Identification Of The Causal Organism Of Stalk Rot On Hylocereus Undulatus Britt And Bactericide Screening Indoor

Dragon fruit stalk rot pathogen infestation fleshy stems,symptoms of yellow dragon fruit stems partially rotten meat portion is broken,only the remaining central woody stem pith of rotting parts gradually spread to the ends of the stems,serious decaying woody parts of hip fracture will,at the junction of healthy clearly obvious.After stem rot the stems of flowers,the result is not significantly less than the number of infected healthy stem,causing the dragon fruit growing areas of production,there is no cause Hainan dragon fruit stalk rot pathogen identification and related research reports.This is the first reported dragon fruit stalk rot in Hainan province,the detailed description of the symptoms of the disease and damages,and get sick from three strains of dragon fruit stems separated,respectively,is a bacterial strain QH-G,QZ-G,fungal strains DZ-F.Caused by bacteria named dragon fruit stem rot bacterial stalk rot,caused by fungus named dragon fruit stem rot fungal stalk rot.Two bacterial strains pathogenic measured,and then were morphological observation,traits,physiological and biochemical characteristics measured,host range determination,16S rDNA sequence analysis,phylogenetic tree to determine its classification home culture.According to morphological analysis results and the physiological and biochemical test measurement results,two strains were gram-positive bacteria(G +),anaerobic growth on nutrient agar did not produce pigment,catalase positive,physiological and biochemical test results show that,two strains at 37 ℃,2%NaCl can grow,can degrade pectin,can hydrolyze starch,cellulose,can reduce nitrate,but can not produce indole,not hydrolyze urea,egg yolk lecithin and Tween 80.Can utilize glucose,D-glucose,L-arabinose,mannitol,D-xylose,glycerol and raffinose and acid production,but not the use of L-rhamnose,inulin,sorbitol,D-fructose,cellobiose,sweet,sorbitol.Sodium benzoate can use,but could not use sodium citrate,sodium succinate and sodium tartrate.16S rDNA sequence analysis showed that:two strains with the highest sequence similarity is Paenibacillus polymyxa,homology of 97%or more.According to the phylogenetic tree situation,combined with the results of morphological identification,physiological and biochemical test results,see "System identification of common bacteria Handbook",the two strains identified as Paenibacillus polymyxa(Paenibacillus polymyxa).Meanwhile,the fungal strain was pathogenic measured separately after morphological observation,host range determination,ITS sequence analysis,phylogenetic trees,clear classification home.According to the morphological identification results combined with molecular biology,the fungal strain was identified as a new dark column sylviforme(Neoscytalidium dimidiatum).Inhibition zone method,10 kinds of bactericides on Pitaya bacterial stalk rot pathogen virulence were measured.The results showed that:45%Dyson ammonium agent best control effect,the maximum inhibition zone;50%thiram WP somewhat less,the linear regression equation was y = 2.380 + 2.477x and y = 2.896 + 1.146x,ECso were 0.4929 and 0.0240.72%agricultural streptomycin sulfate soluble powder effect,followed by the linear regression equation y = 1.020 + 1.040x,EC50 value of 2.5686.These three agents as pitaya bacterial stalk rot in the field efficacy trials of the drug of choice.