Crown Gall
Caused by tumor-inciting bacteria Pseudomonas tumefaciens present either in the soil or on root cuttings
Crown gall disease is caused by tumor-inciting bacteria Pseudomonas tumefaciens present either in the soil at planting time or on propagative root cuttings.
The disease can be recognized by the presence of galls or tumors on the roots or on the crowns either below or just above the soil line. Galls may range from pea-size or smaller up to several inches in diameter. Plants may be stunted or weakened by crown gall bacteria. This makes them susceptible to invasion by other soil organisms.
The galls at first ate small, light green, and soft. Later they become very large, hard, and turn to a dark brown color. They may be distributed over the entire root system, and in badly diseased plants are found even on the smaller branches several feet from the ground. The galls which occur above ground are usually smaller than those underground. As the galls become older, they become rough and friable, so that when disturbed they may break up into numerous small segments.
If plants are purchased from the nursery, they should be carefully inspected to see that there is no evidence of crown gall on the roots. It is best to secure plants from a nearby plantation where the parent plants may also be examined. No plant from a galled parent plant should be used even there is no evidence of disease on the roots. If possible, a site for a new plantation should be selected which has not been in plants for a number of years. After the plantation is established, care should be taken to avoid injuring the roots. This can be done by practicing shallow plowing and hoeing. Heavy mulching with straw has been found to prolong the productive life of a plantation where crown gall was prevalent.
The disease can be recognized by the presence of galls or tumors on the roots or on the crowns either below or just above the soil line. Galls may range from pea-size or smaller up to several inches in diameter. Plants may be stunted or weakened by crown gall bacteria. This makes them susceptible to invasion by other soil organisms.
The galls at first ate small, light green, and soft. Later they become very large, hard, and turn to a dark brown color. They may be distributed over the entire root system, and in badly diseased plants are found even on the smaller branches several feet from the ground. The galls which occur above ground are usually smaller than those underground. As the galls become older, they become rough and friable, so that when disturbed they may break up into numerous small segments.
If plants are purchased from the nursery, they should be carefully inspected to see that there is no evidence of crown gall on the roots. It is best to secure plants from a nearby plantation where the parent plants may also be examined. No plant from a galled parent plant should be used even there is no evidence of disease on the roots. If possible, a site for a new plantation should be selected which has not been in plants for a number of years. After the plantation is established, care should be taken to avoid injuring the roots. This can be done by practicing shallow plowing and hoeing. Heavy mulching with straw has been found to prolong the productive life of a plantation where crown gall was prevalent.
