Identification,Biological Characteristics And Fungicide Screening Of 3 Fungal Pathogens From Kiwifruit In Fengxi County

Kiwifruit?Actinidia chinensis Planch?is an important and characteristic fruit tree in Fengxin County,Jiangxi Province.The development of kiwifruit production plays an important role in promoting the county's economic development and drive farmers to become rich.However,With the growing scale of kiwifruit planting in this county,the occurrence of diseases is increasing and the degree of damage is worsening.In recent years,3 fungal diseases of black spot,White streak feather and black mould of Kiwifruit have appeared in Fengxin county.Identification,biological characteristics test and fungicide screening of their pathogens were carried out.Objective of this research is to ascertain the causes of these diseases and lay a foundation for the study of disease occurrence regularity and their control.The results were as follows:?1?Pathogens of three fungal diseases were identified by isolation of pathogen,culture characteristics,morphological observation and techniques of molecular biology.It was showed that pathogen of kiwifruit black spot was Alternaria alternata,pathogen of kiwifruit white streak was R.necatrix and pathogen of kiwifruit black mould was Pseudocercospora actinidiae.?2?Among the biological characteristics,OMA medium is the most suitable medium for the growth of A.alternata mycelia.The best carbon and nitrogen sources are maltose and beef extract respectively.It can grow in the range of 5³5?and the most suitable temperature and pH value were 25?and 6 respectively.The optimum medium for the growth of R.necatrix mycelium is NA medium.The optimum carbon and nitrogen sources were grape carbon and beef extract,respectively.The most suitable temperature was 25?and 7 was the optimum pH for its growth.Illumination was not conducive to the growth of R.necatrix mycelium.OMA medium was the optimum medium for growth of P.actinidiae mycelium,and the optimum carbon and nitrogen sources were Yeast powder and peptone respectively.The range of temperature for growth of P.actinidiae was 5³0?and 25?was the optimum temperature.The high temperature above 35?was not conducive to the growth of P.actinidiae mycelium.The optimum pH range for the growth of the strain was pH 2⁷.Light had no significant effect on the growth of the strain.?3?In indoor toxicity test of fungicides to A.alternata,eight fungicides including 10%schizandromycin,50%prochloraz manganese salt,25%hexazole,75%trifloxystrobin·tebuconazole,25%propiconazole,10%difenoconazole,75%tebuconazole pyrimether and 40%fluorosiloxane were highly toxic to A.alternata,with EC₅₀0 values ranging from 0.1821 to 0.7633 ug/ml.In the toxicity test to R.necatrix,thirteen pesticide including 10%shenqinmycin,22.5%pyrimidine,50%prochloraz manganese salt,45%sodium dichlorosulfonate,50%carbendazim,25%propiconazole,25%pyrimethyl ester,70%thiophanate-methyl,10%polyantimycin,40%pentachloronitrobenzene,30%Carbendazim,40%fluorosilazole and 0.3%tetramycin were all highly toxic to R.necatrix,and the EC₅₀0 values ranged from 0.0001 to 0.6861 ug/ml.