Plant Disease Management Handbook

Cause Agrobacterium tumefaciens and A. rubi are the two bacterial pathogens associated with crown gall on raspberry. Both pathogens reside in soil or on plant surfaces and can infect herbaceous and woody plants from many plant families. Once present in a field they can survive for years in the soil as saprophytes.

Cause Kalmusia coniothyrium (formerly Leptosphaeria coniothyrium), a fungus that overwinters on old cane stubs and near wounds on infected fruiting canes. Cane blight may weaken fruiting canes of red raspberry. It may attack black raspberry at points where canes have been snapped off or pruned to force lateral growth. 'Boysenberry', 'Loganberry', and 'Youngberry' canes are seldom infected with cane blight unless canes first are frozen, pruned, or mechanically damaged.

Cause Seimatosporium lichenicola (formerly Sporocadus lichenicola), a fungus that can infect red and black raspberry, 'Loganberry', and Himalaya and evergreen blackberry. Blueberry can also be a host. Infection may require a previous low temperature injury of the plant but the life cycle of this fungus/disease has not been studied in detail.

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Note: Sawdust can be a source of inoculum. Mulching is more common in small plantings where plants are grown organically.

Cause Elsinoe necator, a fungus widespread in the Pacific Northwest in black and occasionally in red raspberry cultivars. All black raspberry cultivars are susceptible. The disease is not always severe enough to warrant the cost of spraying. It is particularly serious if rains continue late in spring, when spots on canes may be plentiful enough to girdle canes. Early-season infections are more severe than late-season ones.

Cause Albugo candida, a fungus-like microorganism, can cause disease on cruciferous plants including rapeseed, broccoli, cabbage, radish, and wild mustards. In the Pacific Northwest, white rust can be severe on crucifer seed crops. The pathogen overwinters as oospores in stagheads (galls formed on infected seed heads) or plant debris as well as mycelium in infected hosts. Pieces of staghorns are often found as seed contaminants and can be the primary source of infection in a field.

By C. M. Ocamb

Cause Damping-off can be caused by Pythium debaryanum, Globisporangium ultimum (formerly P. ultimum), Fusarium spp., Rhizoctonia solani, Alternaria spp., and other fungi.