Abstract

155p Extensive survey of nurseries and plantations through out Kerala State revealed nine species of Cylindrocladium associated with diseases of Eucalyptus spp. Cylindrocladium leaf blight (CLB) was the major disease affecting all growth stages of eucalypts and C. quinqueseptatum was the dominant species. In vitro germination of conidia of C. quinqueseptatum began after 4.5 h of incubation and attained about 95 within 8 h; germination was optimal at 25 degree Celtius. Conidial germination on the intact leaves of 2-month-old E. grandis occurred after 3 h of incubation. Rainfall influenced considerably in increasing the severity of CLB. Susceptibility of 36 provenances belonging to 16 species of Eucalyptus to CLB caused by Cylindrocladium quinqueseptatum,C. Clavatum and C. ilicicola differed significantly in detached leaf inoculations. Seventy stock cultures of C.quinqueseptatum (CQ) were distinguishable into 10 groups based on cultural characters; each group of cultures showed significant differences incultural characters on nine growth media used. A total of 22 fungicides were evaluated in vitro for their efficacy. Though a number of fungicides were found effective only carbendazim provided complete inhibition of CQ, CL and CC in soil-fungicide screening technique; carbendazim was also highly effective against CF and CP. Nursery practices influenced incidence and severity of diseases and growth of seedlings of E. grandis. Direct sowing technique was found to be a feasible alternative for large-scale planting programme