Field studies were conducted in 1996 and 1997 at Belleville and Pawnee, IL, to evaluate single and sequential applications of glufosinate on tolerance of glufosinate-resistant corn and annual weed control. Glufosinate caused 0 to 13% corn injury 7 days after treatment (DAT) and 0 to 6% corn injury 28 DAT. Injury was characterized as stunting with glufosinate. Glufosinate at 400 to 1,200 g ai/ha did not reduce final corn height or grain yield. At Pawnee in both years and at Belleville in 1996, a single application of glufosinate at 400 g/ha controlled giant foxtail, velvetleaf, ivyleaf morningglory, and common lambsquarters 85 to 100%. At Belleville in 1997, sequential applications of glufosinate provided greater weed control (87 to 100%) than a single application (0 to 63%) because of weed emergence after application. Weed control with a single application of glufosinate or with nicosulfuron plus bromoxynil was similar at both locations. Height and grain yield of glufosinate-resistant corn were not different from that of glufosinate-susceptible corn (isoline of glufosinate-resistant corn).

Experiments were conducted in 1985 and 1986 to determine and compare the efficacy, phytotoxicity, and soil persistence of imazquin, imazethapyr, and clomazone in no-till double-crop soybeans. All herbicides controlled 93% or greater jimsonweed, velvetleaf, and giant foxtail. Imazaquin and imazethapyr controlled more common cocklebur and ivyleaf morningglory than clomazone. Soybeans were injured from imazaquin and imazethapyr applications in 1986 but yields were not reduced. First-order kinetics described the dissipation of each herbicide. Imazaquin and imazethapyr were more persistent in the soil than clomazone. Averaged over both years, half-lives of 10, 43, and 60 days were calculated for clomazone, imazaquin, and imazethapyr, respectively. Clomazone was not detected 10 to 20 cm in the soil profile. More imazethapyr was detected 10 to 20 cm in the soil profile than imazaquin in 1985. Slight corn injury (≤10%) was observed in 1987 following previous year applications of imazaquin to no-till double-crop soybeans but corn yields were not reduced.

Ivyleaf morningglory weed-free period, weedy period, and density studies were conducted in 1993 and 1994 to determine the effects of soil-applied imazaquin and chlorimuron plus metribuzin on ivyleaf morningglory interference in soybean. A weed-free period of 4 wk was needed to maintain soybean yield equivalent to weed-free season long when herbicides were not used, but treatment with either chlorimuron plus metribuzin or imazaquin maintained yield comparable to weed-free at all intervals. Ivyleaf morningglory biomass was reduced by both herbicides across all weed-free periods. The period nontreated ivyleaf morningglory plants were tolerated without yield loss was only 2 wk, but this interval was extended to 8 wk after treatment with chlorimuron plus metribuzin or imazaquin. Without herbicides, soybean yield was reduced by four ivyleaf morningglory per m of row, but the highest population evaluated in this study (eight per m of row) did not reduce soybean yield after treatment with chlorimuron plus metribuzin or imazaquin. Ivyleaf morningglory biomass was reduced at all densities after treatment with either herbicide.

Soybean and ivyleaf morningglory were grown alone and together to quantify water use and growth after treatment with soil-applied chlorimuron plus metribuzin, imazaquin, or no herbicide. Soybean water consumption was 22 ml pot−1 day−1 or more when grown alone or with another soybean, regardless of herbicide treatment. Ivyleaf morningglory grown alone or with another ivyleaf morningglory consumed ≥ 32 ml water pot−1 day−1 when no herbicide was applied. Treatment with chlorimuron plus metribuzin or imazaquin reduced ivyleaf morningglory water consumption to ≤ 4 ml pot−1 day−1. Water use was reduced with either herbicide when soybean and ivyleaf morningglory were grown together, indicating little or no water consumption by ivyleaf morningglory. Ivyleaf morningglory height, root length, leaf area, and dry matter were reduced by imazaquin or chlorimuron plus metribuzin. Soybean leaf area was also reduced by herbicide treatment or the presence of another plant. Soybean biomass was not reduced in any planting combination, except when two soybean were grown together and treated with imazaquin. Nontreated ivyleaf morningglory partitioned more biomass into the shoots than roots. Ivyleaf morningglory responded to herbicide treatment by partitioning more biomass into roots.

Field studies were conducted over a four-year period to determine the weed control efficacy of ICIA-0051 and SC-0774 in no-tillage and conventional corn. Treatments consisted of both pre- and postemergence applications of ICIA-0051, alone and in combination with atrazine, and preemergence applications in combination with metolachlor. SC-0774 was applied preemergence, alone and in combination with atrazine. Results indicated good control of triazine-resistant (TR) smooth pigweed and other annual broadleaf weeds present with no adverse effects on crop vigor and yield with ICIA-0051. Generally, the addition of atrazine to ICIA-0051 improved weed control. SC-0774 provided good control of fall panicum, but generally poorer and less consistent control of giant ragweed, common ragweed, common lambsquarters, and ivyleaf and tall morningglory species.

Field studies were conducted at two locations in Missouri in 1990 and 1991 to evaluate control of velvetleaf, ivyleaf morningglory, and cocklebur in soybean with label rates (1×) or reduced rates (0.5×) of four PPI herbicides followed with or without cultivation and POST application of one fourth (0.25×) the label rate of imazethapyr. Weed control and soybean yield with the 0.5× rate of preplant clomazone, imazaquin, metribuzin, and metribuzin + chlorimuron followed by either cultivation or imazethapyr POST was equivalent to a 1× rate of the PPI herbicides followed by either cultivation or imazethapyr. Weed control and soybean yield with the 0.5× rates of the PPI herbicides without cultivation or POST imazethapyr were lower than with 1× rates of PPI herbicides.

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 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.