Sensitivity To 5 Fungicides Of Botrytis Cinerea Of Tobacco And Screening On Fungicides To The Pathogens In Fujian Province

Tobacco gray mold is one of the most important diseases of tobacco in Fujian Province,especially in Sanming tobacco growing area.In this paper,the pathogens of Botrytis cinerea in main tobacco growing areas in Sanming,Fujian province were isolated and identified,resistance to five fungicides was monitored and fungicides were screened on controlling the tobacco gray mold disease,the following results are obtained:(1)30 strains B.cinerea were isolated which the samples collected from Thaining,Jianning,Yong'an,Shaxian,Qingliu and Datian tobacco fields by using tissue isolation method,and were identified as B.cinerea based on the morphological and molecular characteristics(ITS region sequence analysis),and the pathogenicity was verified in pot conditions.(2)Resistance to five fungicides,pyraclostrobin+metiram,iprodione,pyrimethanil,boscalid and procymidone was monitored by the method of mycelium growth rate method(MIC method).Results shows that strains of Botrytis cinerea in Fujian Sanming tobacco area had a more serious drug resistance to pyrimethanil,and high resistance frequency of the agent;higher concentration fungicides iprodione and procymidone had certain inhibition effect on Botrytis cinerea,but the strains also showed obvious resistance to the two fungicides.Botrytis cinerea in Sanming tobacco had relatively low resistance to fungicides pyraclostrobin + metiram and boscalid.(3)The field trials were conducted in three areas of Taining,Mingxi and Yong' an to study the effects of five fungicides on the control of tobacco gray mold diseases.The results shows that:in Taining,four fungicides,pyraclostrobin metiram,iprodione,procymidone and boscalid had a good control effect on tobacco gray mold diseases,maximum effectiveness was 52.26%;but during the experiments,it was found that a higher concentration fungicides procymidone and iprodione could affect the growth of some tobacco plants.In Mingxi fields,pyraclostrobin metiram and boscalid were showing good control effect on the diseases,and the other three kinds of pesticides had poor control effect and the results were vulnerable to climate conditions.In Yong'an's,fungicides pyrimethanil,procymidone and boscalid were showing good control effect on the dieases,and after fifth application,the maximum effectiveness were 88.06%,91.04%and 89.39%respectively,but the control effect of iprodione on tobacco gray mold diseases was poor,after fifth,the effectiveness was only 39.14%.Based on the above results,intensive monitoring of resistance in heavy tobacco gray disease areas is needed and this is the good way to guide the scientifically use fungicides to control the tobacco gray mold diseases.