BAS-145-138 considerably muted the herbicidal effect of the sulfonylurea herbicides on corn. Decreases of 54 and 52% in shoot fresh and dry weight caused by 10 μM chlorsulfuron were countered almost completely by 1.5 mM BAS-145-138 with only a 10% loss in fresh weight and a 3% loss in dry weight. Similar strong antidotal influence by BAS-145-138 on chlorimuron was observed. BAS-145-138 partially protected corn against sulfometuron. Shoot fresh weight of corn treated with 0.2 μM sulfometuron was inhibited 88%, whereas adding 0.5 or 1.5 mM BAS-145-138 reduced inhibition to 52 and 24%, respectively.

For effective full-season control of dodder in alfalfa produced for seed, herbicides applied to soil in late winter or early spring should remain active through June. Pendimethalin or prodiamine at 2.2 kg ai ha-1 applied in mid March controlled 97 to 100% of dodder through May and 92 to 100% through June. At 3.4 kg ha-1, both controlled 96 to 100% of dodder through June each year, and control of 95 or 96% persisted through July in 1 of 3 yr. In the greenhouse, trifluralin was only about 1/8 as active against dodder as pendimethalin and prodiamine. In the field, trifluralin at 2.2 kg ai ha-1 controlled dodder satisfactorily through May in 3 of 4 yr and through June in 1 of 4 yr. At 4.5 kg ha-1, trifluralin controlled 99% of dodder through May in each of 3 yr; control was satisfactory through June in 2 of 3 yr. Oryzalin was less effective than the other three dinitroaniline herbicides. A standard herbicide, chlorpropham at 6.7 kg ai ha-1, controlled 97 to 100% of dodder through May, but control usually did not persist through June. Another standard herbicide, DCPA at 11.2 kg ai ha-1, controlled 97 or 98% of dodder through June in 2 of 3 yr. Pendimethalin and prodiamine at 3.4 and 6.7 kg ai ha-1 did not affect the yield or quality of seed produced by established alfalfa. Heavy sprinkler irrigation (15 cm of water) after application did not diminish dodder control from pendimethalin or prodiamine.

Field experiments were initiated to determine the efficacy of fluazifop as influenced by growth stage for green, yellow, and giant foxtail, large crabgrass, and Japanese millet. Additionally, the influence of air temperature and simulated rainfall on fluazifop efficacy for green foxtail and Japanese millet was determined by greenhouse and growth-room experiments. In both 1983 and 1984, fluazifop activity was reduced as the growth stage increased from 3- to 5- to 7-leaf for all species. Significant differences among species in susceptibility to fluazifop were evident with the descending order of tolerance: green foxtail > large crabgrass > yellow foxtail > giant foxtail > Japanese millet. Increasing the air temperature from 18 to 30 C reduced fluazifop control of green foxtail at herbicide rates less than 0.14 kg ai/ha but did not affect Japanese millet. A 1- to 2-h rain-free interval was required for optimum control of green foxtail and Japanese millet at 0.07 kg/ha fluazifop; the interval was reduced to 45 and 15 min, respectively, when fluazifop rates were 0.14 kg/ha. The longer rain-free interval required for optimum control of green foxtail compared to Japanese millet may reflect a slower rate of herbicide absorption in green foxtail.

Oxyfluorfen applied preemergence at 0.14, 0.28, and 0.56 kg ai/ha reduced stand of direct-seeded broccoli 40 to 99%, while BAS 514 applied at the same rates did not reduce stand. Broccoli plants that survived oxyfluorfen exhibited 32 to 97% injury 6 to 9 weeks after treatment. BAS 514 at 0.14, 0.28, and 0.56 kg ai/ha caused 6 to 35% crop injury. Oxyfluorfen at 0.28 and 0.56 kg/ha reduced yield compared to the cultivated check at all locations. At one location, all rates of BAS 514 reduced broccoli yield compared to the cultivated check. The two low rates of oxyfluorfen and the two high rates of BAS 514 delayed crop maturity approximately 1 week at one location.

