Crown Gall and Cane Gall in the Home Fruit Planting

Cane gall occurs on brambles and many other crops, with all type of brambles being susceptible to infection. The impact of the disease on plant growth and production can range from no apparent effect to the death of the plant. Only grass-like plants are not affected by crown gall. 

Symptoms

Crown and cane gall is characterized by the spongy, rough, pinhead- to golf ball-sized, tumor-like swellings that become brown, woody knots with age. Galls may appear in the crown area or on the canes, first as light-colored knobby growths, and later turn brown and then almost black. More intense gall formation seems to occur in years with higher incidence of winter injury. With severe infection, vigor may be decreased,  and few new canes may be produced. Weakened canes are broken easily by the wind and are more susceptible to winter injury. The plants might show water stress and nutrient deficiency symptoms since the movement of water and nutrients throughout the plant is disrupted. Varieties differ in susceptibility.

Disease Cycle

This disease is caused by the soilborne bacteria Agrobacterium tumifaciens and Agrobacterium rubi.   Plants are infected through wounds that can result from natural causes (e.g., insect feeding, frost damage, nematode feeding) or from mechanical damage (e.g., pruning, cultivating, harvesting). The bacteria overwinter in the soil and in galls. Bacteria are then spread by splashing rain, running water, cultivation, and pruning from soil and infected plants. As the galls enlarge, the soil can become heavily infested and will remain so for many years.

Disease Management

The best control measure is prevention. Plant only certified, disease-free nursery stock, and take care not to wound the plants, especially the root systems, at planting time. Try to plant only in sites with no history of disease, or wait at least 3 to 5 years before replanting. If a diseased plant is detected, remove and burn the roots and tops of the plant. Dispose of the soil surrounding the roots of the affected plant. No chemical control is known.