Field studies were conducted in 1994 and 1995 to determine the contribution of PRE applications of alachlor, metolachlor, acetochlor, SAN 582H, or pendimethalin on woolly cupgrass and wild-proso millet control when followed by POST nicosulfuron at 0, 0.018, 0.027, or 0.036 kg ai/ha. Sequential treatments controlled woolly cupgrass and wild-proso millet greater than single applications of PRE herbicides, which when applied alone resulted in the least wild-proso millet control and lowest corn grain yield. Lack of complete woolly cupgrass control with POST nicosulfuron alone resulted in corn grain yield that was less than with sequential treatments but was equal to PRE treatments. Wild-proso millet control with nicosulfuron at 0.027 kg/ha resulted in corn grain yield that was less than with sequential treatments, but greater than with all PRE treatments except for SAN 582H. All PRE herbicides, regardless of early season performance, when followed by nicosulfuron resulted in woolly cupgrass and wild-proso millet control that was similar. Woolly cupgrass seed production compared to the nontreated check was reduced 98% with acetochlor followed by nicosulfuron. Sequential treatments provided the most consistent woolly cupgrass and wild-proso millet control, the highest corn grain yield, and the greatest reduction in woolly cupgrass and wild-proso millet seed production.

A field study was conducted in 1994 and 1995 to determine the effect of MON 12037, linuron, and ametryn on purple nutsedge density in field corn in a 2-yr rotation with cotton. Each corn treatment included cultivation and noncultivation. A standard treatment for purple nutsedge control was applied to all cotton plots in the second season of the corn–cotton rotation. Purple nutsedge shoot densities were reduced in cultivated MON 12037, noncultivated MON 12037, and cultivated ametryn in the corn–corn and corn–cotton rotations. Purple nutsedge tuber population was reduced in the corn–corn rotation by MON 12037 with and without cultivation, cultivated linuron, and cultivated ametryn treatments relative to the noncultivated check. In the corn–cotton rotation, purple nutsedge tuber population was reduced only by the cultivated MON 12037 and cultivated ametryn treatments relative to the noncultivated check.

The effects of herbicide–adjuvant combinations and times of application on weed density and corn yield were determined in a 3-yr field study. At a given rate and time of application of bentazon/atrazine, Assist and Merge were equally effective adjuvants. Assist would be the adjuvant of choice for bentazon/atrazine rather than Merge because of its currently lower cost. Weed density depended on the rate and time of application of bentazon/atrazine. In general, bentazon/atrazine applied at early stages (7 d after emergence) of the development of corn seedlings or at high or intermediate rate (1.6 or 0.8 kg ai/ha) maintained low weed densities, with a relatively small range of variation over years. Delay in time (14 or 21 d after emergence) or reduction in herbicide rate (0.4 kg ai/ha) increased the risk of high weed pressure, although it was not always associated with yield loss. The best time for the application of postemergence herbicide appears to be a few days prior to the onset of the critical period of weed control.

Component yields and forage quality were evaluated in established stands of alfalfa seeded alone and in binary mixtures with smooth bromegrass, orchardgrass, or timothy. Forage yields and quality were determined at three annual harvests in the third and fourth years after seeding. Weed yields in alfalfa seeded alone were significantly greater than those in the alfalfa–orchardgrass mixture. Average weed content was 24, 17, 2, and 15% for the alfalfa seeded alone, alfalfa–bromegrass, alfalfa–orchardgrass, and alfalfa–timothy, respectively. Seeding alfalfa with orchardgrass increased first harvest and annual forage yields while reducing alfalfa yield. Yields of orchardgrass often exceeded those of bromegrass or timothy. In the first harvest each year, crude protein was reduced and acid detergent fiber and neutral detergent fiber increased by including orchardgrass. Neutral detergent fiber was greater in alfalfa–orchardgrass than in the alfalfa seeded alone at most harvests. There were no consistent differences among the alfalfa seeded alone and the other mixtures in yield or quality.

