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- Author or Editor: P. H. Dernoeden x
Little is known about deleterious or beneficial nontarget effects of fungicides applied to turfgrasses. Five fungicides from several chemical classes were applied six times annually over 5 years to field plots of either `Regal' or `Fiesta' perennial ryegrass (Lolium perenne L.). All fungicides improved turfgrass quality during Spring 1984, Summer 1984 and 1985, Fall 1984, and Winter (except benomyl and chlorothalonil) 1985. Improved quality in Spring 1984 was attributed to red thread [Laetisaria fuciformis (McAlp.) Burds.] control; whereas, improved quality in Summer 1985 was due to brown patch (Rhizoctonia solani Kuhn.) control. For other years and seasons, the mechanism of improved quality provided by the fungicides was not determined. Other than red thread and brown patch control, few nontarget benefits and no nontarget detriments were observed visually with multiple applications of the fungicides evaluated. Chemical names used: methyl[1-butylamino carbonyl]-1H-benzimidazol-2-yl]carbamate(benomyl); tetrachloroisophthalonitrile (chlorothalonil); 1-isopropyl-carbamoyl-3-(3,5-dichlorophenyl) hydantoin (iprodione); bis(dimethyl-thio-carbamoyl) disulfide (thiram); and 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-y1)-2-butanone (triadimefon).
Fenoxaprop is used on turfgrasses to control smooth crabgrass [Digitaria ischaemum (Schreb. ex Sweib.) Schreb. ex Muhl.] and other annual grass weeds. Our objective was to determine if a broadleaf weed herbicide (BWH = 2,4-D + mecoprop + dicamba) would affect fenoxaprop activity. The BWH was applied several days or weeks before and after fenoxaprop was applied. Smooth crabgrass control by fenoxaprop was reduced significantly when the BWH was applied ≤14 days before fenoxaprop was applied. Extremely poor crabgrass control occurred when fenoxaprop was tank-mixed with the BWH. There was no reduction in crabgrass control when the BWH was applied 21 days before or ≥3 days after fenoxaprop. Chemical names used: ethyl ester of (±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid (fenoxaprop); 2,4-dichlorophenoxy acetic acid (2,4-D); (+)-2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop); 3,6-dichloro-2-methoxybenzoic acid (dicamba).
In this field study, five preemergence and two postemergence herbicides were evaluated for their ability to hasten Meyer zoysiagrass (Zoysia japonica Steud.) sod development when sod was established from the regrowth of rhizomes, sod strips, and loosened plant debris. Herbicide influence on zoysiagrass re-establishment was examined using two postharvest field preparation procedures as follows: area I was raked to remove most above-ground sod debris, whereas in adjacent area II sod debris was allowed to remain in place. Herbicides that controlled smooth crabgrass [Digitaria ischaemum (Schreb.) Muhl.] generally enhanced zoysiagrass cover by reducing weed competition. Meyer established from rhizomes, sod strips, and loosened plant debris, and treated with herbicides, had a rate of sod formation equivalent to that expected in conventionally tilled, planted, and irrigated Meyer sod fields. Effective smooth crabgrass control was achieved when the rates of most preemergence herbicides were reduced in the 2nd year. Chemical names used: dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (DCPA); 3,5,-pyridinedicarbothioic acid, 2-[difluromethyl]-4-[2-methyl-propyl]-6-(trifluoromethyl)∼S,S-dimethyl ester (dithiopyr); [±]-ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy] propanoate (fenoxaprop); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-[1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine(pendimethalin);N3,N3-di-n-propyl-2,4-dinitro-6-[trifluromethyl)-m-phenylenediamine (prodiamine); and 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac).
