贵州甘蔗真菌病害初步调查及褐斑病防治药剂筛选

Preliminary investigation of the fungal diseases on sugarcane in Guizhou and screening of fungicides against Cercospora longipes

为掌握贵州甘蔗真菌病害种类及发生情况,采用随机踏查、定点调查、症状诊断与病原菌形态特征观察等方法对贵州甘蔗产区7个县进行真菌病害调查;采用菌丝生长速率法,对甘蔗褐斑病进行了5种杀菌剂室内毒力测定和田间防效试验。结果表明,贵州甘蔗主要真菌病害有褐斑病、褐锈病、赤腐病、黄斑病、轮斑病、褐条病、煤烟病、黑穗病,其中褐斑病、轮斑病、褐条病发生较重,煤烟病发生严重;5种杀菌剂中,325g/L苯甲·嘧菌酯悬浮剂对甘蔗褐斑病毒力最高,防效最好,EC50为0.002 5mg/L,第3次药后10d防效达86.46%。其他4种杀菌剂对褐斑病均有较好的防治效果,可应用于甘蔗生产防治褐斑病。

In order to make clear the fungal pathogen species on sugarcane and their occurrence regularity,present situation of the fungal diseases on sugarcane was investigated by random survey,site investigation,symptomatic diagnosis and morphological observation in seven counties of Guizhou Province.Virulence of the five fungicides against Cercospora longipes Butler were also determined by mycelium growth rate method and field plot experi-ment.The results showed that the major pathogens in sugarcane-growing regions of Guizhou were C .longipes , Puccinia melanocephala H.Syd.P.Syd.,Colletotrichum falcatum Went,Mycovellosiella koepkei （W.Kr＆#252;ger） Deighton,Leptosphaeria sacchari Breda de Haan,Cochliobolus stenospilus （Drechsler）Mat.W.Yamam,Capnodi-um sp.,Ustilago scitaminea Syd.325 g/L difenoconazole · azoxystrobin SC had the highest inhibition rates against C .longipes among the five fungicides,with EC50 value of 0.002 5 mg/L,and field control efficacy was 86.46% on the 10th day after the third spraying.Other fungicides also had good control effect against C .longi-pes ,and could be applied in practice.