Shredded newspaper (2.5, 7.6, 12.7, and 17.8 cm depth), chopped newspaper (2.5 and 7.6 cm), wheat straw (15.2 cm), black plastic, and plastic landscape fabric were evaluated during 1993 and 1994 in West Virginia for their effect on soil temperature, soil moisture, weed control, and yield in tomato. Shredded newspaper and wheat straw applied at 0, 2, 4, or 6 weeks after transplanting (WAT) and napropamide (2.1 kg ai/ha) plus metribuzin (0.28 kg ai/ha) applied at transplanting were evaluated during 1992 and 1993 in North Carolina for effect on weed control and tomato yield. Results from West Virginia indicated that shredded (7.6 cm) and chopped (7.6 cm) newspaper conserved moisture similar to higher application rates of the shredded material. Higher newspaper mulching rates reduced soil temperature compared to black plastic and bare ground. Chopped newspaper controlled weeds more consistently than other treatments. At least 7.6 cm of chopped newspaper mulch was required to control weeds at least 90%. Wheat straw was not as effective in controlling weeds as 7.6 cm or greater of newspaper mulch. Chopped newspaper provided higher tomato yields than shredded newspaper applied at the same rates. Mulches applied at 0, 2, or 4 WAT resulted in weed control similar to the chemical treatment. In North Carolina, mulches applied 2 or 4 WAT resulted in tomato yields similar to the chemical treatment. Shredded and chopped newspaper have potential as a mulching material but may vary in effect in different environments and vegetable crops.

POST herbicides were applied at four soybean growth stages to evaluate their effect on triazine-resistant (TR) kochia in 1991, 1992, and 1993. Applying imazethapyr at 70 g ai/ha or bentazon plus imazethapyr at 1,120 plus 70 g ai/ha controlled 75 to 100% of 1- to 13-cm-tall TR kochia consistently across growth stages and years. Acifluorfen at 560 g ai/ha, chlorimuron at 13 g ai/ha, or chlorimuron plus thifensulfuron at 4 plus 4 g ai/ha controlled 68 to 96% of 1- to 2-cm-tall TR kochia at soybean growth stage VC to V1, and control was inconsistent at later growth stages. In most instances, soybean seed yield was greater with herbicides applied at the V1 or V2 growth stage of soybean compared with the V4 and V5 growth stage because of better weed control. No wheat yield reduction occurred because of herbicide carryover in 1992 and 1994. However, in 1993, imazethapyr and bentazon plus imazethapyr treatments applied in 1992 caused 22% injury and reduced winter wheat yield 10% when wheat was planted after soybean harvest.

Researchers are currently developing predictive weed management models to aid producers in maintaining or improving economic profitability of peanut production while minimizing herbicide inputs and reducing environmental impact. HERB (Version 2.1.P), a computer decision model, has recently been developed for peanut and is now awaiting validation of weed control decisions before being released to the public. Field validation trials in 1994 and 1995 indicate that the current competitive index parameters in the HERB model are invalid, and statistically estimated competitive indices were generated. Estimating new parameters improved R2 values from 0.37 to 0.61. New competitive index parameters allow the HERB model to more accurately predict the level of yield loss at a given weed density.

Thiazopyr at 0.14, 0.28, and 0.42 kg ai/ha and pendimethalin at 1.1 kg ai/ha applied preemergence (PRE) were compared as components in weed management systems for no-till cotton. Mid- and late-season control of mixtures of large crabgrass, goosegrass, and fall panicum by thiazopyr at 0.28 kg/ha was 89 to 97% and 11 to 50%, respectively, compared with 11 to 38% midseason and 0 to 5% late-season control by pendimethalin. Thiazopyr at 0.42 kg/ha and pendimethalin controlled broadleaf signalgrass 44 and 0%, respectively, late in the season. Adding fluometuron PRE at 1.7 kg ai/ha had little to no effect on large crabgrass, goosegrass, and fall panicum control but increased broadleaf signalgrass control 47 to 79 percentage points compared with thiazopyr or pendimethalin alone. Late-season control of annual grasses by thiazopyr or pendimethalin plus fluometuron PRE followed by methazole plus MSMA early postemergence (POST)-directed and cyanazine plus MSMA late POST-directed was at least 95% at two locations and 80% at the third location. Common lambsquarters was controlled 54 and 95% in systems without and with fluometuron PRE, respectively. Acceptable control of ivyleaf, pitted, and tall morningglories at all locations and smooth pigweed at two of three locations was achieved only in systems with POST-directed herbicides. Adding POST-directed herbicides to systems with thiazopyr or pendimethalin plus fluometuron PRE increased cotton yield at two of three locations. Treatments had no effect on fiber quality.

