Characterization of Rhizoctonia solani associated with Sore Shin and Leaf Spot Symptoms on Tobacco in Zimbabwe

Abstract

The relationship between Rhizoctonia solani isolates derived from leaf spot and sore shin symptoms on tobacco was characterized by determining nuclear number, hyphal diameter, anastomosis grouping (AG) and pathogenicity. The leaf spot isolates had significantly more nuclei per cell, and wider hyphae than the sore shin isolates. Anastomosis pairings with known tester strains confirmed the leaf spot isolates to be AG 3, and the sore shin isolates to be AG 4. Pathogenicity testing indicated that the leaf spot isolates were pathogenic to all parts of the plant, whereas the sore shin isolates tended to form lesions on stems only.

Characterization of <i>Rhizoctonia solani</i> AG-3 Isolates Causing Target Spot of Flue-Cured Tobacco in China

“…This is a detail investigation to provide evidence of the relative AG composition of R. solani populations causing disease in China tobacco. So far isolates belonging to AGs 1 through 5 of R. solani have been reported as causal agents of tobacco diseases [12,15]. Anastomosis pairing revealed that all isolates were belonging to AG-3.…”

“…Pathogencity tests were performed on detached tobacco (cv. nc89) leaves; 4-week-old seedlings were planted in a greenhouse (25-35°C day/15-20°C night temperatures) with no additional lighting according to Mopfu and Julian [12]. YC-9 isolates was retrieved from slant tube preservation and grown on PDA at 28℃ in the dark for 5 days.…”