STUDIES ON THE NEEDLE BLIGHT OF SPRUCE

The needle blight disease of spruce,which is new to china,is described in this paper.It is a common and widespread disease recorded in Europe,North America and Japan.This disease occurs on Picea likiangensis(Fr.) Pritz.and its varieties in Northwestern Yunnan and Western Sichuan.It is caused by Rhizosphaera kalkhoffia Bubak,In late spring,the affected needles become discolored and then purple-brown,and eventually result in the death and cast during the fall,On the affected needles,small,black,stalked pycnidia are formed over stomata in regular rows.The pycnidia contain elliptic or ovoid one-celled spores.This disease may be controlled successfully on ornamental trees by spraying with Bordeaux mixture several times in spring.