BLACK CANKER AND LEAF-SPOT OF SALIX IN NEW-ZEALAND CAUSED BY GLOMERELLA-MIYABEANA (COLLETOTRICHUM-GLOEOSPORIOIDES)

Two new diseases have been observed attacking willows in New Zealand. In the first instance black stem cankers formed on S. matsudana x S. alba x S. alba cultivars, eventually killing them. In the second instance foliage of S. gooddingii and S. amygdaloides was attacked and premature defoliation occurred. Morphological studies and host inoculations established that Glomerella miyabeana (Colletotrichum gloeosporioides anamorph) was the causal agent of both diseases. Foliage of cultivars exhibiting stem cankering was not attacked nor were stems of cultivars with foliar lesions. Electron microscopic studies showed that conidia of Colletotrichum gloeosporioides formed phialidically within acervuli and conidial dimensions varied significantly with host.