甘肃省西瓜枯萎病病原菌鉴定及生物学特性测定

本文报导了西瓜枯萎病在甘肃的分布和危害。经采集培养、单孢分离,32个标样(320个病组织块)中,镰孢属真菌占73.1％,其余为链格孢等。按C.Booth标准条件培养,经致病性、专化型测定,甘肃省酒泉、民勤、兰州西瓜枯萎病的病原为尖镰孢西瓜专化型(Fusarium ox-ysporium f.sp. niveum)。该菌分生孢子的萌发需要液态水;分生孢子在pH4.53～9.18均可萌发,最适pH5.91;适宜浓度的马粪、土壤、蔗糖、瓜叶汁液对孢子萌发均有刺激作用,8小时内高出对照(清水)22％以上。刺激作用在4小时前表现最为明显;在相同条件下,大型分生孢子较小型分生孢子萌发快;4～8小时是大型分生孢子萌发的对数增长期;小型分生孢子萌发率缓慢增长。

Identification and Biological Characters of the Causal Organism of Watermelon Wilt Disease

This paper reports the distribution and the economic losses of watermelon wilt disease in Gansu province. The results showed that the isolated rate of Fusarium spp was 73. 1%, and the other fungi were Alte- rnaria etc. According to the cultural, morphological, monospore isolation, pathogenicity and formae specialis studies, under the standard condition of C. Booth, the causal organism was identified as Fusarium oxysorium f. sp. niveum. Two kinds of conidia, macroconidia and microconidia, had to germinate in free water. Germination occured at pH 4. 5～9. 2, but the op- timum was at pH 5. 9. The fitter dilution of horseshit, soil, sugar, water- melon leave might stimulate the germination of the conidia. This effect was most obvious at first 4hr. Under the same condition, the germination of macroconidia was faster than microconidia and its logarithmic growth period was in 4～8 hr.