DESCRIPTION AND PATHOGENICITY OF CALONECTRIA-CLAVATA SP-NOV

A Cylindrocladium sp., now identified as C. clavatum, was isolated fro m root and organic debris removed from nonsterilized peat from souther n peninsular Florida (Lee County). The fungus was later isolated from roots and stems of Callistemon viminalis grown in soil mixes containin g the same peat. Pairing of the two mass isolates on propylene oxide-f umigated woody stem pieces of Arachis hypogaea on water agar and on st em pieces of Rhododendron sp. on water agar yielded perithecia under a mbient laboratory conditions. Pairing (all possible combinations) of 2 7 monoascospore cultures derived from these perithecia resulted in the production of perithecia in 170 of 351 crosses. Perithecia were not p roduced in unpaired cultures, thus indicating a bipolar heterothallic sexual compatibility. Calonectria clavata sp. nov. is proposed for the binomial of the heterothallic sexual state which is heretofore undesc ribed. This fungus is shown to be a pathogen on Eucalyptus viminalis s eedlings.