FACILITATING ANASTOMOSIS GROUPING OF RHIZOCTONIA-SOLANI ISOLATES FROMCOOL-SEASON TURFGRASSES

Determining anastomosis groups (AGs) of Rhizoctonia solani Kuhn isolat es is tedious and time-consuming. Three previously described methods ( i.e., cellophane strip, glass slide, petri dish) were compared to dete rmine which was the most rapid and accurate. Colony characteristics al so were assessed to tentatively identify AGs. All techniques were accu rate. The cellophane strip method was most time-consuming, acid the ti me required for hyphal overlap with the glass slide method was not gen erally predictable. Pairing isolates in a petri dish containing a thin layer of water agar was reliable and was the simplest technique. Ther e was little variation in colony pigmentation or sclerotia color, shap e, 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 isol ated from cool-season turfgrasses. Accordingly, R. solani isolates fro m turfgrasses may be assigned tentatively to an AG based on colony pig mentation and sclerotial characteristics.