Abstract

A series of studies are reported, including a survey of nurseries and plantations in Kerala before and during the monsoons of 1979-83, in vitro conidial germination, infection of 4-month-old E. grandis seedlings by spraying with a conidial suspensionof C. [Calonectria] quinqueseptatum, and screening of 8 provenances of E. grandis and 7 provenances of E. tereticornis for susceptibility to a conidial spray of C. quinqueseptatum. Nine species (including Cylindrocladium clavatum, C. scoparium, C. ilicicola, C. parvum, C. floridanum, C. camelliae, C. curvatum and C. [Calonectria] theae) were found to be associated with Eucalyptus spp., causing a complex of damping off, stem canker, leaf and shoot blight in nurseries. In plantations, only leaf spot, leafblight and shoot dieback were common. Leaf diseases usually began to appear on lower branches indicating infection from the soil. In areas of high humidity, infection could be severe, producing complete defoliation. In younger