Plant growth regulators were evaluated on African ‘Tifway’ and common bermudagrass. The vegetative growth of mowed Tifway bermudagrass was suppressed 15 to 22% for 3 weeks by flurprimidol at 0.84 kg ai/ha while mowed common bermudagrass was suppressed 30 to 34% during the same period by flurprimidol at 1.1 kg/ha. When nonmowed bermudagrass was treated with flurprimidol, the growth of Tifway treated at 0.84 kg/ha was suppressed 42% at 8 weeks while growth of common bermudagrass treated at 1.1 kg/ha was suppressed 26% at 6 weeks. Excessive injury by flurprimidol occurred when common and Tifway bermudagrass were treated at rates above 1.1 and 0.84 kg/ha, respectively. Imazethapyr excessively injured both bermudagrass cultivars. Mefluidide and Mon 4620 injured both bermudagrass cultivars slightly, but neither suppressed vegetative growth as effectively as flurprimidol.

Naptalam at 6.7 kg ae/ha applied with chloramben at 2.0 to 4.5 kg ae/ha was a safener for chloramben phytotoxicity to cucumber as expressed by increased dry weight in the greenhouse and yield in the field, but the protection was inadequate to be commercially acceptable. Naptalam applied in seed coatings also protected cucumber from chloramben phytotoxicity in the greenhouse but were ineffective in the field. Delaying chloramben application 24 to 72 h after naptalam application in the field increased the safening effect to a level that may be commercially acceptable. The safening effect was only to cucumber as effective weed control was achieved with chloramben and naptalam.

Field and greenhouse experiments were conducted to determine effects of adding (NH4)2SO4 or urea ammonium nitrate containing 30% N (UAN) and/or substituting BCH 81508 S for crop oil with sethoxydim and sethoxydim plus bentazon applied to corn and large crabgrass. Control was similar with sethoxydim plus crop oil and sethoxydim plus BCH 81508 S. Adding (NH4)2SO4 or UAN moderately improved control with sethoxydim in some experiments. Both (NH4)2SO4 and UAN increased control when added to sethoxydim plus bentazon, with UAN being the more effective ammonium fertilizer. Large crabgrass control with sethoxydim plus bentazon was enhanced more with 1.4 and 2.8 kg/ha (NH4)2SO4 than with 5.6 kg/ha. Substituting BCH 81508 S for crop oil with sethoxydim plus bentazon also increased corn and large crabgrass control. Adding ammonium fertilizers plus substituting BCH 81508 S for crop oil with sethoxydim plus bentazon eliminated antagonism on corn and partially alleviated antagonism on large crabgrass.

Antagonism was evaluated among four grass and seven broadleaf herbicides applied postemergence for seedling and rhizome johnsongrass control in soybeans. Imazaquin and chlorimuron were most antagonistic to grass herbicides. Haloxyfop and quizalofop were least affected by the addition of broadleaf herbicides. Johnsongrass control was reduced 11 to 46% when grass herbicides were applied with broadleaf herbicides and were evaluated 3 and 12 weeks after treatment (WAT).

Field studies were conducted on a Crowley silt loam under weed-free conditions to determine herbicidal tolerance of ‘Centennial’ soybeans. Early season phytotoxicity and mature plant height reductions were caused by imazaquin at 140 g ai/ha applied preemergence (PRE) followed by imazaquin applied postemergence (POE) at both 140 (labeled rate) and 280 g/ha and for metribuzin plus chlorimuron at 360 plus 60 g ai/ha PRE followed by chlorimuron POE at 18 g/ha (double rate). Soybean yields, averaged across 3 yr, were reduced only for metribuzin plus chlorimuron PRE followed by chlorimuron POE at both 9 and 18 g/ha (10 and 15%, respectively).

The effect of three rates of metolachlor on ‘Prime Time’ and ‘Tastie’, early maturing, fresh-market cabbage was evaluated in two geographically distinct regions of New York in 1986 and 1987. Metolachlor, when applied at 1.1, 1.7, and 2.2 kg ai/ha either pretransplant or 48 h after transplanting, caused no observable negative effects on either cabbage variety in either year when grown on sandy loam soils on Long Island. On a central New York silt loam soil, injury from metolachlor at 1.7 and 2.2 kg/ha applied post-transplant was negligible and transient. Metolachlor applied post-transplant caused a delay in maturity of Tastie cabbage in both years but not Prime Time; however, total yields equalled those of the weed-free controls with both varieties. Metolachlor applied pretransplant frequently caused excessive and persistent injury and often reduced cabbage yields.

