-E9636 in visual vigor ratings 3 wk treatment, or in shoot fresh or dry weight 4 wk after treatment.

Controlled environmental chamber experiments were conducted for a 14-d incubation period to measure the effect of temperature, light, light intensity, water potential, and pH on eclipta seed germination. In full light, seed germinated over a range of 10 to 35 C; however, germination was highest at 83% at 35 C. Seeds were strongly photoblastic with none germinating in the dark. Seeds germinated in light intensities between 6 and 100% of full light. Seeds germinated 78 to 88% in water potentials of 0.0, −0.1, and −0.2 MPa. In distilled water (pH ∼ 5.5) and a buffered solution pH 6 and 7, seeds germinated 85 to 89%; however, some seeds germinated in a buffered solution pH range of 5 to 8. After the first 14-d incubation period, ungerminated seeds were transferred to distilled water and incubated at 35 C in full light for 4 to 6 d as a second incubation period. Seeds germinated 89 to 96% after this second incubation period when first incubation was at temperatures 10 to 35 C in full light or darkness, light intensities 0 to 100% of full light, water potentials 0.0 to −0.8 MPa, and buffered solution pH levels of 5.5 to 7.

Field studies were conducted at five locations in North Carolina and Virginia in 1996 and 1997 to evaluate weed control and peanut (Arachis hypogaea) response to diclosulam that was applied preemergence (PRE) and in systems with commercial standards. All plots received a preplant incorporated (PPI) treatment of ethalfluralin at 840 g ai/ha. Diclosulam controlled common lambsquarters (Chenopodium album L.), eclipta (Eclipta prostrata L.), entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray), ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.], pitted morningglory (Ipomoea lacunosa L.), and prickly sida (Sida spinosa L.) as well as and frequently better than the commercial standards of acifluorfen plus bentazon applied postemergence (POST), paraquat plus bentazon early POST followed by (fb) imazapic POST, or imazapic POST. Systems with ethalfluralin PPI plus diclosulam PRE 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 PRE at 17, 26, or 35 g/ha.

Transplanted cabbage was grown in conventional-tillage (100% cultivated) and strip-tillage (25% cultivated and 75% residue) production systems with various herbicide treatments to evaluate weed control and cabbage yield. DCPA at 9 kg ai/ha, napropamide at 1.1 kg ai/ha, oxyfluorfen at 0.3 kg ai/ha, and oxyfluorfen at 0.2 kg ai/ha plus napropamide at 1.1 kg ai/ha provided commercially acceptable (> 80%) control of carpetweed, swinecress, large crabgrass, redroot pigweed, and common lambsquarters under both tillage systems. However, only oxyfluorfen plus napropamide provided control of eclipta. At a second location, all herbicides controlled common purslane and barnyardgrass and all but DCPA controlled hairy galinsoga. Overall, cabbage yields were the same between conventional and strip-tillage systems, and among herbicide treatments when average cabbage head weights across tillage method were pooled.

Efficacy of herbicide programs containing clomazone PPI plus fluometuron PRE or clomazone plus pendimethalin PPI plus fluometuron PRE was compared with that of standard programs of pendimethalin PPI plus fluometuron PRE and norflurazon PPI plus norflurazon and fluometuron PRE. Cotton injury was less than 5% with all treatments when disulfoton or phorate was applied in the seed furrow. Control of fall panicum, goosegrass, large crabgrass, eclipta, entireleaf morningglory, ivyleaf morningglory, pitted morningglory, tall morningglory, prickly sida, redroot pigweed, smooth pigweed, hemp sesbania, spotted spurge, sicklepod, and velvetleaf and cotton yields with 0.8 kg ai ha−1 of clomazone plus fluometuron or 0.6 kg ha−1 of clomazone plus pendimethalin plus fluometuron equalled or exceeded that from the standard herbicide programs. POST-directed application of methazole at 0.8 kg ai ha−1 plus MSMA at 2.2 kg ae ha−1 increased sicklepod and morningglory control and cotton yield. Clomazone applied PRE at 0.6 kg ha−1 with fluometuron controlled broadleaf signalgrass, goosegrass, large crabgrass, prickly sida, and smooth pigweed equally with that of standard treatments of trifluralin or trifluralin plus norflurazon PPI and fluometuron PRE, whereas pitted morningglory control and cotton yield with clomazone plus fluometuron exceeded that with the standards.