Various rates of ethofumesate were evaluated for annual bluegrass (Poa annua L.) control in a perennial ryegrass (Lolium perenne L.) fairway. The tolerance of ‘Merion’, ‘Mystic’, and a blend of Kentucky bluegrasses (Poa pratensis L.) to ethofumesate also was assessed. Ethofumesate at 0.84, 1.1, and 0.84 + 0.84 kg·ha–1 provided poor annual bluegrass control; 2.2 and 1.1 + 1.1 kg·ha–1 provided good control; and 2.2 + 1.1 and 2.2 + 2.2 kg·ha–1 provided excellent control. Overall quality of Kentucky bluegrass was only slightly reduced by ethofumesate at 1.1 or 2.2 kg·ha–1; however, split applications at 2.2 + 1.1 and 2.2 + 2.2 kg·ha–1 severely reduced bluegrass cover and overall quality for 7 months. Foliar growth of sequentially treated Kentucky bluegrass appeared suppressed throughout fall and winter. Between January and April, Kentucky bluegrass plots treated with split applications of 2.2 + 1.1 or 2.2 + 2.2 kg·ha–1 had a dark-green color. No visual injury was observed in perennial ryegrass. Ethofumesate applied at 2.2 or 1.1 + 1.1 kg·ha–1 provided the best combination of safety to Kentucky bluegrass and control of annual bluegrass. Chemical names used: (±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate (ethofumesate).
This study was conducted to determine if the rate of ‘Meyer’ zoysiagrass (Zoysia japonica Steud.) establishment and spread could be enhanced when plugs were introduced into plant growth regulator-(PGR) treated Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) turfs. During the first growing season, PGR treatment made little difference in zoysiagrass spread. Zoysiagrass coverage in perennial ryegrass treated with mefluidide (57%) or amidochlor (63%) was significantly greater than in ryegrass treated with ethephon (47%) or the untreated control (48%) by the end of the 2nd year. Enhanced zoysiagrass spread in perennial ryegrass treated with mefluidide and amidochlor was attributed to stand thinning resulting from PGR phytotoxicity and environmental stress in the first year. Zoysiagrass coverage in Kentucky bluegrass was greatest in mefluidide-treated plots, but the increase over the control was only 6%. Flurprimidol slowed the establishment of zoysiagrass in both cool season turfs. Chemical names used: [(N-[(acetylamino)methyl]-2-chloro-N-(2,6-diethyl phenyl)acetamide (amidochlor); (2-chloroethyl)phosphonic acid (ethephon); α-(l-methylethyl)-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); and N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide (mefluidide).
In a field test of 25 Kentucky bluegrass cultivars (Poa pratensis L.) “common types” were generally more drought tolerant than recently introduced turf types. ‘Code 95’, a common type, and ‘Merion’ exhibited high drought resistance and produced turf of good color, texture, and density. Turf mowed at 3.8 cm was more resistant to drought than turf maintained at 1.9 cm.
Little research has been conducted to determine the influence of fertilizer sources and rates on zoysiagrass (Zoysia japonica Steud.) establishment. Our objectives were to determine the influence of slow-release N sources, water-soluble N from urea, and N, P, and K combinations on rate of zoysiagrass establishment. Prior to field planting of zoysiagrass plugs, N rates of 98, 196, and 392 kg·ha-1 from ureaformaldehyde (UF, 38N-0P-0K), isobutylidine diurea (IBDU, 31N-0P-0K, and a composted sewage sludge (1.0N-0.9P-0.2K) were incorporated into a soil with existing high P (193 kg·ha-1) and intermediate K levels (86 kg·ha-1). In a separate study nitrogen from urea (46N-0P-0K, 195 kg·ha-1), P from treble superphosphate (0N-19P-0K, 126 kg·ha-1) and K from muriate of potash (0N-0P-32K, 103 kg·ha-1) also were incorporated before planting. Five months after planting, none of the slow-release N sources or N-P-K combinations had enhanced coverage of the zoysiagrass. No additional fertilizer was applied in the 2nd year. Although statistically significant differences were found among treatments by the end of the 2nd growing season, the actual increases in zoysiagrass coverage provided by the fertilizers were no greater than 5% more than the unfertilized zoysiagrass. In a 3rd study, N (49 kg·ha-1) from urea, applied as a topdressing either once, four, or seven times annually, resulted in a negative linear [coverage = 63.8 − 0.02 (kg N/ha per year), r 2 = 0.57] response in zoysiagrass coverage the initial year, but not in the 2nd year. Nitrogen from urea (49 kg·ha-1) applied bimonthly or monthly the 2nd year had a greater beneficial effect on zoysiagrass growth than topdressing or preplant incorporation of N the initial year.