The effect of atrazine rate and subsequent tillage on seedling alfalfa injury from atrazine carry-over was examined at two locations in Michigan. Atrazine concentration and alfalfa injury 1 yr after treatment were greater in the northern location than in the central Michigan location. At both locations, alfalfa injury was significantly greater under no-tillage than moldboard plowing. With no-tillage, alfalfa was injured more in the area between the previous corn rows than within the rows. Analysis of soil samples collected from within corn rows and between rows showed higher atrazine concentration between the corn rows.

Experiments were conducted in the greenhouse and the field to determine the influence of various oil adjuvants on small grain and grass weed susceptibility to foliarly applied BAS-514 OO H (BAS-514). Barnyardgrass, green foxtail, and yellow foxtail were more susceptible to BAS-514 at 0.56 kg ai ha-1 applied with than without an oil adjuvant. Shoot fresh weight reductions of barnyardgrass, green foxtail, and yellow foxtail were greater when BAS-514 at 0.56 kg ha-1 was applied with a methylated seed oil than with a petroleum oil adjuvant in the greenhouse. Differences in the effectiveness among oil adjuvants in enhancing BAS-514 phytotoxicity were more evident in greenhouse than in field experiments. Oil adjuvant enhancement of BAS-514 varied with plant species. Oats, hard red spring wheat, and winter wheat tolerated BAS-514 at 1.1 kg ha-1 foliarly applied with or without an oil adjuvant in the greenhouse. BAS-514 at 0.56 kg ha-1 applied with oil adjuvants caused less than 5% injury to wheat in the field.

Weed control and red pine release by spotgun-applied hexazinone in a northern Ontario plantation were evaluated 3 yr after treatment, while hexazinone residues and lateral movement in the sandy loam soil were determined 1 yr after treatment. Hexazinone, grid pattern spot applied at 480 mg ai/spot, approximating 1.6 kg ai/ha, resulted in 88% quaking aspen stem dieback and variable suppression of white birch and pin cherry. The height and basal diam of treated red pine were 131 and 150% of control, respectively, after 3 yr. Hexazinone residues were reduced to 1% at the treated spot and did not move laterally beyond 0.5 m, 1 yr after treatment. Detection of small amounts of metabolites A and B (0.2 and 0.3%) indicated the non-cumulative degradation of hexazinone in soils.

Mediterranean saltwort has become an established weed in the upper San Joaquin Valley and the Temblor Range areas of California. Fifteen herbicides were evaluated to determine their effects on 6- to 8-week-old plants grown in the greenhouse. Mediterranean saltwort was killed by chlorsulfuron3, hexazinone, and metribuzin at low rates. Triclopyr4 (Garlon 3A and Garlon 4), atrazine, imazapyr, glyphosate, dicamba, bromacil, karbutilate, and simazine were effective at higher rates. Four herbicides, asulam, pendimethalin, amitrole, and fosamine, did not kill Mediterranean saltwort at the rates tested.

A rapid increase in the number of herbicides and herbicide mixtures registered for use in row crops has made herbicide selection difficult. WEEDS is a computer program that enables a weed management expert to build a list of recommended herbicides or herbicide mixtures based upon weed species, soil texture, and soil organic matter content. An example is given for soybeans.

Dinitroaniline herbicides are major herbicides used to control annual grass weeds in cool-season turfgrasses. At least three herbicides, benefin, pendimethalin, and trifluralin are labeled preemergence to control weeds in established turfgrass. Prodiamine could be a competitive product. Benefin at 2.2 to 3.4 kg ai/ha, pendimethalin at 1.7 to 3.4 kg ai/ha, prodiamine at 0.6 to 1.7 kg ai/ ha, and benefin plus trifluralin at 1.1 plus 0.6 to 2.3 plus 1.1 kg ai/ha effectively control many annual grass weeds, including large and smooth crabgrass, yellow and green foxtail, barnyardgrass, goosegrass, fall panicum, and annual bluegrass. Most dinitroaniline herbicides provide residual preemergence weed control for the entire growing season. In general, Kentucky bluegrass, perennial ryegrass, tall fescue, red fescue, and other cool-season turfgrasses tolerate most of these herbicides, although higher-than-normal rates of any dinitroaniline herbicide could restrict root growth and cause stand thinning in turfgrass species.

