PAPILIONACEAE. Vinca major: Wellington, Upper Hutt, 20 m. SOLANACEAE. Solanum tuberosum: Auckland, Mt. Albert, 100 m.

Hymenophore annual, effused, readily lifting, spreading over stems of living plants, arachnoid-mucedinioid, forming irregular linear areas to 15 cm long, 2-10 mm wide; hymenial surface white, drying cream or greyish, irregularly slightly tufted; margin thinning out, concolorous, arachnoid. Context white, of a few repent hyphae 8-10 µm diameter, commonly 7-8 µm, walls 0.5 µm thick, without clamp connections; fertile hyphae erect, cymose, ends of branchlets bearing clusters of basidia and paraphyses. Basidia subclavate, some cylindrical, 12-18 x 8-10 µm, bearing 3-4 spores on sterigmata which may attain a length of 15 µm. Paraphyses subclavate, 6-10 x 6-8 µm. Spores elliptical or oblong, some obovate, apiculate, 7-11 x 5-6.5 µm, walls smooth, hyaline, 0.5 µm thick.

DISTRIBUTION: Probably cosmopolitan.

HABITAT: Effused on stems and leaves of living plants.

Recognised by the elliptical spores borne on sterigmata which, at first stout and short, elongate shortly before spores are formed to reach a length of 15 µm. Not infrequently one sterigma is suppressed, basidia then bearing three spores. Although the Pellicularia stage is comparatively rare, the hyphal stage of the species is a well known parasite of many plants. On potato tubers the fungus forms black sclerotia, this stage being long known under the name of Rhizoctonia solani. In a previous paper (Cunningham 1953, c, p. 328) Corticium praticola was listed as a synonym. Flentje has shown that this species, to which he gave the name Pellicularia praticola (Kotila) Flentje (1956, p. 353) may be separated by cultural characters and several minor morphological features.

TYPE LOCALITY: Ecuador, South America.

Pellicularia filamentosa is an important fungus in potato crops. Chamberlain (1931) suggested for its control treatment of seed with acidified mercuric chloride dip some months before planting. In recent years Booth (1965) recommended a dip in mercury-based compounds as a pre-planting treatment for seed potatoes; he emphasised that dipping should be done before the tubers have sprouted. It is associated with brown patch on lawns and greens (Brier, 1935; and Arnold and Brier 1961). In pastures in wet humid weather it may rot areas of grass. Ward (1926) noted that Rhizoctonia could be a problem in Lucerne pastures on areas with high rainfall. Wratt (1956) and Blair and Morrison (1949) showed its importance as a pre-emergence rot in seedlings of cereals. It is also important in nursery beds of seedlings of forestry trees such as Pinus radiata, P. nigra, and Pseudotsuga menziesii (Thulin, Will, and Bassett 1958). It is common in warm dry weather in seed beds of crops such as lettuce, tomatoes, and cabbage. It was also noted in nursery beds of citrus and peach seedlings and can be of considerable economic importance in nursery seed beds, especially in humid periods in summer months. Except for Agathis australis and Hydrocotyle sp., all hosts are introduced.