Location: Southern Horticultural Research
Title: Botryosphaeria Cane Canker Author
Submitted to: Compendium of Blackberry and Raspberry Diseases and Insects
Publication Type: Book / Chapter
Publication Acceptance Date: November 18, 2009
Publication Date: N/A
Technical Abstract: One of the more serious cane canker diseases of thornless blackberry plants in the eastern U.S. is caused by Botryosphaeria dothidea. Cane canker disease is highly destructive, often killing canes and reducing fruit yields to uneconomic levels. Cankers generally develop around one or more buds on the main stem of the second year floricanes and appear as reddish to dark reddish brown discolorations below or to one side of the subtending leaf petiole. The bud or lateral shoot at the infected node is usually killed. Developing cankers have a zonate pattern of dark and lighter coloration, and old ones become light-colored (to silvery gray) on dead canes. Well-developed cankers split open longitudinally, exposing the pith. Symptoms similar to Botryosphaeria cane canker may also be caused by other fungi, winter freeze damage, or crown borer infestations. Young lesions on canes have been found throughout the growing season, indicating that infection may take place any time from early spring to fall. The fungus can overwinter in cankers in dead canes and probably also in cankers on living primocanes. Once B. dothidea becomes established in a blackberry planting, the biennial growth habit of blackberry plants ensures perpetuation of the fungus. After the pathogen is established saprophytically in senescent leaf petioles, it can invade adjacent healthy cane and bud tissue. Cultivars with a high incidence of disease often tend to retain a high percentage of petioles into midwinter. The primary control is to establish new plantings with disease-free nursery stock. B. dothidea is a common pathogen of other fruit crops; therefore, proximity to these potential sources of inoculum should be considered when establishing new plantings. Plantings should be fertilized to maintain plant vigor, but the use of excessive fertilizer, especially nitrogen, should be avoided. Fungicide control measures have not been established for this disease. Some resistance in thornless blackberry cultivars has been noted in field plot studies.