四川烤烟赤星病的生物学特性及药剂筛选

为明确四川烤烟赤星病发生规律和生物学特性并筛选高效防治药剂，连续3年在四川省泸州市、凉山州、攀枝花市、广元市、宜宾市等5个主要植烟区对烟草赤星病发生情况进行调查，并在烟叶成熟期采集典型患病烟叶进行病原菌分离培养，通过宏观形态学、显微形态学及分子生物学鉴定其种类并测定菌落生长速率和萌发率，同时在烟田开展烟草赤星病高效防治药剂筛选。结果表明，5个烟区采集的赤星病样均属于链格孢属（Alternaria spp.）真菌，各烟区所采集分离的赤星病菌在SDAY培养基上菌落直径、产孢量和萌发率差异均不显著。5个烟区均发生烟草赤星病，整体发病规律为：每年6月底至9月初，烟田病情指数随着时间的推移逐渐增加，每年8月份，5个植烟区烟草赤星病病情指数显著高于7月份并趋于峰值。10%苯醚甲环唑水分散粒剂和40%菌核净可湿性粉剂对烟草赤星病均有较好的防治效果（防效均大于60%）。

Biological Characteristics and Fungicide Screening of Tobacco Brown-Spot Disease in Sichuan Province

In order to determine the periodic occurrences, biological characteristics and high effective fungicides of tobacco brown spot disease in Sichuan Province, systematic investigation was carried out to study the occurrence of brown spot of tobacco for three consecutive years in 5 major planting areas of Sichuan Province including Luzhou, Liangshan, Panzhihua, Guangyuan and Yibin. Tobacco samples with typical symptoms of brown spot were collected at maturity. To identify the causal species of the disease, colonies isolated from brown spot-infected tobacco were studied using macromorphology, micromorphology and molecular biology methods and growth rate and germination rate determined. At the same time, the screening of high efficiency emergency chemicals for brown spot of tobacco was conducted in tobacco fields. The results showed that the causal pathogens identified from tobacco samples with typical symptoms of brown spot from the 5 major planting areas of Sichuan Province were all Alternaria spp. There were no significant difference in colony diameter, spore production and germination rate among the isolates of Alternaria spp. on SDAY media. The disease index of Alternaria spp. increased gradually with time from the end of June to September every year in the 5 growing areas of tobacco. In August of every year, the disease index of Alternaria spp. in the 5 growing areas of tobacco was significantly higher than that in July and reached a peak. 10% Difenoconazole water dispersible granule and 40% mycelium net wettable powder had good control effects to control Alternaria spp of more than 60% which was stable among the 5 growing areas.