A pine kraft lignin (PC940C) controlled the release of 14C-chloramben (3-amino-2,5-dichlorobenzoic acid), 14C-metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one], and 14C-alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] as measured by water leaching in soil columns. As more PC940C was used, a concentration effect was found with more of the three herbicides being retained in the top portion of the soil columns. Combinations of alachlor and metribuzin applied with PC940C did not alter the retention in the top portion of the soil columns of either 14C-metribuzin or 14C-alachlor compared to each herbicide applied with PC940C alone. This would suggest that, at the rate of PC940C used, there was no competition between either herbicide for the controlled-release function of PC940C. The percentage of 14C-chloramben, 14C-metribuzin, and 14C-alachlor retained by PC940C in the top portion of the columns was very similar. Combinations of metribuzin and alachlor without PC940C reduced the mobility of both 14C-metribuzin and 14C-alachlor. Finally, 3H-PC940C was found to be immobile in soil columns leached with water.

The relationship between herbicide injury and soybean [Glycine max (L.) Merr. ‘Amsoy 71’] yield response was studied under weed free conditions at three locations. Reduced crop vigor at early growth stages was not an adequate indicator of yield response. Yield reduction was greater when soybean stand was reduced by herbicides than when stand was reduced to the same level by hand thinning. Yield response was a function of the degree and persistence of crop vigor reduction in a reduced stand of soybeans.

Studies determined the effect of common lambsquarters, goosegrass, and a mixture of these on ‘Beauregard’ and ‘Jewel’ sweetpotato transplant production with or without polyethylene bed covers. Effects of herbicides on Beauregard in propagation beds were also studied. Black and infrared transmissible (IRT) plastic covers gave near 100% control of goosegrass and common lambsquarters, resulting in the greatest number and weight of Jewel transplants per plot. Common lambsquarters reduced transplant number and weight per plot with Jewel under clear plastic covers when compared with black and IRT plastic covers. Beauregard transplant number was not affected by row cover treatment. However, with data combined over all covers, Beauregard transplant weight per plot was lowest for treatments with weeds compared to weed-free plots. With the exception of DCPA, no significant (10% or greater) injury to Beauregard was observed with diphenamid, napropamide, chloramben, or chloramben plus fluazifop.

The response of sweet white lupin to several herbicides was evaluated over five years at Charlottetown, Prince Edward Island (PEI) and two years at Cornhill, New Brunswick (NB). Excellent crop tolerance was found to the herbicides: chloramben, ethalfluralin, fluazifop-P, linuron, metobromuron, metolachlor, and trifluralin. None of the above herbicides affected crop grain yield or 1000 seed weight. Sweet white lupin was slightly injured by metribuzin at 500 g ai/ha but yields and 1000 seed weight were not affected. Higher rates of metribuzin reduced lupin yield and 1000 seed weight. Imazethapyr applied POST with 0.25% v/v Agral 90 and 1.0% v/v 28% N fertilizer caused severe crop injury and reduced lupin yields.

Preemergence application of chloramben (3-amino-2,5-dichlorobenzoic acid) at 5.0 and 6.7 kg/ha, chlorbromuron [3-(4-bromo-3-chlorophenyl)-1-methoxy-1-methylurea] at 2.2 kg/ha, and linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] + nitralin [4-(methyl-sulfonyl)-2,6-dinitro-N,N-dipropylaniline] at 1.1 + 1.1 kg/ha controlled 95% or more of the barnyardgrass [Echinochloa crus-galli (L.) Beauv.], common lambsquarters (Chenopodium album L.), red-root pigweed (Amaranthus retroflexus L.), Powell amaranth (A. powellii S. Wats.), and hairy nightshade (Solanum sarachoides Sendt.), but reduced stands and injured direct-seeded asparagus (Asparagus officinalis L. ‘UC-66’). Linuron at 1.1 kg/ha controlled only 84% of the barnyardgrass and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] at 0.6 kg/ha controlled about 50% of the hairy nightshade. Activated carbon applied at 56 and 112 kg/ha in a 3-cm band over the seeded row protected the asparagus from chloramben at 5.0 kg/ha, chlorbromuron at 2.2 kg/ha, and linuron + nitralin at 1.1 + 1.1 kg/ha. Weed control generally was reduced about 10% in the carbon band, but control was still 85 to 90%. Metribuzin reduced asparagus stands and vigor severely, even when 112 kg/ha of activated carbon was applied.

