Studies on Die-back of Pine and Its Pathogen(I)

The die-back of pines caused by Sphaeropsis sapinca (Fr.) Dyko & Sutton widely spread in Jiangsu Province.Pine stands were infected severely in many farms and several hundred ha of pine stands were killed.It is one of the most serious forest diseases in China.Among those pines,P.taeda and P.elliottii are infected severely,P.thunbcrgii is also severely infected sometimes.P.massoniana is more resistant.The most prominent symptoms of the diease are die-back,necrosis of buds and base of the two year’s needles in Jiangsu Province.Morphology,culture characteristics,germination characteristics,sporogenous capacity,pathogenicity of the isolates from Jiangsu,Fujian and Heilongjiang Province were compared,and no difference was found among them.The pathogen of die-back of pine produced abundant sporocarps on steam sterilized needles under black light within two weeks.The temperature range for conidia germination is 5~35℃ and the optimun temperature 25℃.Spore germination needs 1% sugar solution or needle juice.Spore germination is no so good in water because air is too little in water.The pH range for myceliae growth is pH 4~10 and the optimum pH 6.Sphaeropsis sapinea is capable of utilizing para-gine as nitrogen source but is not capable of utilizing urinate.