The Ascomycete Valsa ceratosperma (Tode:Fr.) Maire [anamorph Cytospora sacculus (Schwein.) Gvritischvili = C. vitis] is a new causal agent of bark canker recently reported on pear growing areas in the Emilia Romagna (Italy). The Regional Plant Protection Service isolated the fungus in 2001 and since then reports have greatly increased in all pear growing areas of the region. This is the first occurrence of Valsa ceratosperma on pear in Europe while Valsa canker is one of the most important diseases of apple orchards in China, Japan and Korea; in these countries the fungus was only occasionally found on pear and quince. The poor knowledge about the disease on pear led us to undertake various studies on the epidemiological and biological aspects. Observations of the disease evolution were carried out in affected orchards, and laboratory and greenhouse assays made it possible to clarify the preferential ways of fungus penetration and the optimal climatic conditions for spore release. It was also investigated whether phloridzin (a dominant component distributed in leaves, stems, fruits and roots of apple tree) plays an important role in Valsa canker on pear as well as that reported on apple in Japanese studies. Preliminary results confirmed that the fungus infects pear trees through wounds such as the pruning ends; the pathogen can be isolated for a distance of about 5 cm beyond visible lesions and cankers develop rapidly in spring and early summer. Cankers with pycnidia appear in a short time only by the inclusion of a small piece of mycelium in a wound created in the trunk of pear in pot. The studies also showed that pycnidia release spores from February to November, conidia ooze gradually from the different pycnidia inside the cankers and the most important factor for fungus sporulation is relative humidity rather than temperature. Neither perithecia formation nor ascospore release were observed on Valsa cankers.
C. Montuschi, M. Collina, L. Antoniacci, E. Cicognani, S. Rimondi, R. Trapella, et al. (2006). Preliminary studies on biology and epidemiology of Valsa ceratosperma (Cytospora vitis), the causal agent of bark canker on pear in Italy.
Preliminary studies on biology and epidemiology of Valsa ceratosperma (Cytospora vitis), the causal agent of bark canker on pear in Italy
COLLINA, MARINA;IOTTI, MIRCO;BRUNELLI, AGOSTINO
2006
Abstract
The Ascomycete Valsa ceratosperma (Tode:Fr.) Maire [anamorph Cytospora sacculus (Schwein.) Gvritischvili = C. vitis] is a new causal agent of bark canker recently reported on pear growing areas in the Emilia Romagna (Italy). The Regional Plant Protection Service isolated the fungus in 2001 and since then reports have greatly increased in all pear growing areas of the region. This is the first occurrence of Valsa ceratosperma on pear in Europe while Valsa canker is one of the most important diseases of apple orchards in China, Japan and Korea; in these countries the fungus was only occasionally found on pear and quince. The poor knowledge about the disease on pear led us to undertake various studies on the epidemiological and biological aspects. Observations of the disease evolution were carried out in affected orchards, and laboratory and greenhouse assays made it possible to clarify the preferential ways of fungus penetration and the optimal climatic conditions for spore release. It was also investigated whether phloridzin (a dominant component distributed in leaves, stems, fruits and roots of apple tree) plays an important role in Valsa canker on pear as well as that reported on apple in Japanese studies. Preliminary results confirmed that the fungus infects pear trees through wounds such as the pruning ends; the pathogen can be isolated for a distance of about 5 cm beyond visible lesions and cankers develop rapidly in spring and early summer. Cankers with pycnidia appear in a short time only by the inclusion of a small piece of mycelium in a wound created in the trunk of pear in pot. The studies also showed that pycnidia release spores from February to November, conidia ooze gradually from the different pycnidia inside the cankers and the most important factor for fungus sporulation is relative humidity rather than temperature. Neither perithecia formation nor ascospore release were observed on Valsa cankers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
