Pathogen Identification And Pesticides Screening Indoor Of Butterfly Orchid Diseases

Bacterial leaf spot,leaf base soft-rot caused by Pseudomonas and Alternaria spot caused by A.zinniae Pape of butterfly orchid were firstly reported in China,brown spot caused by Pseudomonas,leaf soft-rot caused by Pectobacterium of butterfly orchid were firstly reported in Jilin province,China.The sympotoms of the diseases were described in detail.Biological characteristics of the fungus and pestcide-screening indoor on the six diseases were studied.Bacterial leaf spot of Phalaenopsis,it initially appeares as water soaked spots.With the disease spread, the spots gradually turn round or elliptical,brown spot with yellow hals.When it is serious,centure of the spots turn white,even perforate,spots are rugged,hard.According to pathogenity,morphorlogy and physiological and biochemical characteristis of the pathogen and compare with parts of《Bergey's Manual of Determinative Bacteriology》9th ed and related references,it is confirmed that the disease was caused by Pseudomonas marginalis pv.phalaenopsis Gao & Liu pv.nov.Brown spot of Phalaenopsis,water-soaked spots initially appears on the leaves.Gradually turn irregular, white and hollow.Areas arround the spots turn yellow.According to pathogenity,morphorlogy and physiological and biochemical characteristis of the pathogen and compare with parts of《Bergey's Manual of Determinative Bacteriology》9th ed and related references,it is confirmed that the disease was caused by Pseudomonas cattleyae(Pavarino 1911)Savulescu 1947.Soft-rotl of Phalaenopsis,water-soaked light brown lession occurs in the base of the leaves.Gra dually turn to deep brown.When it is serious,leaves droop because losing the holding power.Final ly,wilt and fall off.According to pathogenity,morphorlogy and physiological and biochemical chara cteristis of the pathogen and compare with parts of《Bergey's Manual of Determinative Bacteriolog y》9th ed and related references,it is confirmed that the disease was caused by Pseudomonas ma rginalis pv.pastinacae(Burkholder 1960) Young et al.1978.Soft-rot2 of Phalaenopsis,round spots with ring initially appeares on leaves,with the disease de velop,ring spots disappear,and many of the spots combine to a big water-soaked lessions with not clear borders.Although the diseased leaves are complete,the upper and lower surface of leaves have separated from rotted inner tissues.Eventually the whole leaf fall off.According to pathogenity,morp horlogy and physiological and biochemical characteristis of the pathogen and compare with parts of《Bergey's Manual of Systematic Bacteriology》2nd ed and related references,it is confirmed that the disease was caused by Pectobacterium carotovora subsp.carotovora(Jones 1901) Bergey et al.1923.Soft-rot3 of Phalaenopsis,the symptom is the same as soft-rotting2 of Phalaenopsis.According to pathogenity,morphorlogy and physiological and biochemical characteristis of the pathogen and compare with parts of《Bergey's Manual of Systematic Bacteriology》2nd ed and related references,it is confirmed that the disease was caused by Pectobacterium chrysanthemi pv.paradisiaca(Victoria et Barros) Dickey et Victoria 1980.Alternaria spot of Phalaenopsis,a small,water-soaked black spot occurs on leaves at first,gradu ally formed pitted spot with clear borders.The conidiophore deep brown color,extend by sy mpode.Conidia with 1-4 cramsverse septu(most 2-3) and 0-3 longitudinal or oblique sep tu(most 1-2).150-200μm×15-20μm.Short rostra,olive color.The pathogen was identified as A. zinniae Pape.Pestcides are screeded for all of the diseases with methods of inhabition zone indoor.The result s showed that the inhabtion effect of Streptomycin sulfate,Oxytetracycline,Tetracycline,Erythromycin are the best to all of pathogenic bactericide.Polyoxin,thiram,mancozeb,score are the best to Alter naria spot of Phalaenopsis.They are the preferred bactericides for further field trial.