An eradication plan is needed to counteract the increasing number of invasions by new plant species and the cost of resulting control programs. An eradication plan includes early detection of new species, assessment of the invader's noxious potential, surveys, understanding of the invader's biology, and technology incorporated into a strategy to eliminate the species and to revegetate invasion sites. Early detection increases the probability of successfully eradicating invading plants. Key factors in determining a plant's noxious potential are similarities among the climates of the invaded area and endemic population, the plant's history of spread, and its ability to germinate. Surveys are necessary to detect new species and to assess their threat. Reliable surveys depend on using proper methods and tactics. Population dynamics indicate the stage of a plant's life cycle most vulnerable to eradication treatments, the time to deplete viable propagules from the soil, and the strategy to stop spread. Eradication technology is based on a plant's population dynamics and must eliminate every plant from an infestation. The survey data, population dynamics, and eradication technology are combined into an eradication strategy that must stop spread, prevent reproduction, and deplete viable propagules from the soil. An effective eradication strategy specifies where and when to apply treatments, quarantine measures, criteria to assess progress, steps to prevent further invasions, and cost appraisals.

Oil-water emulsion stability was determined for crop origin and refinement of seed oils and their methyl esterified fatty acids (methylated seed oil) as influenced by emulsifiers and herbicides. Oil-in-water emulsion stability of one-refined, degummed, and crude seed oils was affected by the emulsifier. However, emulsion stability of methylated seed oil was not affected by the refinement of the seed oil used to produce the methylated seed oil or by the emulsifier. Oils without emulsifiers or emulsifiers alone added to formulated herbicide-water emulsions reduced emulsion stability depending upon the herbicide and emulsifier. Further, emulsion stability of formulated herbicides plus oil adjuvants was influenced by the oil type, the emulsifier in the oil adjuvant, and the herbicide. Oil-in-water emulsions improved or were not affected by increasing concentration of the emulsifier in the oil. However, T-Mulz-VO at a concentration greater than 10% with soybean oil or 5% with methylated soybean oil reduced emulsion stability with sethoxydim. Emulsion stability of herbicides with adjuvants depends upon the herbicide, the emulsifier, emulsifier concentration, and the crop origin, type, and refinement of oil.

Greenhouse experiments were conducted to determine ‘Len’ hard red spring wheat response to triallate and chlorsulfuron applied separately and together. Chlorsulfuron at 12 or 23 g/ha plus preplant incorporated (PPI) triallate at 1120 g/ha antagonized triallate toxicity to wheat. Chlorsulfuron reduced triallate injury to wheat less when applied preemergence (PRE) after PPI triallate compared to both herbicides applied PPI. Soaking wheat seeds in 21 and 31 ppbw chlorsulfuron solutions for 24 h before placing into triallate-treated soil did not reduce triallate injury to wheat. Applying chlorsulfuron to triallate did not reduce triallate toxicity to wild oats.

A survey to determine the frequency and weed control impact of enhanced degradation of butylate or EPTC in field soils receiving repeat applications of these herbicides was conducted in a sugarbeet and three corn growing areas of Nebraska. All seven of the sugarbeet field soils exhibited enhanced EPTC degradation. In the corn areas, none of the 13 north central and southeast field soils displayed accelerated degradation; however, 10 of the 16 south central field soils did. In south central Nebraska, 60% and 45% of the surveyed growers were dissatisfied with weed control from butylate or EPTC in 1983 and 1984, respectively, compared to 24% and none in other survey areas. Enhanced herbicide degradation and the presence of shattercane were the main reasons for the disparity among areas.

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.

Seasonal variations in tolerance of jack pine and white spruce to glyphosate and triclopyr were investigated in field and growthroom studies. Foliar injury was higher in both species following field applications of herbicides in July during periods of active growth than in September and October when the plants were not growing actively. Herbicides applied to trees in the growthroom 3 weeks after bud break caused greater injury than applications either before or 14 weeks after bud break. White spruce tolerated both glyphosate and triclopyr better than jack pine. Triclopyr injured both species more than glyphosate. Chemical analysis and electron micrographs showed that the cuticular wax deposition on both species was greater in field-grown trees than in growthroom-grown trees and was greater at 14 weeks after bud break than at 3 weeks. Increased wax deposition with time after bud break may reduce herbicide uptake and may account partially for the increased tolerance of both species to glyphosate and triclopyr.

