First Report of Anthracnose on Weeping Willow in Greece.

Abstract

A serious disease of weeping willow (Salix babylonica) trees in home and public gardens was observed in the Chalkidiki region (northern Greece) during the spring of 1995 and 1996. Purplish-brown or black, small necrotic spots appeared on the leaves and often on leaf veins. Leaves became distorted and fell. Small, light, sunken cankers with dark brown rim and paler center, elongated in shape, appeared on the young shoots and on the leaf petioles. Severely affected shoots lost their weeping habit on which the tree's ornamental value is based. Whitish acervuli covered the leaf spots and the cankers. Masses of conidia emerged from the acervuli under high relative humidity conditions. The conidia were hyaline, clavate to pyriform, two-celled (unequally), measuring 14 to 19 × 4 to 7 μm, and belonged to the fungus Marssonina salicicola (Bres.) Magnus (1), which is the anamorph of the ascomycete Drepanopeziza sphaeroides (Pers.) Hohnel, the cause of anthracnose of weeping willow. The outbreak of the disease can be attributed to the rainy weather (70.5 and 105.5 mm of rain occurred in spring 1995 and spring 1996, respectively) and temperatures of 20°C. The disease is known to cause serious damage in some European countries, Canada, Egypt, Argentina, and New Zealand. This is the first report of the disease in Greece. Reference: (1) I. Vegh and J. Velastegui. Cryptogam. Mycol. 4:345, 1983.