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Preliminary Studies on Binucleate Turfgrass Pathogens That Resemble Rhizoctonia solani. P. L. Sanders, Research Assistant, Pesticide Research Laboratory and the Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802; L. L. Burpee(2), and H. Cole, Jr.(3). (2)(3)Research Assistant, and Professor, respectively, Pesticide Research Laboratory and the Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802. Phytopathology 68:145-148. Accepted for publication 20 June 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-145.

Isolates from turfgrass showing various foliar symptoms in November, 1974, 1975, and 1976, resembled Rhizoctonia solani in hyphal and cultural morphology. A collection was made of similar isolates from various hosts. These isolates did not anastomose with R. solani testers in anastomosis groups 1-4. Eighteen isolates were binucleate and had dolipore septa. The perfect state was induced in four isolates; these isolates were identified as species of Ceratobasidium based on basidial morphology. The 18 isolates were tested for anastomosis with each other in all possible pair combinations and were separated into four anastomosis groups. On potato-dextrose agar (PDA), optimum temperature for growth was 21-23 C for four binucleate isolates from turfgrass, and 28 C for the remaining 14 isolates and R. solani. In greenhouse pathogenicity tests on pot-grown, seedling bentgrass, R. solani from turfgrass was not active at 10 C, but produced severe foliar blighting from 16-38 C. Binucleate isolates from turfgrass in Pennsylvania and New York produced severe foliar blight at 10-27 C, but were not pathogenic at higher temperatures. Binucleate isolates from hosts other than turfgrass, all from southern states, produced foliar blighting from 21-38 C, but were not active from 10-20 C. Benomyl, chlorothalonil, RP 26019, anilazine, PCNB, and chloroneb, tested in PDA for activity against 18 binucleate isolates, gave variable results. Of the six fungicides tested, chlorothalonil and chloroneb showed the greatest overall activity in reducing fungal growth.

Additional keywords: Thanatephorus cucumeris, cool-weather Rhizoctonia, Poa pratensis, Agrostis spp., Festuca arundinaceae, Ceratobasidium.