Identification,characteristics And Fungicide Screening Of Pathogens On Phoebe Bournei

Phoebe bournei,is an important timber tree species.The phoebe wood is used extensively in the construction and furnishings because of its aroma and tenacity.So P.bournei was listed as the national rare and endangered species of China.There were large artificial forests of Phoebe bournei in Fujianprovence.However,the artificial forests have low biodiversity and poor stability of stand structure,the disease of P.bournei frequently occurs.In view of this,the Phoebe leaf spot and Phoebe canker were selected for plant pathogen isolation and identification.The biological characteristics of two plant pathogens,the screening of fungicide and plant extract for inhibiting the pathogens were studied.The results are as follows:1.Identification and biological determination of pathogenic bacteriaPhoebe leaf spot:The Koch's Postulates was used to isolate the pathogen,and the pathogen was identified by morphological observation and BLASTITS sequence in NCBI.The pathogen was identified as Pestalotiopsis microspore.The results showed that 28 ? at dark and pH 5.0 were the best condition for P.microspore mycelia growth on Czapek-Dox Medium.And 28 ? at dark,pH 8.0 were the optimum condition for conidia sporulation on PDA.In the assay of usage of,mycelia could grow fastest in glucose and peptone were the best carbon and nitrogen sources for P.microspore growth,respectively.The mycelia and conidia lethal temperature were 50 ? and 60 ?,respectively.Phoebe canker:The pathogen was identified as a Bionectria ochroleuca by morphological assays and the alignment of ITS sequence.The results of biological characteristics showed that 25 ? at dark and pH 6.0 were the best condition for mycelia growth while cultured on PDA medium plus phoebe extract.,The color of colony was changed to orange under the light.,mycelia can grow fastest in maltose and potassium nitrate,respectively.25 ? at dark and pH 7.0 were the optimum condition for sporulation on PDA medium.The lethal temperature of mycelium and conidial was 55 ? and 65 ?,respectively.2.toxicity measurementPestalotiopsis microspore:The results of screening showed that,Cao's thiophanate,trimanin and hymexazol could inhibit P.microspore growth significantly,and the EC50 were 0.12 ?g·mL-1,0.68 ?g·L-1 and 27.1?g mL-1,respectively.Cao's thiophanate and trimanin had good inhibitory effect on conidia germination.The result suggested that Cao's thiophanate and trimanin should be used for controlling Phoebe leaf spot.Bionectria ochroleuca:The results showed that,inhibitory effect of ShiGao and Cao's thiophanate was significant,And the EC50 were 0.32?g·mL-1 and 1.16 ?g·mL-1,respectively.ShiGao had the best inhibitory on conidia germination.And it is recommended to use as the field control fungicide.3.Determination of bacteriostasis of plant extractsPestalotiopsis microspore:The results showed that the extract of Phellodendron,Coptis,Anemarrhena and Polygala tenuifolia had significantantimicrobial activities.And the inhibitory rates were 84.13%,68.65%,63.48%and 52.58%,respectively.Coptis and Phellodendron had better effects on the inhibition of conidia germination.Bionectria ochroleuca:The results showed that the Phellodendron,Coptis and Anemarrhena had significant effects on antimicrobial activities.And the inhibition rates were 80.73%,54.55%and 50.10%,respectively.Among them,the Anemarrhena had the best effect on the inhibition of conidia germination.