Articles
BACILLUS SP. CAUSING PISTACHIO DIE-BACK IN KERMAN PROVINCE
Article number
726_112
Pages
651 – 654
Language
English
Abstract
During the 2003 and 2004 growing seasons, some pistachio trees in Kerman province showed die-back symptoms.
Initial symptoms were observed at the beginning of the growing season and they developed during two weeks after green tip stage, as shoot tips turned black and die-back.
During the growing season, the symptoms developed and vessel destruction was observed.
If these stems were not pruned during winter, die-back developed in the spring.
During the growing season, affected pistachio samples were collected and surface disinfected with 0.01% mercury chloride.
Pieces of affected vessels were grown on nutrient agar (NA) and incubated at 25°C for three to four days.
Bacterial colonies with Bacillus characteristics were isolated and 15 representative strains were selected for further characterization.
Pathogenicity of selected strains was verified on 2-3-year-old pistachio seedlings using injection of bacterial suspension (107cfu/ml) and control plants inoculated with distilled water.
Vessel destruction developed after 20 days, and a bacterium was isolated from the seedlings.
No symptoms were observed in control plants.
The strains were Gram positive, motile, with central spores and caused hypersensitivity reaction (HR) on tobacco and geranium, they were positive for anaerobic growth, nitrate reduction, VP, urease, catalase, growth at pH 5/7, NaCl 7/5 % and 45°C, acid production from arabinose, xylose, glucose and manitol, and anaerobic fermentation of glucose.
They could hydrolyzed starch, aesculin, Tween 80 and gelatin but indol production and phenylalanine deaminase were negative.
Based on the characteristics of the isolated strains, they were identified as Bacillus sp.
This is the first report of Bacillus sp. as a causal agent of pistachio die-back.
Initial symptoms were observed at the beginning of the growing season and they developed during two weeks after green tip stage, as shoot tips turned black and die-back.
During the growing season, the symptoms developed and vessel destruction was observed.
If these stems were not pruned during winter, die-back developed in the spring.
During the growing season, affected pistachio samples were collected and surface disinfected with 0.01% mercury chloride.
Pieces of affected vessels were grown on nutrient agar (NA) and incubated at 25°C for three to four days.
Bacterial colonies with Bacillus characteristics were isolated and 15 representative strains were selected for further characterization.
Pathogenicity of selected strains was verified on 2-3-year-old pistachio seedlings using injection of bacterial suspension (107cfu/ml) and control plants inoculated with distilled water.
Vessel destruction developed after 20 days, and a bacterium was isolated from the seedlings.
No symptoms were observed in control plants.
The strains were Gram positive, motile, with central spores and caused hypersensitivity reaction (HR) on tobacco and geranium, they were positive for anaerobic growth, nitrate reduction, VP, urease, catalase, growth at pH 5/7, NaCl 7/5 % and 45°C, acid production from arabinose, xylose, glucose and manitol, and anaerobic fermentation of glucose.
They could hydrolyzed starch, aesculin, Tween 80 and gelatin but indol production and phenylalanine deaminase were negative.
Based on the characteristics of the isolated strains, they were identified as Bacillus sp.
This is the first report of Bacillus sp. as a causal agent of pistachio die-back.
Authors
G. Baradaran, A. Ghasemi
Keywords
Bacillus, bacterial disease, vessel destruction, symptom.
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