The behavior and dissipation of 26 dinitroaniline herbicides in soils are reviewed. Some of the compounds also are referred to as dinitrotoluidines, -benzen(e)amines, -benzenediamines, -cumidines, -benzenesulfonamides, -acetophenones, and sulfonylsulfilimines. All dinitroanilines are sorbed to soil particles, particularly to organic or humic substances, and are nearly immobile in soils. Soil K values range from 7 to 117 and KOC values range from 80 to 471 000. Compounds with vapor pressures greater than 50 × 10-6 mm of Hg at ambient temperatures were reported to volatilize and diffuse through, and out of, the soil in significant amounts, depending on temperature and moisture conditions. Greater losses occurred from warm, moist soils than from cool, dry soils. Photodecomposition of dinitroanilines on soil surfaces was low but occurred when the chemicals were present in the vapor state or in aqueous solutions. Bioavailability of the chemicals decreased as organic matter contents of the soils increased. Dinitroaniline herbicides were degraded primarily by soil microorganisms, and fungi were the major organisms involved. Degradation proceeded faster under anaerobic conditions than under aerobic conditions and faster under warm, moist conditions than under cool, dry conditions. Half-life values for dinitroanilines ranged from 7 to 27 days under anaerobic conditions and from 19 to 132 days under aerobic conditions. The chemicals did not affect most soil microflora; and any significant effects reported were of short duration.

Wild-proso millet control in furrow-irrigated corn was evaluated in Colorado and Nebraska in 1986 and 1987. No single herbicide alone controlled wild-proso millet all season. In Colorado, EPTC applied preplant incorporated followed by cyanazine plus pendimethalin applied early postemergence controlled 94% of wild-proso millet. Acetochlor applied preemergence followed by cyanazine plus pendimethalin applied early postemergence controlled wild-proso millet better all season (93%) than alachlor (81%) or metolachlor (71%) followed by the same early postemergence strategy. Successful Colorado wild-proso millet management treatments (>85% season-long control) increased corn yields an average of 3260 kg ha-1 compared to the untreated control. To obtain wild-proso millet control of 90% or more in Nebraska in 1986, alachlor, cycloate, EPTC, and metolachlor applied had to be combined with cyanazine plus pendimethalin applied early postemergence. Average corn yields in herbicide-treated areas in Nebraska were 2980 kg ha-1 higher than those recorded in the untreated control.

Growth and development of three wild-proso millet biotypes (Cambridge, LeSueur, and Morris) and one cultivated proso millet (‘Crown’) were compared under noncompetitive conditions in field studies. LeSueur and Cambridge were taller than Crown and Morris at maturity. All wild types had greater leaf area and dry weight at maturity than Crown. Crown headed earlier than the wild types, and among the wild types, Cambridge was slowest to mature. Seed production was 1.4 to 2 times greater for wild than cultivated proso millet, and averaged 48 000, 69 000, 83 000, and 94 000 seeds/plant for Crown, Cambridge, LeSueur, and Morris, respectively. Mean seed weight was 4.0 and 3.8 mg/seed for LeSueur and Morris, respectively, and 5.8 and 5.9 mg/seed for Crown and Cambridge, respectively. LeSueur and Morris seed shattered readily, but Cambridge seed shattered relatively little. Seed dormancy was greater in LeSueur and Morris than in Cambridge. Based on reproductive potential, shattering, and dormancy characteristics, LeSueur and Morris appeared to have more weedy characteristics than Cambridge.

