Biological Characteristics and Screening of Fungici des for Lasiodiplodia theobromae Associated with Cinnamomum camphora Twig Blight

Cinnamomum camphora is a multipurpose native tree species resource in China,with great economic and ecological value.Twig blight was a newly found branch disease in recent years,which seriously affected the healthy and sustainable development of C.camphora plantation.For the purpose of clarifying the biological characteristics and screening effective fungicides for field disease control experiment,biological characteristics of strain Lasiodiplodia theobromae JY-6 and effects of fungicides were taken in the laboratory of Forest Protection Research Institute of Fujian Agriculture and Forestry University in 2020—2021.The optimal conditions for mycelium growth of strain JY-6 were potato dextrose agar (pH 5.0) cultivated at 30 ℃ with all-day illumination,while conidium germination was optimal on potato dextrose agar medium (pH 6.0~7.0) at 30 ℃.The optimal carbon sources for mycelium growth and conidium germination were saccharose and glucose,respectively,while the suitable nitrogen source for both was ammonium nitrate.Conidium germination had a positively correlation with relative humidity,but wasn’t significantly affected by illumination conditions.Fungicides such as Metalaxyl-M fludioxonil,Carbendazim,Pyrazole methionine,metriaxyl,Flusilazole and Tebuconazole that chosen,with EC₅₀ and EC₉₀ between 0~0.1 mg·L^-1 and 0~5 mg·L^-1 respectively,had obvious inhibitory effect on strain JY-6 indoor,especially Metalaxyl-M fludioxonil(EC₅₀=0.008 mg·L^-1,EC₉₀=0.058 mg·L^-1).In this study,biological characteristics of strain JY-6 were clarified,and fungicides with better inhibitory effect were screening,which would lay a foundation for the monitoring,prediction and fungicides screening outdoor of this disease.