The effect of annual defoliation on leafy spurge-infested rangeland was investigated over a 5-yr period. Artificial defoliation was conducted once or twice annually at various phenological growth stages of leafy spurge to simulate grazing by herded Angora goats. Single defoliation treatments did not reduce total leafy spurge stem densities. Defoliation twice in a growing season for 4 consecutive yr reduced total leafy spurge stem densities by 55% over nondefoliated controls. Grass foliar cover and yield increased in all defoliation treatments. Despite the increased grass yield on single defoliation treatments, cattle use would likely be limited in these treatments due to the high density of leafy spurge stems. Stem densities of leafy spurge in twice-defoliated treatments should not deter cattle from grazing these sites, thereby increasing the available forage supply. The data suggest that repeated grazing of leafy spurge-infested rangeland within a growing season would be required to reduce stem densities adequately and increase cattle use and production from these sites.

Rates and application timings of postemergence herbicides for wild oat control in spring wheat and barley were evaluated at Crookston, MN, from 1994 to 1996. Diclofop, imazamethabenz, and fenoxaprop plus MCPA plus thifensulfuron plus tribenuron were applied to one- to three-leaf wild oat; and difenzoquat, imazamethabenz, fenoxaprop plus MCPA plus thifensulfuron plus tribenuron, and fenoxaprop plus 2,4-D plus MCPA were applied to four- to five-leaf wild oat at 1/2 ×, 3/4 ×, and 1 × rates. Wild oat response to herbicide rate and timing was similar in wheat and barley. Wild oat control with 1/2 × rates generally was less than that with 3/4 × rates, which was lower than or similar to that with 1 × rates. Wild oat biomass was often reduced less with 1/2 × rates than 1 × rates. However, reducing herbicide rates generally did not influence grain yields or net economic return. Grain yields and net economic return were generally greater in herbicide-treated plots than in the nontreated control.

This research was designed to determine if sethoxydim-resistant corn hybrids exhibited levels of cross-resistance to other acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides. Three sethoxydim-resistant hybrids were tested in 1995 and four in 1996. The hybrids were treated with the 1 × (labeled use rate for annual grass control) and 4 × rate of clethodim, fenoxaprop-P plus fluazifop-P, fluazifop-P, quizalofop-P, and sethoxydim. At the 1 × rate, similar levels of corn safety were observed in both years with sethoxydim, quizalofop-P (except Asgrow RX620SR in 1995), and in 1996, fenoxaprop-P plus fluazifop-P. Corn treated with the 4 × rate of sethoxydim did not exhibit injury, while all other ACCase-inhibiting herbicides cause > 50% corn injury. Sethoxydim-resistant com hybrids used in this study did not consistently exhibit acceptable levels of cross-resistance to other ACCase-inhibiting herbicides. The use of clethodim will control volunteer sethoxydim-resistant corn in rotational crops.

Optimal application timing for dicamba–acetamide tank mixes was examined in field studies conducted in Michigan and Wisconsin from 1993 to 1995. Dicamba was tank mixed with alachlor, metolachlor, or SAN 582H and applied at planting, 7 d after planting, and 14 d after planting. Additional dicamba plus alachlor tank mixes applied at all three timings were followed by nicosulfuron postemergence to determine the effects of noncontrolled grass weeds on corn yield. Delaying application of dicamba–acetamide tank mixes until 14 d after planting often resulted in lower and less consistent giant foxtail control compared with applications at planting or 7 d after planting. Corn grain yield was reduced at one site where giant foxtail control was lower when application was delayed until 14 d after planting. Common lambsquarters control was excellent with 7 or 14 d after planting applications. At one site, common lambsquarters control and corn yield was reduced by application at planting. Dicamba–alachlor tank mixes applied 7 d after planting provided similar weed control or corn yield, while at planting and 14 d after planting applications provided less consistent weed control or corn yield than a sequential alachlor plus dicamba treatment or an atrazine-based program.

