Diversity And Fungicide Screening Of Strawberry Botrytis Cinerea In Sichuan Province

Strawberry gray mould is a fungal disease caused by Botrytis cinerea,which occurs in its production,transportation and storage and cause great losses.195 of B.cinerea strains from ten counties or cities in Sichuan Province were studied on the colony type,growth rate,virulence of isolated strawberry leaves,and resistance levels to pyrimethanil,iprodione,and fluomycetes and so on.The genetic polymorphism of isolated trains was also analyzed with ISSR molecular marker technique.The new synergist preparations were screened and processed in our experiment.The results showed that:1.There was a slight difference in the colony type,growth rate and virulence among the strains from different regions,and was also no significant correlation between the colony type and growth rate.The type of B spore had the strongest pathogenicity on the isolated strawberry leaves,and there was no correlation between the mycelial growth rate and the pathogenicity at the P=0.05 level.2.The genetic polymorphic of strains from different regions in Sichuan Province was abundant,and 61 polymorphic loci(96.83%)were achieved with 6 ISSR primers.The indexes of Nei's gene diversity(H)and Shannon information were 0.2942 and 0.4511,respectively.The average of genetic diversity(Ht)index was 0.2976,which in the strains(Hs=0.2458)was much higher than that in geographical distribution species(Dst=0.0518).The average of genetic similarity coefficient(Gst)and gene flow(Nm)achieved 0.1742 and 2.3696,which indicated that the genetic diversity of B.cinerea among populations was not obvious,and the gene communication in the populations was frequent.The strains of B.cinerea from ten main districts of strawberry in Sichuan Province could be divided into 3 groups via the method of UPGMA.The strains collected from Jiangyou were clustered in the first group,followed by the Chongzhou and Guanghan strains in the second group,and the other strains were belonged to the third group.The results revealed the genetic structure and gene flow direction of B.cinerea of strawberry occurred in Sichuan Province.3.The resistance frequencies of isolated strains to pyrimethanil,iprodione,fludioxonil and fenhexamid were assayed using the lowest concentration inhibition method,which were 92.3%,66.7%,32.8% and 7.1%,respectively.Meanwhile,the strains producing high resistance on fludioxonil reached 4.32% and no high resistant strains on fenhexamid was found.4.The joint toxicity of ludioxonil and polyoxin showed that the strongest synergist ratio was 7.5 to 1 with the co-toxicity coefficient(CTC)of 226.5.Then the synergist ratio was further processed and 30% fluocinilone·polyoxin aqueous suspension meeting with all government standards was achieved through the auxiliary screening and formulation optimization.The efficacy was further worthy of research in pot and field trail to control strawberry gray mold.