Northwest berry Foundation

Management Detail

Crown and Cane Gall

in Blackberries

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Latin name: Agrobacterium tumefaciens and A. rubi

Description:

Reason for Concern:
1) Serious threat to susceptible blackberry variety production.
2) Root infections may go undetected until galls are so numerous that plant vigor is affected.
3) With infected plant stock, yield can be significantly reduced, but susceptibility varies by variety.
4) Infected plants show stunting as galls interfere with water and nutrient flow.

Identification/Symptoms:
Spongy, rough, tumor-like swellings that age into brown, woody knots ranging from pinhead to tennis ball size. Crown galls develop in spring on roots and plant crowns and as whitish eruptions on fruiting canes in spring/summer. Eruptions later turn brown to black. Some disintegrate over time, while others remain for the life of the plant. Galls can cause canes to split open, or cause the production of dry, seedy berries, and stunt growth of new canes. Plants may show water stress and nutrient deficiency symptoms because nutrient movement throughout the plant is disrupted. If infection is not severe, tops of infected plants may appear normal. Symptoms may not develop for over a year if infection occurs when temperatures are below 59F. The fruiting canes produce short, weak laterals, leaves turn yellow and dry at the edges, curling up at the onset of warm weather. Root systems from these dying plants can resemble a string of beads (galls).

Disease Cycle:
Crown and cane gall are caused by soil-borne bacteria that infect the plant through wounds only, which can result from lateral root formation, leaf scars and winter injury or from mechanical causes (pruning, cultivation, harvesting, insect feeding). The bacteria overwinter in the soil and galls are spread by splashing rain, running water, cultivation, and pruning from soil and infected plants. Heavily infested soil will remain infested for many years. Inoculum remains in the ground for a very long time after infected plants are removed and the bacteria survive almost indefinitely in decaying root galls or in alternate hosts.

Links:

Scouting:

  • Carefully check planting stock for the presence of galls.
  • In existing plantings, look near the crown for evidence of galls, or dig plants up to examine roots for galls.

     
    Cultural Controls:

    • Plant certified nursery stock or tissue culture plants. If this technique is utilized, plant into fumigated soil to minimize likelihood of infection.
    • Inspect planting stock carefully for evidence of gall.
    • Take care not to injure plants when planting to prevent sources of infection.
    • Avoid susceptible varieties.

     

    For information about chemical controls, check with our Pesticide Guide.

    images


    photo by T. Peerbolt


    photo by T. Peerbolt


    photo by T. Peerbolt

     

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    Northwest Berry Foundation

    Northwest Berry Foundation

    © 2016

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