Characterization of Rhizoctonia solani isolates from rice in Arkansas

Rhizoctonia solani causes sheath blight, one of the most serious diseases of rice. Over 200 isolates of Rhizoctonia-like fungi were obtained from infected rice samples in Arkansas, of which 103 isolates were identified as R. solani using a rDNA-ITS marker. The remaining isolates were either R. sativ...

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Bibliographic Details
Published in:Phytopathology 2004-06, Vol.94 (6)
Main Authors: Wamishe, YA, Jia, Y, Singh, P, Cartwright, R D
Format: Article
Language:English
Subjects:
Rhizoctonia solani
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Summary:Rhizoctonia solani causes sheath blight, one of the most serious diseases of rice. Over 200 isolates of Rhizoctonia-like fungi were obtained from infected rice samples in Arkansas, of which 103 isolates were identified as R. solani using a rDNA-ITS marker. The remaining isolates were either R. sativa oryzae or other sclerotia-forming fungi. To determine growth rates of R. solani isolates in vitro, the isolates were grown on potato dextrose agar in a completely randomized design at 30 degree C with three replications and hyphal growth after 24 + 3 h was recorded. There were significant differences among isolates for hyphal growth rate. Three fast, two intermediate, and three slow growing isolates were selected for a pathogenicity test, and all eight produced necrotic lesions on detached rice leaves. The selected isolates produced typical sheath blight symptoms on whole plants when leaves were inoculated with hyphal agar disks (pressed with thumb). Preliminary greenhouse inoculations showed positive correlation of hyphal growth rate with lesion length in most cases. Further characterization of the selected isolates and development of an inoculation technique for screening rice cultivars for resistance are underway and will be reported.
ISSN:0031-949X