Selective postemergence herbicides were applied broadcast to control wild-proso millet in soybeans early postemergence (early post), postemergence (post), and late postemergence (late post) when wild-proso millet was 2 to 8 cm tall, 3 to 15 cm tall, and 3 to 31 cm tall, respectively. CGA-82725, fluazifop, haloxyfop, and sethoxydim applied early post controlled 75% or less late-season wild-proso millet. Interrow cultivation following early post fluazifop applications improved wild-proso millet control and soybean yields. Higher rates of CGA-82725, haloxyfop, and sethoxydim applied post controlled 91 to 98% late-season millet, but resulting soybean yields were less than the hand-weeded check. Fenoxaprop, fluazifop, fluazifop-P, haloxyfop, quizalofop, and sethoxydim applied late post provided 93 to 99% late-season millet control and soybean yields equal to hand-weeded checks. Wild-proso millet emerging after early post or post herbicide applications contributed to reduced effectiveness from those treatments. However, most wild-proso millet emerged before late post applications and were controlled. Other herbicides including BAS-51702, clethodim, cloproxydim, and SC-1084 applied late post also controlled wild-proso millet in soybeans.

Seedlings of proso millet usually were killed by discing and rototilling in field experiments but populations were not reduced by mowing or by compressing under tractor wheels. In greenhouse experiments, recently emerged seedlings had the greatest mortality after raking and desiccation treatments but were less affected by shoot and/or root damage. In contrast, seedlings treated several weeks after emergence suffered greater mortality from shoot damage and less from desiccation. Two weedy proso millet biotypes, black and Crown, were used in the field experiments, and up to six biotypes were used in the greenhouse. Few significant differences among biotypes were found. Young (emerging) seedlings were extremely resilient to all treatments.

Field studies evaluated the effects of crop, crop rotation, planting date, row spacing, no-till planting, and herbicides on wild-proso millet control. Benefin and EPTC reduced wild-proso millet biomass in new seedings of alfalfa, and the combination of herbicides and forage harvest prevented wild-proso millet seed production in that crop. Wild-proso millet seedling populations were reduced and corn yields increased when corn followed 1 to 4 yr of alfalfa. Apparent effectiveness of herbicides in corn increased after cropping with alfalfa. Germination of buried wild-proso millet seed decreased approximately 90% after 54 months which is equivalent to 4-yr prior cropping to alfalfa. Wild-proso millet control and field and sweet corn yields increased when the crops were planted late season (May 17) rather than early season (April 27). Planting sweet corn in rows spaced 76 cm rather than 108 cm apart also increased sweet corn yields. EPTC plus dichlormid (EPTC+) plus cyanazine always controlled wild-proso millet equal to or better than EPTC+ alone. When field corn was planted no-till into killed alfalfa sod, combinations of pendimethalin plus simazine and pendimethalin plus cyanazine provided the best wild-proso millet control and corn yields. But the following year when corn was no-till planted into corn stubble of the identical plots, wild-proso millet control from the same treatments tended to be lower and corn yields were reduced.

The effects of seed depth on growing point location of wild-proso millet, effects of alachlor placement, and chemical control of wild-proso millet were studied in field and greenhouse experiments. In 1986, 55 to 88% of the seedlings originating in the top 6 cm of soil had their growing point above the soil surface. The respective figures were 11 to 36% in 1987. Shoot exposure to alachlor resulted in significantly greater phytotoxicity than root exposure. Only EPTC or vernolate with a protectant, preplant incorporated, or pendimethalin preemergence, followed by atrazine plus tridiphane postemergence controlled wild-proso millet more than 85% all season.

Several weedy biotypes of wild-proso millet occur throughout Ontario. Field and laboratory studies were conducted in 1986 and 1987 to evaluate imazethapyr for preemergence and postemergence control of wild-proso millet. In the laboratory, imazethapyr, applied postemergence, effectively controlled weedy biotypes of wild-proso millet in the 4- to 5-leaf stage. Seedlings of black-seeded wild-proso millet were controlled at the 1- to 5-leaf stage by 50 g ai/ha of imazethapyr. Higher doses of imazethapyr were required to control later growth stages. In field studies, imazethapyr, applied preemergence or postemergence, effectively controlled black-seeded wild-proso millet, resulting in soybean yields comparable to the recommended postemergence treatment of sethoxydim.