Sphaeropsis canker, a new disease of cypress in Greece

The fungus Sphaeropsis sp. is reported for first time in Greece to cause ca nkers on Cupressus sempervirens. The cultural characteristics on PDA, spore shape and size and canker morphology were identical to those of the fungus described as Diplodia pinea f. sp. cupressi In Israel. The cankers of Spha eropsis sp. are characterized by resin exudation, with fissuring of the bar k over a dry sector of the wood. The pathogenicity of the Sphaeropsis sp. w as proved by artificial inoculations on selected cypress clones resistant a nd susceptible to Seiridium cardinale. The mean canker length of the suscep tible clone was significantly more than that of the resistant clones. It ap pears that the defence reaction in cypress against both fungi is similar. I n artificial inoculations on Pinus halepensis and Pinus pinea, Sphaeropsis sp. was nonpathogenic. During a 3-year period, in an experimental plot in w estern Peloponnese, the fungus spread from one, initially, omega 13 cypress clones. Drought stress during the summer appears to be the main factor pre disposing the cypress plants to become susceptible to the fungus.