Identification And Phylogeny Of The Pathogen Causing Twig Blight Of Phoebe In Zhejiang Province

Phoebe is a valuable tree species that has been loved by people since ancient times in China.It has great use value and ecological significance.In recent years,a new type of blight disease has been discovered in the Phoebe planting area of Zhejiang Province.After the branches are infected,dark brown spots appear.Swelling and cracking at the branch after the condition is aggravated.The average incidence rate in the affected area was 63.72%,and the average disease index was 29.17.Phoebe Nees and Machilus Nees species of Phoebe are found to be infected with such diseases.This research has carried out a large number of research experiments.The law and influencing factors of disease occurrence were analyzed,and the pathogenic bacteria were isolated and identified,and their biological characteristics were explored.The results provide effective theoretical guidance for the scientific prevention and control of Phoebe in the future.The results are as follows:The disease occurred sporadically in the forest from the beginning of April to mid-May,and it was a high incidence from June to the end of September.The incidence and disease index of Phoebe twig blight will also change significantly under different site conditions,including tree height,slope direction,etc.The incidence of disease and disease index of Phoebe planted on semi-sunny slope and semi-shady slope is higher than that of Phoebe planted on sunny and shady slopes.The incidence rate and the disease index of the tree age of more than 5 years are higher,and the disease is most serious in 5 to 30 years.The incidence rate and disease index of tree height above 1 m and tree height below 1 m are significant,and the disease height of 1 m to 5 m is the most serious.After separation and purification,the morphology and culture characteristics of the strains were compared and divided into two groups.The numbered JDHNY1 is the dominant species,the separation rate is 68.32%;JDHNY2 is 23.46%.Pathogenicity determination of JDHNY1,JDHNY2,JDHNY1 can cause the Phoebe twig blight.The morphology and biological identification of JDHNY1 were performed using the ITS sequence and the EF1-? sequence,and the resulting sequence was uploaded to NCBI to obtain accession numbers MK040561 and MH663527.In summary,JDHNY1 is Lasiodiplodia pseudotheobromae.The colony has the fastest colony diameter expansion rate under the treatment of glucose as a carbon source.Glucose is the optimal carbon source for Lasiodiplodia pseudotheobromae.The colony diameter expansion rate is the fastest under the treatment of ammonium sulfate as the nitrogen source.Colony diameter expansion rate on PDA medium is the fastest.The strain can also develop under the low temperature condition of 10 °C,and the optimum temperature range is 25 ?~35 ?.Lasiodiplodia pseudotheobromae is high temperature suitable bacteria.The effect of different light conditions on the development of Lasiodiplodia pseudotheobromae is not obvious.Lasiodiplodia pseudotheobromae can grow between pH 5 and 11,and the optimum pH is 5-6.This is the first report of Lasiodiplodia pseudotheobromae causing the twig blight of Phoebe.