Epidemiology and Etiology of Zoysiagrass Diseases in Northwest Arkansas

Epidemiology and Etiology of Zoysiagrass Diseases in Northwest Arkansas

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Large patch is caused by the fungus Rhizoctonia solani AG 2-2 LP. The disease occurs during spring, late summer, and early fall on warm season turfgrasses in the transition zone and is quite destructive to zoysiagrass in Northwest Arkansas. Symptoms include irregular patches up to several meters in diameter and distinct lesions on the leaf sheaths and stems. Management of large patch with fungicides is expensive and complete control is almost never achieved. This has led others to suggest that other microorganisms are associated with the disease. The objectives of this study were to determine if patches occurred season after season in the same location and if other microorganisms contributed to the severity of large patch disease. To accomplish the first objective, test plots were established on fairways at two golf courses where disease was active. Each plot was 7 x 14-m and patch locations were recorded on a 10cm grid. Data were recorded in spring 2007, spring and fall 2008, and spring 2009. The number of diseased points increased with each sequential recording and many occurred at or contiguous to diseased points from the previous season. To accomplish the second objective, isolates were collected in spring 2007 from leaf sheaths and in spring 2008 from leaf sheaths, stems and rhizomes of zoysiagrass with active large patch disease. Isolates were grouped by morphological characteristics, and isolates from each group were tested for pathogenicity on zoysiagrass cultivars 'Meyer' and 'Cavalier'. Seven groups (Rhizoctonia solani AG2-2 (LP), Gaeumannomyces graminis var. graminis, three Fusarium spp. , one Pythium sp. and an unidentified sterile white basidiomycete) were pathogenic and were re-tested alone and in combination with R. solani AG2-2 (LP) on both cultivars. No combination of any isolate and R. solani significantly increased disease over R. solani alone but G. graminis var. graminis and R. solani AG2-2 (LP) caused significant disease alone and were not antagonistic to one another when inoculated on the same plant. However, the co-inoculation of R. solani AG2-2 (LP) and the sterile white basidiomycete lessened disease.MATERIALS AND METHODS The Blessings Golf Club in Fayetteville, AR (The Blessings), and Shadow Valley Country ... A 1-m- square template constructed of PVC pipe and string was used to divide 1-m squares into 100 10-cm squares (Fig .

Title:Epidemiology and Etiology of Zoysiagrass Diseases in Northwest Arkansas
Author:Terry N. Spurlock
Publisher:ProQuest - 2009


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