Investigation And Research Of Uncinula Necator Cleistothecia In China

The investigation of Uncinula necator cleistothecia was taken on the vineyards in China from September to December in 2004. And the analysis between initiation of Uncinula necator cleistothecia and the climate was conducted. In the lab, release, germination and pathogenicity of ascospores of Uncinula necator were studied. Otherwise, the detached-leaf method for culturing Uncinula necator was studied.Results indicated that:(1) For the greenness preservative and the development of Uncinula necator, absorbed cotton in petri dishes containing benzimidade brought the best results under sterilized conditions. The Younger leaves gave better results than older ones. The optimum concentration for benzimidade was 30 ~ 50 mg.L~-1 ,especially when the concentration for benzimidade was 50 mg.L~-1, the percentage of greenness area was more than 90% after 15 days. The leaves cultured in HB medium with 0.01 mg.L~-1 IAA grew healthily. The time of the greenness preservative was more than 2 months.(2) Uncinula necator cleistothecias were found in the vineyards in Yuan Dang village Yao county Shaanxi province in China. The number of cleistothecias was numerous. This is the fisrt report of Uncinula necator cleistothecia in China.(3) The initiation of Uncinula necator cleistothecias was from August to September. The main reason of the initiation of Uncinula necator cleistothecia was temperature daily range.(4) Cleistothecia gregarization, globe or approximately globe, dust-colour, 75.0~125.0um in diameter. Appendage 5~19, acerose, smooth, basin brown, top colorless and limpidity, septate, top helix. Ascocarp 3 ~ 5(med.num.4), approximately globe or pollywog, 32.5~70.0x5~25um in diameter, colorless, pedicellate, pedicellate 4~8μm long. Ascospore 2~8, ellipse, ovum or approximately globe, colorless, 6.0~20.0×5.0~16.0μm in diameter. This description was consistent with that in 《 FLORA FUNGORUM SINICORUM -ERYSIPHALES》 .(5) In the vineyards, Uncinula necator cleistothecias survived on fallen leaves in winter. Cleistothecias were put into water; the survival time of them was only 2 days. Free water was required for ascocarp dehiscence and ascospore discharge. Between storage conditioninvolving wetting treatment at 20 °C and at 5°C,the survival of cleistothecias has no significant difference. Mature cleistothecias were placed in ascospore releasing conditions (100%RH at 20 °C), in the first 48 h, the number of ascospores increased steadily. Most ascospores released between 36 and 60h. Cleistothecias collected in the vineyards cannot be pathogenic in the lab.