CHARACTERIZATION OF ANASTOMOSIS GROUP-10 (AG-10) OF RHIZOCTONIA-SOLANI

Isolates of Rhizoctonia solani AG-10 have been collected at low freque ncy from wheat and barley roots in Washington and Oregon. In Western A ustralia, AG-10 is collected regularly, but at low frequency, from the roots of cereal, lupin and pasture species. In this study all attempt s to induce AG-10 to sporulate were unsuccessful. However, earlier stu dies by one author (A.O.) confirmed that the teleomorph of AG-10 confo rms with that of Thanatephorus cucumeris. On potato-dextrose agar, myc elial growth of AG-10 is white to light tan with some isolates display ing a yellowish colouration as the culture ages. White, concentric gro wth rings form after 3 or 4 days and the formation of embedded gold, o range-gold or very light tan sclerotia occurs between 14 and 20 days. Sclerotia vary in size from small to large (approximately 2 mm to 8 mm ) and are generally irregular in shape. AG-10 is auxotrophic for thiam ine. AG-10 is non-pathogenic on wheat, barley, lupin, vetch and tomato , but may be a weak pathogen on cruciferous hosts.