Effects of linuron on annual bluegrass control and Kentucky bluegrass cultivar tolerance were studied in field and growth chamber experiments. In controlled environment experiments, linuron at 0.06, 0.12, 0.25, 0.50, and 0.75 kg ai ha-1 was applied to pure stands of annual bluegrass and eight Kentucky bluegrass cultivars. Linuron at the two highest rates controlled annual bluegrass, reducing the clipping dry weight by more than 85% 4 wk after treatment, and by 65 to 92% 6 wk after treatment. Growth of Kentucky bluegrass was reduced with the most severe reduction occurring 2 wk after linuron application. All cultivars exhibited normal growth 8 wk after treatment. In field experiments, linuron at rates from 1.5 to 2.0 kg ai ha-1 controlled annual bluegrass in old (> 5 yr) Kentucky bluegrass stands, and in 16 cultivars of 1-yr and 2-yr-old Kentucky bluegrass stands, with little or no damage. At rates of 1.5, 2.0, and 2.5 kg ai ha-1 linuron, damage to newly seeded cultivars was moderate to severe. However, 6 to 7 wk after linuron application to newly seeded cultivars, stand density and turf quality were equivalent to untreated checks.

Sixty isolates of the plant pathogenic fungus Sclerotinia sclerotiorum (Lib.) de Bary and six isolates of Sclerotinia minor Jagger were evaluated in a controlled environment for virulence on leaves excised from 8-week-old dandelion plants. Significant negative correlations were obtained between the relative virulence of the isolates and the dry weights of dandelion plants inoculated in a controlled environment; and positive correlations were detected between the relative virulence of isolates and reduction in number of dandelion plants in turfgrass swards infested with inoculum of the isolates. In August 1988, an 80.7% reduction in the number of dandelion plants was detected in a turfgrass sward treated in 1987 with four applications of heat-killed seed of perennial ryegrass (100 g m−2 application–1) infested with isolate R30 of S. sclerotiorum, followed by six applications at the same rate in 1988. Populations of dandelions in untreated swards increased by 22.2% during the same period. Heat-killed seed of perennial ryegrass (100 g m−2) infested with isolate R30 applied simultaneously with dandelion seed (25 g m−2) onto a sward of Kentucky bluegrass reduced the establishment of dandelion seedlings by 85.5%. Necrosis or discoloration did not develop on Kentucky bluegrass, creeping bentgrass, annual bluegrass, or quackgrass treated with inoculum of Sclerotinia. Sclerotia of Sclerotinia spp. were found, on occasion, in crowns but not on the foliage of diseased dandelions.

Turf managers use prodiamine to control annual grasses in mature turfs. Earlier, evaluations of prodiamine have indicated it has an elevated soil persistence and high activity on susceptible species. This persistence raises concern for prodiamine's effect on juvenile turf. An experiment was established to evaluate the effect of prodiamine on juvenile Kentucky bluegrass turf. Significant loss of quality occurred on turf less than one year old receiving a single application of prodiamine at ≥ 1.4 kg/ha. Split applications of prodiamine did not significantly decrease turf quality. Prodiamine at 0.8 and 2.2 kg ai/ha and DCPA at 23.5 kg ai/ha, applied in the fall the previous three years, significantly reduced the number of overseeded Kentucky bluegrass seedlings two years after planting. In a subsequent study, prodiamine at ≥ 0.8 kg/ha and DCPA at 23.5 kg/ha applied once the previous fall significantly reduced the number of overseeded Kentucky bluegrass dlings 56 d after planting. An analysis of prodiamine rate versus seedling density was found to be significantly correlated (r2 = 0.79).

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.

Seedlings from golden delicious apples (Malus domestica Borkh. ‘Smoothee’) were grown in the greenhouse with orchardgrass (Dactylis glomerata L. # DACGL), Kentucky bluegrass (Poa pratensis L. # POAPR), red sorrel (Rumex acetosella L. # RUMAA), and Korean lespedeza (Lespedeza stipulacea L. # LESSL) at four densities and four fertility levels. Orchardgrass and red sorrel inhibited tree growth more than Kentucky bluegrass on a per plant basis. Korean lespedeza inhibition of apple growth was associated with the amount of root nodulation on the Korean lespedeza. Apple shoot dry weight over all fertility levels, ground cover species, and densities was predicted by a regression model based on increase with fertility and decrease with ground cover dry weight. These results indicate that the competitiveness between equal number of ground cover species is due to differences in biomass production. Addition of nitrogen to the system increased nitrogen levels in apples but did not completely overcome apple growth inhibition.

Five perennial cool-season grasses: Kentucky bluegrass, creeping red fescue, tall fescue, orchardgrass, and perennial ryegrass were treated at the 2- to 3-leaf, 3- to 4-leaf, 4- to 6-leaf, and 6- to 7-leaf growth stages with four rates (0, 0.14, 0.28, and 0.56 kg ai/ha) of the butyl ester of fluazifop. Creeping red fescue was not injured by any rate at any growth stage. Reduction in shoot dry weight increased linearly with increasing fluazifop rate for the remaining four species, except for the 6- to 7-leaf stage in Kentucky bluegrass and the 4- to 6-leaf stage in tall fescue and perennial ryegrass. Significant differences between growth stages within each rate varied with species. In general, tolerance increased at the 4- to 6-leaf and 6- to 7-leaf growth stages.

A weed survey of 115 Nova Scotia lowbush blueberry fields was conducted during the summers of 1984 and 1985 to determine the most common and prevalent weeds associated with blueberry production. A total of 119 weed species were observed within the surveyed blueberry fields. The most common weed species were bunchberry, colonial bentgrass, poverty oatgrass, sheep sorrel, and false lily-of-the-valley. Weeds with low relative abundance in this study, but which may become more widespread, include three-toothed cinquefoil, Kentucky bluegrass, hair fescue, canker-root, and Canadian St. Johnswort.