Field experiments were conducted in 1982 through 1986 to evaluate the effect of six postemergence grass herbicides, clethodim, the methyl ester of diclofop, the butyl ester of fluazifop-P, the methyl ester of haloxyfop, the methyl ester of quizalofop, and sethoxydim, on 31 seedling grass species. All herbicides except diclofop controlled most of the species tested. None of the herbicides controlled rattail fescue or red fescue. Only clethodim and haloxyfop controlled annual bluegrass.

A decision criterion is presented for postemergence johnsongrass control in soybeans. Models derived from actual data describing the relationship between johnsongrass density (X) and soybean yield loss are used to develop the decision criterion for soybeans planted in 0.25- and 1-m row spacings. The yield loss equations are L1 = 424–424 exp (-0.023X2) for 0.25-m row spacing and L2 = 643-643 exp (−0.004X2) for 1-m row spacing. When combined with the cost of control (Px) and the expected price of soybeans (Py), these equations can be used to find the density thresholds where johnsongrass control becomes profitable. For the 0.25-m row spacing, this relationship was Px = Py [424–424 exp (−0.023X2) or more simply Px = Py L1, which equates the cost of control to the value of the soybean yield increase from control. The johnsongrass density (X) that satisfies this equality is the threshold (X*) above which control is profitable.

When centipedegrass was unmowed, seedhead suppression generally was better with imazethapyr than with mefluidide either alone or with flurprimidol, but these treatments were not effective for 8 weeks. In several instances, imazethapyr at 0.30 kg ai/ha and MH at 2.2 and 4.5 kg ai/ha severely injured (>30%) centipedegrass. Mowing weekly did not control seedhead development effectively, and none of the plant growth regulator plus mowing treatments effectively suppressed seedheads for 12 weeks. To effectively suppress seedhead production for 8 weeks, centipedegrass treated with mefluidide required mowing 3 weeks after treatment, while centipedegrass treated with imazethapyr or flurprimidol plus mefluidide required mowing at 3 and 6 weeks.

Mefluidide, Mon 4620, paclobutrazol plus mefluidide, and flurprimidol plus mefluidide temporarily injured and discolored tall fescue without reducing shoot density. Mefluidide at 0.43 kg ai/ha and Mon 4620 at 2.8 kg ai/ha suppressed vegetative growth of mowed grass 4 weeks while unmowed grass was suppressed for 8 weeks. Mefluidide at 0.14 kg/ha with either flurprimidol at 1.1 kg ai/ha or paclobutrazol at 1.1 kg ai/ha suppressed vegetative growth of mowed tall fescue for 5 and 6 weeks, respectively. Combination treatments also suppressed the growth of nonmowed tall fescue 8 to 10 weeks. Mowing effectively suppressed seedheads for 12 weeks when the grass was mowed at 3 and 6 weeks, while mowing only once at 4 weeks did not. Seedhead suppression was not improved with weekly mowing compared with two mowings. Mowing influenced the performance of plant growth regulators on vegetative growth and seedhead control but not plant injury, quality, or shoot density.

Experimental adjuvants were tested to maximize herbicidal activity of sethoxydim on quackgrass and of bentazon on common lambsquarters. Efficacious adjuvants were identified by measuring the 14C-herbicide droplet spread and absorption, as influenced by various adjuvants, on the target weed. The absorption and droplet spreadability of sethoxydim and bentazon on quackgrass and common lambsquarters leaves were increased or were decreased depending on the type of adjuvant used. No correlation was found between sethoxydim droplet spread and absorption on quackgrass. With bentazon, the relationship between these two factors was greater. Thus, measurement of droplet spread, as affected by adjuvants, was useful only as a screening technique for bentazon. Blending surfactants with paraffinic oil or soybean oil to form a crop oil concentrate changed the efficacy of the surfactant compared to the surfactant by itself. Surfactants most effective as components of paraffinic-oil based crop oil concentrate were different from surfactants ideal for inclusion with soybean oil-based crop oil concentrate. Thus, the effectiveness of a crop oil concentrate depends on herbicide, surfactant, and oil types. In the field, several of the superior adjuvants identified in the laboratory enhanced sethoxydim and bentazon activity on grass and broadleaf weeds.

