During surveys on Verticillium wilt of olive trees carried out in Umbria (central Italy) some plants showed a progressive withering of twigs and young branches. Earliest symptoms appeared in the spring 1991; leaves on infected twigs lost their deep green colour, turned brown and remained attached to affected twigs. Some twigs of heavily-infected trees sometimes showed longitudinal stripes of variable shape and length and a brown discoloration of the xylem. The disease seems to develop very slowly and rarely kills the trees. Our trials have proven that the disease was caused by Phoma incompta Sacc. et Mart. The fungus was examined for colony morphology, temeprature response and pathogenicity. Significant differences were observed among various media. Best growth and profuse sporulation were obtained on V8 and Czapek agar. The optimum temperature for growth reduced colony growth and pycnidia formation. No growth was observed at 35°C. The optimum pH for the gowth of P.incompta on all tested media ranged from 6.5 to 7.5. Of four inoculation methods used only transplanting in inoculated soil was successful. All varieties (Frantoio, Leccino, Moraiolo and clone I-77) were susceptible to the pathogen; leaf symptoms, defoliation and vascular discoloration began to appear approximately 30 days after inoculation.
Phoma incompta Sacc. et Mart. a new olive parasite in Italy
TOSI, Laura;ZAZZERINI, Antonio
1994
Abstract
During surveys on Verticillium wilt of olive trees carried out in Umbria (central Italy) some plants showed a progressive withering of twigs and young branches. Earliest symptoms appeared in the spring 1991; leaves on infected twigs lost their deep green colour, turned brown and remained attached to affected twigs. Some twigs of heavily-infected trees sometimes showed longitudinal stripes of variable shape and length and a brown discoloration of the xylem. The disease seems to develop very slowly and rarely kills the trees. Our trials have proven that the disease was caused by Phoma incompta Sacc. et Mart. The fungus was examined for colony morphology, temeprature response and pathogenicity. Significant differences were observed among various media. Best growth and profuse sporulation were obtained on V8 and Czapek agar. The optimum temperature for growth reduced colony growth and pycnidia formation. No growth was observed at 35°C. The optimum pH for the gowth of P.incompta on all tested media ranged from 6.5 to 7.5. Of four inoculation methods used only transplanting in inoculated soil was successful. All varieties (Frantoio, Leccino, Moraiolo and clone I-77) were susceptible to the pathogen; leaf symptoms, defoliation and vascular discoloration began to appear approximately 30 days after inoculation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
