Parasitic on stems and roots of (1) Beta vulgaris, Canterbury, Ladbrooks, Jul 1956, H. C. Smith, 19069; (2) Daucus caroita. Otago, Dunedin, Jun 1954, A, G. Kenelley, 13239: (3) D. carota, Waitati, Jul 1958, A.G. K., 18501; (4) Solanum tuberosum, Auckland, Pukekohe, Oct 1961, J. M. Dingley, 21857.

Fructifications arid, encrusting, indeterminate, purplish, violet or reddish brown when fresh, often pruinose at maturity, frequently losing violet tints when dry; margins pallid, byssoid. Internal hyphae dark red-or purple-brown, septate, 5-7-(9.5) µm. diam., clamp connections absent. Probasidia subclavate to clavate, straight or tortuous, 18-26 x 6-8 µm., soon collapsing. Metabasidia cylindrical, at first straight, becoming recurved apically, typically transversely 3-septate, 52-69 x 6-8 µm; sterigmata 2-4 per basidium, subulate, to 40 x 3-4 µm Basidiospores ovate, oblong-elliptical, or occasionally curved-cylindrical, hyaline, bluntly apiculate, 9.9-13-(14.5) x 5-6.5-(7.5) µm. Germination not observed.

Plant debris or encrusting living plants.

Buddin & Wakefield, Trans. Br. mycol. Soc. 12: pi. II, f. 1-8. pl. 12, f. 13-30. 1927.

Present information suggests that violet root rot, caused by Helicobasidium brebissonii, is not an important disease of field crops in New Zealand. The species was first recorded in the country by Kirk (1907) as Rhizoctonia violacea.

TYPE LOCALITY: Northern France.