Feral rye and jointed goatgrass are winter annual grasses that infest winter wheat in the western United States. Currently, no herbicides are available that selectively control these weeds in wheat. Because of this constraint, producers need cultural practices that reduce the seed densities of these two grasses in the soil seedbank. This research shows that applying nitrogen 5 mo before wheat planting and increasing the seeding rate with a tall wheat cultivar reduces seed production per plant of either species by > 40%. However, tall wheat cultivars usually yield less grain than semidwarf cultivars. Producers can avoid this yield loss by combining narrow rows with time of N application and increased seeding rate of semidwarf cultivars. This combination reduces weed seed production similarly to cultural systems with tall cultivars.

A small -plot, pneumatic applicator was developed to apply either granular herbicide formulations or liquid herbicides impregnated on commercial dry fertilizer to field research plots. Pre-weighed herbicide samples poured into a stainless steel, motor-driven belt, cone seeder are automatically sput into four subsamples in a four-outlet rota seed distributor run by a 12-volt electric motor, and delivered to four plastic venturi chambers. A gasoline engine-powered leaf blower forces air through a 10-cm diam polyvinylchloride (PVC) pipe to the input sides of the venturi chambers. The forced air stream carries the herbicide samples through 2.5-cm diam flexible plastic tubing to four deflector shields mounted 61 cm apart on a fiberglass boom. The applicator uniformly delivers granules up to 400 kg/ha in a 2.5-m wide swath.

This paper describes the design, construction, and operation of tilted beds to investigate the effectiveness of vegetative filter strips (VFS) in removing agricultural chemicals from runoff water. The beds are designed to catch surface runoff, leachate, and subsurface lateral flow. Switchgrass was established on beds filled with Cullen clay loam or Emporia sandy loam. Switchgrass establi shed on Cullen clay loam beds reduced surface runoff by 60% and by 11% in sandy loam containing switchgrass compared to respective bare soils. Infiltration was 64, 26, 17, and 8% for clay loam with switchgrass, clay loam without switchgrass, sandy loam with switchgrass, and sandy loam without switchgrass, respectively.

SAN 582 at 1.1, 1.2, 1.3, 1.5, and 1.6 kg ai/ha; alachlor at 1.7, 2.2, and 2.8 kg/ha; and metolachlor at 1.7, 2.2, and 2.8 kg/ha were applied preemergence without and with atrazine at 1.7 kg/ha in no-till corn at two locations near Blacksburg, VA, in 1993 and 1994. SAN 582, alachlor, and metolachlor controlled TR-smooth pigweed when applied without or with atrazine, and with only a few exceptions, control was greater than 60%. The highest rate of individual herbicides was more effective than the lowest rate in most cases. Early control of TR-smooth pigweed was similar from all three herbicides, especially at higher rates, but control later in the season tended to be best with alachlor. As expected, atrazine applied alone did not control TR-smooth pigweed, and crop yields were increased with herbicide treatments compared to no treatment.

The English daisy, Bellis perennis L., is a widespread lawn weed and a bane to those who favor daisy-free lawns and golf courses. The genetic name Bellis, a designation used by Pliny, means “pretty”; perennis means “through the years,” “continuing,” or “perennial” (Gledhill 1985; Mabberley 1989). While pretty, the English daisy is a persistent weed that spreads by short stolons (Tutin et al. 1976). It is a member of the cosmopolitan family Compositae, which encompasses 1,100 genera and 25,000 species (Heywood 1993). The genus Bellis comprises about 15 European and Mediterranean species. Some of them are medicinal and some are cultivated ornamentals, especially forms of B. perennis. The signature of this species is a flower head that Closes at night and in wet weather (Tutin et al. 1976).

My remarks today will be largely devoted to assessing some of the effects of the Food Quality Protection Act of 1996. As introduced, the act had wide support among grower groups, the food industry, and the pesticide industry. Voting on the bill was unanimous in both House and Senate, and action was completed in 1 wk. The legislation was signed by the President on August 3, 1996. President Clinton wanted to be seen as a strong advocate of children's health. The Republican Congress wanted to show that it was pro-environment.