Factors affecting Chondrostereum purpureum infection of Salix

Factors affecting Chondrostereum purpureum infection of Salix were studied in the laboratory and field. Basidiospores passively entered all xylem tissues but not cambial, phloem or bark tissues. A small number entered stems up to 70 mm from the wound surface although most were retained within tissues 30 mm from the surface. Basidiospores required free water for germination and the optimum temperature for germtube extension was 26°C. Hyphae ramified extensively throughout xylem tissues eventually plugging vessels. Cell walls and starch granules were penetrated with enzymatic assistance. The depth of C. purpureum penetration was affected by wound diameter and inoculum concentration but not stem age. Wounds of Salix were susceptible to C. purpureum throughout the year and greater depth of penetration was obtained using mycelium as inoculum than basidiospores. The depth of C. purpureum penetration decreased with duration of wound exposure prior to inoculation. A characteristic flora of saprophytic fungi and bacteria inhabited wound tissues.