FACTORS AFFECTING CONIDIAL EXUDATION AND SURVIVAL, AND ASCOSPORE GERMINATION OF LEUCOSTOMA-CINCTA

Conidia of Leucostoma cincta from sweet cherry were exuded from pycnid ia at 2 to 28 degrees C with an optimum exudation at 20 degrees C. Fre e water was needed for exudation at incubation periods of 6 to 24 h at 20 degrees C. Conidia were exuded at 100% relative humidity during 48 and 72 h of incubation. A large proportion of conidia in dried cirrhi survived summer conditions in the field. As cospores germinated at 10 to 28 degrees C with an optimum at 28 degrees C during incubation tim es of 12 to 24 h. Conidia germinated at 15 to 28 degrees C during an i ncubation period of 24 h. Maximum germination of conidia occurred at 2 8 degrees C during 24 h of incubation. Conidia germinated at 5 to 20 d egrees C when incubation periods were extended to 48 and 72 h. Inocula tions of sweet cherry trees with ascospores of L. cincta resulted in i nfection and development of stem cankers.