Dueterophoma - a fungal pathogen of chrysanthemum previously unrecorded in Australia

Abstract

The fungus Deuterophoma has been proved to be a pathogen of chrysanthemums in Victoria. It was isolated from a number of varieties in each of five Melbourne nurseries from which collections of chrysanthemum were made, and also from one variety growing in a Rutherglen home garden. In pathogenicity tests Deuterophoma was found to rapidly invade injured roots and move info the stems from which it could be readily re-isolated. Chrysanthemum infected with Deuterophoma do not show symptoms on the current season's growth. However, the fungus weakens the stools which may, die or regenerate slowly after being cut back in the autumn. Deuterophoma has been recorded previously only in Californian and in Illinois on chrysanthemums originating from California. In the nursery from which the fit isolates were obtained it was prevalent in chrysanthemums recent4 introduced from California. As it is impossible to detect Deuterophoma from visual observation of the current season's growth, the necessity of importing chrysanthemums from pathogen free sources is stressed. The use of pathogen free stocks coupled with soil sterilization and nursery hygiene is suggested as a means of control of Deuterophoma.