Weed control in no-till soybeans [Glycine max (L.) Merr. ‘Wells’] planted into shredded corn (Zea mays L.) residue was evaluated at Concord, NE, over a 3-yr period. Herbicide factors evaluated were time of herbicide application for no-till soybeans, efficacy of glyphosate [N-(phosphonomethyl)glycine] relative to paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) for control of emerged weeds, and the efficacy of alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] for residual weed control. Combination residual and contact herbicide treatments were applied either as a preplant surface application or preemergence after no-till-planted soybeans. Removal of existing weed growth was not consistently better with the preplant surface application compared to later removal after soybean planting. Paraquat and glyphosate gave nearly equal control of emerged weeds. Addition of 2,4-D [(2,4-dichlorophenoxy)acetic acid] with paraquat in the tank mix did not improve weed control. Use of narrow, ripple coulters on the no-till planter resulted in minimal disturbance of the preplant surface herbicide so that additional preemergence herbicide at planting was seldom beneficial.

Field research was conducted at Arlington, WI, and Janesville, WI, in 1986 and 1987 to evaluate the effect of conventional-tillage, chisel plow, and no-till systems on the density and control of annual weed species in solid-seeded soybean. Common lambsquarters densities were not greatly influenced by tillage systems, but redroot pigweed densities were generally highest in the chisel plow system. Conventional tillage always had greater velvetleaf densities than no-till and no-till always had greater giant foxtail densities than conventional tillage. Giant foxtail and redroot pigweed became more difficult to control when tillage was reduced, while velvetleaf became less of a problem. This response was not observed with all herbicide treatments evaluated and several herbicide treatments provided excellent weed control. Soybean yield was not affected by tillage systems under weed-free conditions and differences in soybean yield appeared to be due to differences in weed control.

Eight accessions of weedy nightshades representing five species were evaluated for response to four herbicides applied preemergence in growth chamber studies and four herbicides applied postemergence in greenhouse studies. Species differed in susceptibility to all herbicides evaluated. The largest differences were found with postemergence applications of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide}; hairy nightshade (Solanum sarrachoides Sendt. ♯ SOLSA) was relatively susceptible, but eastern black nightshade (S. ptycanthum Dun.) was very tolerant. S. ptycanthum, however, was one of the more susceptible species. It was always more susceptible than black nightshade (S. nigrum L. ♯ SOLNI) to all other herbicides evaluated.

Effects and interactions of two soil temperatures, 19 ± 1 and 27 ± 3 C, and seven soil-applied herbicide treatments on the morphological development and concentrations of eight essential nutrients in leaves, stems, and roots of pinto beans were determined. Soil temperature did not affect overall plant morphology but did affect some nutrient concentrations in the roots, stems, and leaves. Combinations of alachlor plus trifluralin at 2.2 plus 0.28 kg ai/ha and EPTC plus trifluralin at 2.2 plus 0.28 kg ai/ha caused greater negative effects than when the herbicides were applied separately. Oryzalin at 0.56 kg ai/ha and EPTC at 3.4 kg ai/ha induced the least number of morphological effects, while alachlor at 3.4 kg ai/ha, chloramben at 2.2 kg ai/ha, and trifluralin applied at 0.56 kg ai/ha produced an intermediate number. Alachlor, trifluralin, and combinations of alachlor plus trifluralin and EPTC plus trifluralin inhibited nodule growth. Each herbicide affected different nutrients. Alachlor plus trifluralin affected the level of each nutrient in at least one plant tissue. Many herbicide-soil temperature interactions occurred.

Field studies were conducted to determine if oxyfluorfen alone or combined with other herbicides could be applied between black polyethylene mulch without injuring muskmelon. Oxyfluorfen at rates up to 1.1 kg ai/ha did not injure muskmelon provided adequate rain or irrigation occurred to incorporate the oxyfluorfen thereby minimizing vapors that could injure muskmelon. Using this practice, muskmelon yields from oxyfluorfen-treated plots were the same as yields from untreated cultivated plots.

Six herbicides were evaluated at two rates on sweet potatoes [Ipomoea batatas (L.) Lam. ‘Georgia Red’, ‘Georgia Jet’] with and without cultivation from 1972 through 1976. Cultivation with a ground-driven rotary hoe about 2 weeks later improved the control of late-season broadleaf weeds such as Florida beggarweed [Desmodium tortuosum (Sw.) DC] and showy crotalaria (Crotalaria spectabilis Roth.). Cultivation improved weed control where vernolate (S-propyl dipropylthiocarbamate), DCPA (dimethyl tetrachloroterephthalate), and napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] were applied. The improved weed control in cultivated treatments resulted in increased sweet potato yields in 1972 and 1973, which also were the years with the highest weed populations.

Studies were conducted to determine the response of ‘Jewel’ sweetpotato in propagation beds to DCPA and napropamide. Napropamide at 2.2 and 4.4 kg ha–1 caused slight injury, and reduced plant number and weight when compared with the untreated control. Napropamide at 1.1 kg ha–1 combined with chloramben at 3.3 kg ha–1 was not injurious; plant production was equal to the untreated control, diphenamid at 4.4 kg ha–1, and chloramben at 3.3 kg ha–1. DCPA at 8.3 and 10.0 kg ha–1 caused unacceptable injury and reduced plant number and weight.