STUDIES ON THE NEEDLE RUST OF KETELEERIA EVELYNIANA MAST.AND ITS PATHOGEN

Systematic studies on the needle rust of Keteleeria evelyniana are reported in this paper.According to the disease investigations and artificial inoculations,it has been affirmed that Chrysomyxa keteleeriae(Tai) Wang et Peterson would be regarded as an automicrocyclic rust.The studies on the biological feature of the pathogen show that the optimum temperature and relative humidity of teliospore germination are about 20℃,100% RH or in dis-tilling water drops,but basidiospores about 24℃ and 75% RH.Direct light(8-w fluorescent lamp) can inhibit germination,especially that of teliospore.Telia appear from the last twenty days of April to the first and second ten days of June and have no dormant period.Basidiospores are the first infectious source and infect those younger needles.The fungus overwinters in the infected needles as mycelium.New inoculum is not produced in the same year any more.So the needle rust of Keteleeria evelyniana would be regarded as a singlecyclic disease.Thus systematic studies on the disease and its pathogen are made for the first time both at home and abroad.