银杏叶枯病初侵染源的研究

１９８９－１９９２年间，以银杏的冬芽、幼叶、嫩叶以及越冬后的落叶等为试验材料进行研究。结果表明，银杏叶枯病的三种病菌均能在冬芽和落叶上越冬。当春季节萌发后，银杏叶枯病的主要病原链格孢菌能转移到部分嫩叶上，继续进行潜伏侵染，但其数量显著下降。３－６月间，越冬后落叶上的链格孢菌可以大量形成呈丛状的分生孢子梗，并不断产生新的分生孢子。上一年在落叶上产后的分生孢子，越冬后仍具有一定的发芽率。就病害的侵染源

STUDIES ON THE PRIMARY SOURCE OF INFECTION OF THE LEAF BLIGHT DISEASE OF GINKGO

The experiment was carried out in the period from 1989 to 1992. The author took the winter buds, Young leaves,tender leaves,tender leaves and overwintering fallen leaves of Oinkgo as experimental materials. The results demonstrated that all the three pathogens (Alternaria alternata, Col-letotrichum gloeosporioides, Pestalotia ginkgo) of ginkgo leaf blight overwintered on winter buds and fallen leaves in the form of mycelium. During the spring (after the germination of buds), the main pathogen-A. alternata of ginkgo leaf blight could be transferred to a part of tender leaves and continued its incubating infection, But there was a marked drop in quantity. During the months of March to June, clumped conidiophores were formed by A. alternata on the overwintering fallen leaves, and new conidiodpores constantly emerged. The conidiospores formed on the fallen leaves last year still retained the germination capacity to a certain degree. So far as the carriers were concerned, the winter buds could not be compared with fallen leavs in the sense of infectious source.