Soft red winter wheat cultivars were evaluated in field experiments in Georgia for tolerance to dicamba alone and mixed with 2,4-D. Treatments reduced ‘Florida 302’ yield more than ‘Florida 301’ or ‘Coker 983’ at Tifton in 1986. Mid-tillering Florida 302 wheat was more sensitive to treatment than fully tillered wheat. In 1987, dicamba plus 2,4-D applied at mid-tillering reduced yields of all cultivars in Watkinsville. Injury and yield reductions occurred primarily when mid-tiller treatments were applied to wheat that was planted 10 or 21 days later than recommended at Tifton or Watkinsville, respectively. When applied according to labeling, dicamba or dicamba plus 2,4-D use in Georgia soft red winter wheat can reduce grain yield.

Interstate rights-of-way may serve as weed host reservoirs for the tarnished plant bug, an insect pest of cotton. Management of these rights-of-way may have an impact upon cotton pest management. In a 3-yr study, time of mowing, frequency of mowing, and sulfometuron methyl applied against overwintering rosettes influenced the cover of annual fleabane and wild carrot, which harbor tarnished plant bugs.

The purpose of the research was to determine the effect of several postemergence herbicides on transpiration and growth of seedling oats and wheat. Fluazifop, haloxyfop, and sethoxydim were applied postemergence at various rates to oats and wheat in the 1- to 2-leaf stage in controlled environment rooms and the field. In all cases where transpiration was reduced significantly, oats were affected more than wheat. Generally, haloxyfop and sethoxydim in both controlled environments and the field suppressed oat growth more than wheat. Fluazifop controlled both small grain species equally in the field, but oats were suppressed more under controlled environment conditions. Effects of the three herbicides were always greater in the controlled environments than in the field.

Field studies were conducted for 3 yr to evaluate the persistence of metolachlor and alachlor applied to ‘Centennial’ soybean and to determine their residual effect on ‘Mars' rice. At labeled use rates of metolachlor at 2.8 kg ai/ha and alachlor at 3.9 kg ai/ha, soil residue levels in the fall 5 months after application on Crowley and Midland silt loam soils averaged 0.04 and 0.05 ppmw, respectively. Metolachlor fall soil residues averaged 3.5 times higher when applied at 5.6 and 11.2 kg/ha compared to 2.8 kg/ha, but residues for labeled and double rates of alachlor were similar. In the spring 9 months after herbicide application, soil residues averaged over years did not exceed 0.06 ppmw. The 3-yr rice yields were not affected by residual metolachlor or alachlor.

Johnsongrass control in the field was greater with fenoxaprop or haloxyfop than with sethoxydim in 1985 and 1986. Johnsongrass control was reduced under field and greenhouse conditions by adding a dimethylamine salt of 2,4-D. Generally, the antagonism was overcome by increasing the rate of fenoxaprop, haloxyfop, or sethoxydim. Sethoxydim showed less antagonism from 2,4-D than did fenoxaprop or haloxyfop in the greenhouse.

Several labeled herbicide treatments reduced winter wheat height and grain yield when applied at different growth stages in 1984 and 1985. Yield reductions were related to reduced spike production. Wheat height and yield generally were greatest when herbicides were applied at Zadoks' Stage 29 and lowest at Stage 13. Herbicide treatments did not affect wheat kernels per spike, kernel weight, volume weight, or germination either year. However, most herbicide treatments either increased or decreased seed protein content, depending on the year.

Imazaquin and imazethapyr were applied postemergence to soybeans for control of 8- to 12-leaf rhizome johnsongrass and pitted morningglory in the field. At 8 weeks, johnsongrass control was 70% with 70 g ai/ha imazaquin plus 105 g ai/ha imazethapyr but was no more than 50% with a single application of either herbicide. Imazaquin at 70 g/ha plus imazethapyr at 35 g/ha interacted synergistically to provide 90% pitted morningglory control, while 140 g/ha imazaquin controlled 77%. Imazaquin at 70 g/ha with imazethapyr from 18 to 105 g/ha controlled both weed species equal to or better than that obtained with 140 g/ha imazaquin.

The effect of glyphosate applied as a desiccant to field bindweed-infested alfalfa in the final year of seed production was examined in field experiments near Lovelock, NV. Glyphosate at 2.5 and 5.0 kg ae/ha flat fan applied was equal to and/or superior to dinoseb for desiccation of foliage, respectively. Alfalfa seed yield and quality following glyphosate treatment were similar to that of dinoseb-treated alfalfa. Glyphosate treatment reduced some alfalfa and field bindweed stands. A beneficial interaction between low-volume control droplet application (CDA) and glyphosate was not evident.