Hereford cows and their spring-born calves grazed an irrigated grass pasture containing about 13% dandelion based on dry weight yield. Grazing treatments were 1) no grazing, 2) 4 days of grazing just before clipping, and 3) long-term grazing just before clipping. In clippings taken in June and July after the grazing treatments, the percentage dandelion in the forage was similar in all three grazing treatments, indicating that cattle used dandelion as readily as grass. The protein and mineral contents of dandelion were at appropriate levels to meet the established requirements of beef cattle.

Postemergence applications of BAS 9052 OH, {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, at 0.25 and 0.5 kg ai/ha were made to 27 temperate and 28 tropical species of Gramineae. Annual bluegrass (Poa annua L. ♯3 POAAN) and rattail fescue (Festuca myuros L. ♯ VLPMY) were resistant to these rates of BAS 9052 OH. Five species of fescue and three species of bluegrass received postemergence applications of BAS 9052 OH at rates of 0.1 to 6.4 kg ai/ha. The germination of seeds and the subsequent growth of the seedlings of these species as influenced by various concentrations of BAS 9052 OH were also studied. Meadow fescue (Festuca pratensis Huds. ♯ FESPR), tall fescue (Festuca arundinacea Schreb. ♯ FESAR), Kentucky bluegrass (Poa pratensis L. ♯ POAPR), and rough-stalked meadowgrass (Poa trivialis L. ♯ POATR) were most susceptible; annual bluegrass was somewhat less resistant; hard fescue (Festuca longifolia Thuill) was resistant; red fescue (Festuca rubra L. ♯ FESRU) and rattail fescue were very resistant.

Kentucky bluegrass (Poa pratensis L. ‘Parade’, ‘Adelphi’, ‘Glade’, and ‘Rugby’ # POAPR) and tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’ # FESAR) were treated in field experiments with chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide}. The objectives of the two experiments were to determine if this herbicide has the potential to be used for selective control of tall fescue in Kentucky bluegrass turf. Chlorsulfuron treatments included single rates of 0, 18, 35, 71, 141, 212, and 282 g ai/ha and split rates, applied 14 days apart, of 18 + 18, 35 + 35, 71 + 71, 141 + 141, and 212 + 212 g/ha. Clipping weights and turfgrass quality ratings were taken in both experiments. Kentucky bluegrass showed a higher tolerance to the chemical, with no decrease in turf quality at the highest single and split application rates in both experiments. However, as the chlorsulfuron rate increased, clipping weight decreased. Tall fescue showed a low tolerance to the chemical and was controlled at single rates of 141 g/ha and split rates of 141 + 141 g/ha and greater. Although the tall fescue recovered from damage at single rates of 71 g/ha and split rates of 71 + 71 g/ha, severe growth inhibition and discoloration of aboveground tissue occurred at the lower rates. Twelve months after the first chlorsulfuron was applied in each experiment, glyphosate [isopropylamine salt of N-(phosphonomethyl)glycine] was sprayed over the plots to kill all existing plant material, and Kentucky bluegrass was seeded into the plots 2 weeks later at the rate of 0.75 kg/100 m2. There was no inhibition of bluegrass seed germination at any of the rates of chlorsulfuron.

Fall application of a PRE herbicide offers professional lawncare applicators additional flexibility in scheduling necessary weed control operations. A 3-yr field study was established on common Kentucky bluegrass in Urbana, IL to examine the effectiveness of fall- or spring-applied prodiamine and DCPA for spring large and smooth crabgrass control. Prodiamine was effective for crabgrass control in turf (≥ 91% control) when applied in spring at ≥ 0.4 kg/ha or when it was applied in the fall at ≥ 0.6 kg/ha (≥ 82% control). In most cases, fall-applied prodiamine at the 0.8 kg/ha rate (≥ 91% control) controlled crabgrass as well as spring-applied DCPA at the 11.8 kg/ha rate (≥ 94% control). Little reduction in turf quality (≥ 8.3) occurred when prodiamine was applied in the fall at 0.8 kg/ha or less. Only when prodiamine was applied at 2.2 kg/ha was there significant quality loss (7.3) with spring applications. In a second experiment to evaluate split fall and spring prodiamine applications for crabgrass control, all split applications had 100% crabgrass control which was not significantly different from single applications of ≥ 1.4 kg/ha.

The metabolism of the herbicide 14C-glufosinate (GA) was studied in excised shoots and leaves of 20 weed and nonweed species; GA was fed through the xylem. After 24 or 48 h of incubation, the plant material was examined for phytotoxic symptoms, analyzed by autoradiography, and extracted. The extract was cleaned up and analyzed by high-performance liquid chromatography. GA and its metabolites were identified by cochromatography with authentic 14C-labelled reference compounds. 14C-GA was rapidly absorbed by the excised plant parts. Most of the radioactivity (91.3 to 99.7%) in the shoots and leaves was extractable. The main metabolite observed with all species was 3-(hydroxymethylphosphinyl)propionic acid (MPP); lower amounts of 2-hydroxy-4-(hydroxymethylphosphinyl)butanoic acid (MHB) were also found in 14 species. Metabolic rates of GA varied considerably ranging between 13.1 and 2,836.5 ng GA h−1 mg−1 protein. The species with the highest rates of metabolism of GA were Galium verum (2,836.5 ng GA h−1 mg−1 protein), Lythrum hyssopifolia (846.0 ng GA h−1 mg−1 protein), and Digitalis purpurea (494.8 ng GA h−1 mg−1 protein). The mean value across all species was 275.9 ng GA h−1 mg−1 protein.