STUDY ON THE DIEBACK OF CEDAR CAUSED BY BOTRYTIS LATEBRICOLA JAAP.

The dieback of Cedar,Cedrus deodara (Roxb.) Lond,was first found in May 1986 in Hangzhou,Fuyang and Linan,Zhejiang province.It caused the death of needles in bunch and tender spring shoots in great quantity.The results of investigation on 11 standard plots showed an average incidence of 82.2% (31.8-100.0%) and disease index of 27.0 (7.9-52.2).The pathogen has been examined through Koch's postulates and identified as Botrytis latebricola Jaap.,a fungus thus with new record in China.The temperature and relative humidity range for spore germination of the pathogen are 10-30℃ and90% respectively with the optimum temperature between 20-25℃.The pH value for spore germination is 3-10 with the optimum of 4-5.The disease control effect reached 35.0-46.7% when sprayed 0.14% wet table thiophanate methyl suspension 2-3 times in May.