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.