Magazine article Sunset

Crown Gall - a Root Swelling That Enfeebles Plants

Magazine article Sunset

Crown Gall - a Root Swelling That Enfeebles Plants

Article excerpt

Crown gall--a root swelling that enfeebles plants

Often lethal, always enfeebling, crown gall can occur wherever plants are grown. The disease is caused by a soil-dwelling microbe called Agrobacterium tumefaciens; it enters plant tissue through any sort of wound. Infection results in swellings (galls) on roots, or on the crown where trunk and roots join.

While galls on plant crowns are visible (as shown above right), you can't be certain whether galls are growing on roots unless you dig up the plant (above left). Often the only sign that a plant is infected is feeble growth or actual decline.

Galls are woody at first, later spongy or corky in appearance. They can become pea-size to basketaball-size, interfering with the transfer of nutrients. Most garden plants are susceptible, including most deciduous fruit trees and other members of the rose family.

Don't confuse crown gall with clumsy graft unions, which may make swellings but don't show notable changes in color or texture. Root nematode damage can also resemble crown gall, but the swellings are usually smaller and more numerous.

Prevent its spread. Galls often appear at the point where grafting or budding is done--and the disease is frequently transmitted by tainted tools. …

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