水杉赤枯病病原初探

<正>水杉赤枯病在江苏各地普遍发生,危害水杉苗和大树。春季,

A PRELIMINARY STUDAY OF ETIOLOGY OF METASEQUOIA BLIGHT

Metasequoia blight is a widespread disease in all parts of Jiangsu province. The disease attacks young seedlings and older trees as well. In the spring the fungus chiefly infects the leaf-tip. Diseased trees show wilting leaves, and produce leaf spots from pale brown to brown or form small diseased spots on the other portion of the leaf. In the autumn the fungus forms its fructifications on diseased leaves, usually producing two kinds of fruiting bodies like small black spots and villus. Results of tissue isolations and inoculation experiments show that the disease is mainly caused by Pestalotia foedans Sacc. et Ell. and Alternaria tenuis Nees. Both of the pathogens are found on diseased leaves all the year round. The frequency of the pathogens present on the diseased leaves varies with the different periods of the incidence of the disease. The pathogen is apt to infect the plant through wounds, and overwinters on deciduous diseased leaves.