Studies on the branch gall disease of keteleeria evelyniana

A new disease, the branch gall of Keteleeria evelyniana Mast. is described in this paper. It has never been recorded befere. This disease occurs commonly on Keteleeria evelyniana in middle Yunnan. It is caused by Libertella wangii Ren et Zhou. The galls which occurs on branches and occasionally on young stems, are subglobose in shape with a rough surface. They are usually encircle the branch and may attain the size of 20 cm in diameter. The acervuli of the fungus are embedded in the epidermis of the gall, commonly along the epidermis fissures. The overwintering of this fungus is by way of forming fruiting bodies in epidermis and as vegetative mycelium in the gall. During wet weather, in late spring and early summer, the fruiting body oozes in the thin threads of spores which are spreadby rain and rainsplash and windblown Field observations indicate if the spores landed on a terminal bud of young shoot they can cause an infection. Galls formed on young stems should be cut out and destroyed in dry season. If necessary, the young trees should be periodically sprayed with a fungicide in Iate spring.