Articles
BACTERIAL CANE BLIGHT OF ROSE CAUSED BY PSEUDOMONAS SYRINGAE
Article number
870_12
Pages
109 – 114
Language
English
Abstract
A disease affecting rose (Rosa spp.) plants with symptoms of cane blight has been observed in southwest Idaho USA, since 1996. The symptoms were commonly observed under cool, wet conditions during spring (March to May) on several cultivars of climbing, floribunda, grandiflora, hybrid tea, hybrid perpetual, miniature and shrub roses.
The symptoms usually started at the base of a vegetative bud or at leaf scars or wounds, as reddish brown areas on the bark that later turn dark purple to black and necrotic.
The necrotic areas expanded around and along the cane, often involving a major part or even the entire cane.
Vegetative buds on the affected parts of the cane turned brown and dried.
The surface of the necrotic areas of the bark was glossy, and the tissue beneath the epidermis was brown to dark brown, and moist in the early stages.
Microscopic examination of the necrotic tissue revealed profuse bacterial streaming, and isolations on Kings B agar plates consistently yielded creamy, whitish-gray, raised colonies that produced a diffusible pigment which fluoresced blue-green under ultraviolet light.
Pure cultures were characterized using standard bacteriological tests, including Gram staining, LOPAT tests, Biolog, cellular fatty acid analysis, and inoculation to lemon and cherry fruits.
Pathogenicity of the isolated bacterium to rose shoots and canes was confirmed by inoculations, and the bacterium was re-isolated from the symptomatic tissue and characterized.
Based on the bacteriological characteristics and pathogenicity, the bacterium causing cane blight of roses was identified as an undetermined pathovar of Pseudomonas syringae. The bacterial cane blight disease described here is distinctly different from the various symptoms on roses previously attributed to P. syringae and/or P. syringae pv. morsprunorum in the literature.
Some of the rose cultivars that showed severe symptoms of bacterial cane blight under conditions of natural incidence are listed.
The symptoms usually started at the base of a vegetative bud or at leaf scars or wounds, as reddish brown areas on the bark that later turn dark purple to black and necrotic.
The necrotic areas expanded around and along the cane, often involving a major part or even the entire cane.
Vegetative buds on the affected parts of the cane turned brown and dried.
The surface of the necrotic areas of the bark was glossy, and the tissue beneath the epidermis was brown to dark brown, and moist in the early stages.
Microscopic examination of the necrotic tissue revealed profuse bacterial streaming, and isolations on Kings B agar plates consistently yielded creamy, whitish-gray, raised colonies that produced a diffusible pigment which fluoresced blue-green under ultraviolet light.
Pure cultures were characterized using standard bacteriological tests, including Gram staining, LOPAT tests, Biolog, cellular fatty acid analysis, and inoculation to lemon and cherry fruits.
Pathogenicity of the isolated bacterium to rose shoots and canes was confirmed by inoculations, and the bacterium was re-isolated from the symptomatic tissue and characterized.
Based on the bacteriological characteristics and pathogenicity, the bacterium causing cane blight of roses was identified as an undetermined pathovar of Pseudomonas syringae. The bacterial cane blight disease described here is distinctly different from the various symptoms on roses previously attributed to P. syringae and/or P. syringae pv. morsprunorum in the literature.
Some of the rose cultivars that showed severe symptoms of bacterial cane blight under conditions of natural incidence are listed.
Authors
S.K. Mohan, V.P. Bijman
Keywords
Rosa spp., bacterial disease, symptoms, bacterial pathogen, pathovar, winter damage, cold damage, cultivars
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