Identification And Basic Research Of Blueberry New Diseases Caused By Pestalotiopsis Kenyana

Pestalotiopsis-like fungi is one of the most important pathogens of blueberry.With more and more attention paid to functional fruits,blueberry industry develops more and more rapidly.At present,large-scale cultivation of blueberry has been carried out in 27 provinces in China.Blueberry branch blight and leaf spot caused by Pestalotiopsis-like fungi occur more common than before,which seriously decrease the economic benefits of blueberry industry.Based on our previous research,the Pestalotiopsis-like fungi that we failed in identifying before has been chosen for this study.We augmented the model strains for further research and reconstructed phylogenetic analysis combined ITS,?-tubulin,and tef1 gene.Combined with the morphological characteristcs,we found a new record species of Pestalotiopsis-like which can damage blueberry.Furthermore,we screened ISSR primers which could be used for analyzing diversity of fungi,conducted efficacy experiments of 5 fungicides to 3 new recorded species of Pestalotiopsis-like fungi and evaluated resistance of 8 main blueberry varieties to the Pestalotiopsis-like isolates which caused branch blight.Main results are shown below:1.A new record species was identified as Pestalotiopsis kenyanaThere were 40 unidentified strains from 11 provinces in China,including 7 strains obtained from leaves and 33 strains from stems.The newly added model strains: the genus Pestalotiopsis added 8 novel species,the genus Pseudopestalotiopsis had 5 new species,and the genus Neopestalotiopsis added 2 novel species.Based on the molecular phylogenetic analysis of ITS,?-tubulin and tef1,9 tested strain including YN06 F were clustered with the same clade as the model strain.However,the other tested strains have not been clustered with any new model species,which needs to do further study.The morphology of YN06 F,which was a candidate new record species,was observed.The colony of YN06 F is white.At the later stage of growth,black and sparse sporocarp occured,which often released black ink like conidium angle.The conidia were measured(20.7-28.8 ?m)×(4.7-7.2)?m,with 2-3 apical appendages,10.3-20.5 ?m in length,basal appendages 3.5-7.0 ?m in length,and medium cells 13.2-18.0 ?m in length.The morphological characteristics of this strain are consistent with species of Pestalotiopsis kenyana.Combined with morphological identification and phylogenetic analysis,a new record species pathogen of blueberry was identified as P.kenyana.2.Three ISSR primers were screened for the analysis of Pestalotiopsis-like fungiAccording to the branches of the phylogenetic tree in this study,the representative strains were selected from each branch to make the different DNA mixing pool.On this basis,three primers(810,864,891)were screened from the primers published by Columbia University,which can be used for the further study of diversity.3.The virlunce of different fungicides on Pestalotiopsis-like fungi of blueberry was determinedIn this study,three strains,P.kenyana(YN06F),P.trachicarpicola(GX02A)and N.chrysea(FZXM038-b),were used as targets.The virlunce experiments in vivo of five fungicides(Fludioxonil,Iminoctadine trialbesilate,Pyraclostrobin,Thiophanate-methyl and Iprodione)on three fungi were determined.The results showed that the five fungicides performed well,the maximum EC50 value was 3.0883 ?g/ml(Iprodione).The efficacy of Fludioxonil was the best among five fungicides,and it's maximum EC50 value was 0.0561?g/ml..The sensitivity of the three target strains to the five fungicides is similarly,so it is not necessary to treat them differently.4.Determination of resistance of different blueberry varieties to Pestalotiopsis-like fungiIn this study,the newly recorded species P.kenyana(YN06F)and previously identified strains N.chrysea(FXZM038-b)and Neopestalotiopsis sp.(SCCD01C-b)were used as the target pathogen to evaluate the resistance of 8 main blueberry varieties: Duke,Bluecrop,Eliott,Brigitta,O'neal,Sharpblue,Legacy and Misty.Our findings suggested that different target fungi had different pathogenecity to different blueberry varieties.All of the 8 varieties had strong resistance to P.kenyana.Seven varieties had strong resistance to N.chrysea,and another one(Bluecrop)had weak resistance to N.chrysea.Six varieties had strong resistance to Neopestaltoiopsis sp.(SCCD01Cb),and the rest two varieties(O'Neill and Duke)had weak resistance.The size of the disease spots reached 89.5 mm 7 days post inoculated on O'Neill and 56.1 mm on Duke.It is necessary to strengthen the prevention and control of the disease when planting Lanfeng,O'Neill and Duke.