Field studies were conducted in 1984, 1985, and 1986 to compare standard flat fan nozzles, low-volume flat fan nozzles, rotary controlled droplet applicators, and air-assisted nozzles for postemergence weed control in onions with oxyfluorfen and fluazifop-P. Herbicides applied with flat fan nozzles at 47 or 190 L/ha controlled broadleaf and grass weeds as good or better than with the other nozzles. Oxyfluorfen applied with flat fan nozzles controlled common lambsquarters and ladysthumb best. None of the nozzles improved control of the difficult marsh yellowcress. Carrier volume had minimal effect on weed control. Nozzle and carrier volume did not affect onion yield.

A surface-roller wiper that rotates by direct contact with the ground was developed to apply herbicides to broadleaf weeds in turf. The free-wheeling roller 1.8 m wide consists of a 30-cm diam PVC pipe covered with a 1.3-cm thick carpet The herbicide is delivered by gravity to the carpet through a pipe manifold. Broadleaf weeds in turf were effectively controlled with 2,4-D roller applied once as a 2% solution (2.2 kg ae/ha) or twice as a 1% solution (1.1 kg/ha). Herbicide drift was avoided with the roller applicator as indicated by lack of injury to tomato plants downwind from 2,4-D roller applied as a 5% (5.6 kg/ha) solution.

Cold stress and field studies were conducted to determine the effects of alachlor, metolachlor, butylate plus dichlormid, and EPTC plus dichlormid on germination and seedling vigor of 30 sweet corn cultivars with three commercially important endosperm mutants (su, se, and sh2). Seedling emergence from cool soils was best when treated with EPTC plus dichlormid and alachlor and was decreased 11% by metolachlor and butylate plus dichlormid. The se and sh2 endosperm mutants were injured the most by the herbicides. Plant size was reduced by the thiocarbamate herbicides but not by the chloracetamides.

Field and greenhouse studies were conducted to evaluate the following growth regulators: ABG-3034, a cytokinin, benzylaminopurine (BAP); alkanolamine salt of 2,4-D; gibberellic acid (GA); isopropylamine salt of glyphosate; kinetin; napthaleneacetic acid (NAA); and PP333, an experimental antigibberellin compound, and the herbicides: dimethylamine salt of dicamba and potassium salt of picloram alone and combined on the growth and control of leafy spurge. The results of greenhouse and field studies show that growth regulators did not enhance the performance of herbicides in controlling leafy spurge.

The importance of tall fescue as a pasture grass is diminished when infected with the fescue endophyte. The availability of fungus-free seed has necessitated the development of systems to kill the infected sod before interseeding fungus-free seed. Field studies were conducted to evaluate the response of fescue sod to foliar-applied herbicides as single and sequential applications during the fall and spring. Sequential applications of paraquat at 0.14, 0.28, and 0.56 kg ai/ha in September and October and glyphosate at 0.84 and 1.7 kg/ha applied as single or sequential applications in September and October resulted in more than 90% kill of the tall fescue sod. Spring treatments of paraquat and glyphosate were less effective than those applied in the fall. Dalapon, fluazifop-P, HOE-39866 [glufosinate (proposed name)], sethoxydim, and simazine did not effectively kill the sod.

In field experiments, chlorsulfuron and CGA 131036 did not injure winter wheat. Both herbicides applied postemergence at 9 and 10 g ai/ha completely controlled flixweed. CGA 131036 controlled cutleaf eveningprimrose 81%, and chlorsulfuron controlled 91%. At similar rates, CGA 131036 was also less effective than chlorsulfuron on henbit and Italian ryegrass. Both controlled wild buckwheat 77% when applied postemergence at 18 g/ha. Neither of the sulfonylurea herbicides controlled prostrate spurge or woolly croton as effectively as 2,4-D. In a bean root bioassay, root growth inhibition by both herbicides was partially alleviated by adding isoleucine and valine.

