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Matthew A. Cutulle, Jeffrey F. Derr, David McCall, Brandon Horvath, and Adam D. Nichols

. However, the major limiting factor to tall fescue’s success as a turf in the transition zone is its susceptibility to the fungal pathogen R. solani Kuhn ( Piper and Coe, 1919 ), which causes the disease brown patch in the summer months. Brown patch is

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Jonathan M. Bokmeyer, Stacy A. Bonos, and William A. Meyer

( Beard, 1973 ). The most devastating disease of tall fescue is brown patch caused by Rhizoctonia solani Kühn. Brown patch can reduce the overall quality and aesthetics of the turf stand ( Couch, 1985 ; Martin and Lucas, 1984 ) and reduce stand density

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Michael A. Fidanza and Peter H. Dernoeden

A field investigation was conducted during 1991 and 1992 to determine the effectiveness of enzyme-linked immunosorbent assay (ELISA) to predict brown patch (Rhizoctonia solani Kühn) infection events in `Caravelle' perennial ryegrass (Lolium perenne L.). Turfgrass samples were collected either between 7:00 and 8:00 am or 4:00 and 5:00 pm, and from plots mowed to a height of either 1.7 or 4.5 cm. Pathogen detection levels were generally higher in am-sampled turf and in plots mowed to a height of 4.5 cm. During 2 years, only 7 of 15 infection events were predicted from samples collected from high-cut turf and only three from samples collected from low-cut turf. While this technology is useful for confirming the presence of R. solani, it was unreliable for predicting infection events.

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Glenn A. Hardebeck, Ronald F. Turco, Richard Latin, and Zachary J. Reicher

Pseudomonas aureofaciens strain Tx-1 is suggested as a biological control for Sclerotinia homoeocarpa (F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) on golf courses. To overcome application difficulties, a field bioreactor is used to grow Tx-1 daily and then inject into nightly irrigation on the golf course. Though Tx-1 shows some promise for disease control in vitro, it is relatively untested under field conditions. We conducted three field experiments to 1) evaluate the efficacy Tx-1 when applied through an irrigation system for the control of dollar spot and brown patch; 2) determine if there is an interaction between nitrogen fertility or fungicides on efficacy of Tx-1; and 3) determine if Tx-1 can extend the duration of dollar spot control by a single application of fungicide. Nightly applications of Tx-1 through irrigation did not affect brown patch on `Astoria' colonial bentgrass (Agrostis capillaris Sibth.) during the 2 years of our study. Tx-1 reduced dollar spot in `Crenshaw' creeping bentgrass (Agrostis palustris Huds.) by 37% in 1998 compared to non-Tx-1 treatments, but Tx-1 had no effect on dollar spot in 1999. Under low disease pressure, Tx-1 increased the dollar spot control of fungicides by 32% and increased the duration of control by 2.6 days. However, Tx-1 had no effect on fungicide efficacy or duration of control later in the summer when dollar spot pressure was high. Fungicides did not negatively affect Tx-1's control of brown patch or dollar spot, nor did fertilizer regime affect brown patch or dollar spot control by Tx-1. Although delivery of Tx-1 in our studies was optimized, disease control was marginal and occurred only under low disease pressure. Therefore, we conclude Tx-1 has limited practical value for turfgrass disease control on golf courses.

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Joon Lee, Jack Fry, and Ned Tisserat

There is interest in identifying cultural practices that may reduce fungicide requirements of creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objective was to evaluate the plant defense activator ASM in combination with 12 biostimulants for the potential to reduce dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in a blend of `Cato: `Crenshaw creeping bentgrass during 2000 and 2001. The experimental design was a split-plot with ASM as the whole plot, and biostimulants as the subplots. ASM was applied biweekly as a.i. at 35 g·ha-1 and biostimulants were applied according to manufacturers recommendations. Sclerotinia homoeocarpa infection centers were reduced by 38% with ASM, but levels were >1500/m2 in Aug. 2000, and turf quality was unacceptable through most of the study period. No suppression of brown patch occurred with ASM. None of the biostimulants reduced dollar spot or brown patch in creeping bentgrass when compared to biweekly applications of soluble N at 4.9 kg·ha-1. Dollar spot suppression achieved with ASM warrants additional studies to determine how it might be used to reduce fungicide inputs on creeping bentgrass putting greens. Chemical name used: acibenzolar-S-methyl (ASM).

