贵州烤烟棒孢霉叶斑病的发生与发展

通过田间试验研究了贵州烤烟棒孢霉叶斑病的发生与发展、潜育期和病原菌生活史时间,结果表明:①在6月下旬前(大田前期)病害发展缓慢,6月底至7月上中旬的较高温季节,若遇连续阴雨天气且菌源量较大时,病害发展迅速;若菌源量较小,病害将呈逐渐发展的趋势;②随着与发病中心距离的增大,病情指数明显下降;③烟株接种病菌后保湿38h,5月末至7月中旬该病害在田间的潜育期为16~33h;④在5月底、6月底和8月上旬田间接种产生的较大叶斑中,取病斑样后保湿2d镜检,在出现少数病斑的样本上产孢(病原菌生活史)的时间分别为接种后11、8和7d。

Occurrence and Development of Leaf Spot Caused by Corynespora cassiicola in Guizhou Fluecured Tobacco

The occurrence,development,latent period,pathogen's life cycle of leaf spot caused by Corynespora cassiicola in Guizhou fluecured tobacco were studied in the field.The results showed that: 1) the disease developed very slowly by the late June(5 to 6 weeks after transplanting);from the end of June to mid July,in persistent rainy days,the disease developed rapidly while source of infection was rich,it developed gradually if the source of infection was not enough;2) the disease index obviously decreased with the increase of distance from disease focus;3) from the end of May to mid July,the latent period of leaf spot was 16 to 33 hours when the tobacco plant was kept moisture for 38 hours after inoculating;4) when the bigger spots on the leaves inoculated in the ends of May and June and the early August were sampled,kept moisture for 2 days and then examined under microscopy;it was found that on the samples with a few spots,spores appeared in 11,8 and 7 days after inoculating,respectively.