A 2-yr study was conducted to evaluate the response of yellow starthistle density and grass biomass to combinations of newly seeded grass, picloram, and fertilizer. A combination of ‘Tualatin’ tall oatgrass or ‘Paiute’ orchardgrass with 0.14 or 0.28 kg ae/ha of picloram effectively controlled yellow starthistle and improved forage production. Grass seeded alone or combined with fertilizer neither controlled yellow starthistle nor improved forage production. Three-way combinations of grass, picloram, and fertilizer did not affect yellow starthistle density in either year but resulted in more ‘Tualatin’ tall oatgrass biomass in 1987.

Fluometuron at 1.1 kg ai/ha was applied postemergence (over-the-top) to cotton in the V3 to V4 stage to determine effects on flower and boll production, yield, and fiber quality. Treated plants produced more bolls but boll weight was reduced. Lint yield was not affected. Flower and boll production during the first 2 weeks of flowering were reduced, but treated plants produced more flowers and bolls during mid- and late bloom. A delay in sympodia development delayed development of fruiting structures. Fluometuron treatment promoted sympodia development on monopodia at nodes three and four. Fiber micronaire was reduced in 1 of 2 yr. Fiber strength, length, and length uniformity were not affected.

A mixture of 2,4-D with either thiameturon, DPX-L5300, or DPX-R9674 controlled common chickweed in winter wheat better than 2,4-D alone. None of these herbicides affected wheat height, lodging, or yield. Similarly, no significant differences in wheat height or lodging occurred among seeding rates. Wheat sown near South Charleston, OH, at a seeding rate of 67 kg/ha yielded significantly less than that sown at 100 or 134 kg/ha; however, there was no difference in wheat yield among seedling rates at a second location near Columbus, OH.

This study was conducted to determine if ‘Pensacola’ bahiagrass, a major weed in turf and pastures in the southeastern United States, could be eliminated selectively from centipedegrass and ‘Tifway’ bermudagrass turf and a ‘Coastal’ bermudagrass pasture by treating with sulfometuron. Established Pensacola bahiagrass usually was controlled satisfactorily in Tifway bermudagrass and centipedegrass turf and in a Coastal bermudagrass pasture with sulfometuron at 210, 160, 105 g ai/ha applied twice, respectively. Bahiagrass seedlings were eliminated from both newly planted centipedegrass and Tifway bermudagrass turf with 105 g/ha sulfometuron applied once.

Nine field experiments were conducted from 1984 through 1988 to determine the effect on rice of imazaquin applied to soybeans the previous growing season. Imazaquin was applied preplant incorporated, preemergence, or postemergence at rates ranging from 70 to 560 g ai/ha. ‘Bond’, ‘Lemont’, ‘Mars', ‘Newbonnet’, and ‘Tebonnet’ rice were planted the following year. Across all locations, years, cultivars, soil series, methods of application, and imazaquin rates, rice injury symptoms were not observed, and rice grain yields were not reduced by imazaquin residues.

Acifluorfen, chlorimuron, and thiameturon were compared in single and sequential treatments for cowpea control in soybean. Chlorimuron applied once at 8.8 g ai/ha at 14, 21, and 28 days after cowpea emergence controlled 80% or more of cowpea. Control was greater at 14 and 21 than at 28 days after emergence in one of three experiments. Cowpea control by chlorimuron was similar with single and sequential treatments. Soybean injury was lower, and soybean seed yields generally were higher with chlorimuron than with thiameturon or acifluorfen. Thiameturon and acifluorfen controlled less than 60% of cowpea. Three weedy cowpea cultivars responded the same to chlorimuron, but cowpea recovery was substantial in 1 of 3 yr.

Spring-applied herbicides were evaluated in field studies conducted in 1985 through 1987 in western Nebraska for selective weed control in irrigated established alfalfa. Imazethapyr, norflurazon, pendimethalin, and prodiamine did not injure alfalfa but varied in their weed control spectrums. Overall weed densities were lowest in plots treated with norflurazon at 2.8 kg ai/ha and diuron at 1.8 kg/ha.