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Travis C. Teuton, John C. Sorochan, Christopher L. Main, Thomas J. Samples, John M. Parham, and Thomas C. Mueller

( Puccinia graminis Persoon subsp. graminicola Urban) and dollar spot ( Sclerotinia homoeocarpa Bennett) in Kentucky bluegrass and brown patch [ Rhizoctonia solani (Kühn)] in tall fescue can occur under these stressful conditions ( Landshchoot and Park

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J.H. Dunn, D.D. Minner, B.F. Fresenburg, and S.S. Bughrara

We evaluated the effect of fertilization treatments in combination with clippings disposal on perennial ryegrass (Lolium perenne L.) in two adjacent locations. Clippings left on turf during mowing decreased dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in both locations during three summers compared with clippings removed in mower baskets. However, brown patch (Rhizoctonia solani Kuhn) increased during July and Aug. 1995 when clippings were left on turf. Dollar spot was more severe with N (kg·ha–1·year–1) at 120 compared to 240; brown patch was more severe at 240. While clippings disposal had significant effects on disease incidence, implementation may not be practical because of the contrary responses of the observed diseases to this management approach.

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Mei Zhang and Peter H. Dernoeden

Determining anastomosis groups (AGs) of Rhizoctonia solani Kühn isolates is tedious and time-consuming. Three previously described methods (i.e., cellophane strip, glass slide, petri dish) were compared to determine which was the most rapid and accurate. Colony characteristics also were assessed to tentatively identify AGs. All techniques were accurate. The cellophane strip method was most time-consuming, and the time required for hyphal overlap with the glass slide method was not generally predictable. Pairing isolates in a petri dish containing a thin layer of water agar was reliable and was the simplest technique. There was little variation in colony pigmentation or sclerotia color, shape, or formation patterns within AG-1 IA (n = 34), AG-2-2 IIIB (n = 46), and AG-4 (n = 5); the former two AGs are the ones most commonly isolated from cool-season turfgrasses. Accordingly, R. solani isolates from turfgrasses may be assigned tentatively to an AG based on colony pigmentation and sclerotial characteristics.

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P.H. Dernoeden and M.S. McIntosh

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).

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Eric Watkins and William A. Meyer

Recently, turfgrass breeders have developed many improved turf-type tall fescue (Festuca arundinacea Schreb.) cultivars. Due to the large number of cultivars currently available to turfgrass managers and researchers, we have classified turf-type tall fescue cultivars into six groups based primarily on several morphological measurements. This type of classification is important for turfgrass breeders because many breeding decisions are made based on observations in a spaced-plant nursery. The major objective of this study was to classify tall fescue cultivars and selections based on spaced-plant measurements and to then compare those results with turf performance. A spaced-plant nursery consisting of 36 cultivars and selections was established in September 1998 at Adelphia, N.J. Plant height, panicle length, flag leaf width and length, subtending leaf width and length, and subtending internode length were measured 10 days after anthesis in 1999 and 2000. Additionally, a turf trial was established at North Brunswick, N.J., that included the same 36 cultivars and selections. The turf plots were evaluated for several traits including overall turfgrass quality, density, and susceptibility to brown patch disease. Based on principal component analysis of morphological measurements, along with turf trial data, all cultivars and selections were assigned to one of six groups: forage, early-standard, standard, early semi-dwarf, semi-dwarf, and dwarf. In turf plots, the semi-dwarf, early-semi dwarf, and dwarf groups were the top-performing types in terms of overall turfgrass quality, and the forage and early-standard cultivars had the lowest overall quality ratings. The dwarf types did not perform well under summer stress, especially in terms of brown patch disease incidence. The results of this study suggest that when developing cultivars for higher maintenance situations, turf-type tall fescue breeders should focus on the development of semi-dwarf cultivars.