This 3-year field study evaluated the incidence and severity of dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in six creeping bentgrass (Agrostis stolonifera L.) cultivars maintained as a golf course fairway. Comparison of area under the disease progress curve (AUDPC) data clearly indicted two resistance groups among the six cultivars. ‘Crenshaw’ and ‘Backspin’ were classified as highly susceptible (HS) and the other four cultivars (i.e., ‘Penncross’, ‘Providence’, ‘L-93’, and ‘007’) were classified as moderately susceptible (MS) to dollar spot. In all three study years, there were three epidemics that began in May. Data could not be collected in HS cultivars after the first epidemic in each year as a result of severe damage. In MS cultivars, the first epidemic ended and a second began between early July and late August. The second epidemic ended approximately mid-October and a third epidemic appeared in MS cultivars between late October and early December. The second epidemic was longest and most severe, and the third fall epidemic was least severe and of shortest duration. The first epidemic in HS cultivars developed up to two weeks earlier and progressed more rapidly and severely than in MS cultivars. A growing degree-day (GDD) model, using a base air temperature of 15 °C and a start date of 1 Apr., was accurate in predicting the onset of the first epidemic in HS (60 to 70 GDD) and MS (105 to 115 GDD) cultivars during each of the three study years. Growing degree-day models are greatly influenced by the many microclimates found on golf courses and need to be evaluated for accuracy in diverse environments.
A simple field Pythium inoculation technique is needed to be able to assess cultivars for disease resistance and effectiveness of cultural practices or fungicides in the management of Pythium blight. We assessed two mixtures as inocula [i.e., an infested tall fescue (Festuca arundinacea Schreb.) seed plus wheat (Triticum aestivum L.) bran and an infested rye (Secale cereale L.) plus barley (Hordeum vulgare L.) grain mix], and three covers (black and clear plastic, and a geothermal blanket) for their ease of use and consistency in producing Pythium blight epidemics in perennial ryegrass (Lolium perenne L.) field plots. Both the fescue seed-wheat bran and rye-barley grain inocula provided good media on which to culture Pythium aphanidermatum (Edson) Fitzp. In general, the fescue-wheat bran mix applied at the high level (100 mL/0.9-m2 plots) produced greater blight ratings in perennial ryegrass than did the low level (50 mL/0.9-m2 plot). The fescue-wheat bran also was generally more effective than either rate of the rye-barley mix in blighting turf. All covers enhanced blighting, when compared to the uncovered control, by raising the relative humidity. Covering plots with black plastic following inoculation resulted in greater blight ratings than did covering with either clear plastic or the geothermal blanket.
Sprigs of `Meyer' zoysiagrass (Zoysia japonica Steud.) were treated with urea nitrogen, a biostimulator, and one of three preemergence herbicides or one of two postemergence herbicides to hasten establishment in two field studies. Monthly application of N at 48 kg·ha–1 during the growing season had no influence on sprig establishment the first year, but slightly increased (+5%) zoysiagrass cover the second year. Presoaking sprigs in a solution containing (mg·L–1) 173 auxin and 81 cytokinin, and iron at 1.25 g·L–1 before broadcasting of sprigs, and biweekly sprays (g·ha–1) of 53 auxin and 24 cytokinin, and iron at 0.2 g·L–1 or (g·ha–1) 68 auxin and 36 cytokinin, and iron at 1.45 g·L–1 after broadcasting sprigs had no effect on zoysiagrass cover or rooting. Preemergence and postemergence herbicide use generally enhanced zoysiagrass cover by reducing smooth crabgrass competition [Digitaria ischaemum (Schreb. ex Schweig) Schreb. ex Muhl]. Oxadiazon enhanced zoysiagrass coverage more than dithiopyr, pendimethalin, quinclorac, or fenoxaprop. Oxadiazon and dithiopyr provided similar levels of crabgrass control, but dithiopyr reduced `Meyer' zoysiagrass midsummer root growth. Chemical names used: 3,5,-pyridinedicarbothioic acid, 2-[difluromethyl]-4-[2-methyl-propyl]-6-(trifluoromethyl)-S,S-dimethyl ester (dithiopyr); [±]-ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy] propanoate (fenoxaprop); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); 3,7-dichloro-8-quin-olinecarboxylic acid (quinclorac).