Crops
Agrobacterium tumefasciens (Bacterial neck tumor)
Agrobacterium tumefaciens is a bacterium widely distributed in the world and responsible for tumors (crown gall) at the base of the stem of many cultivated or not, woody or herbaceous species (fruit, ornamental species). Although the tomato is sensitive to this bacterium, it serves as a test plant to confirm the pathogenicity of bacteria suspected of belonging to this species, attacks of A. tumefaciens on this nightshade are rare.
In France, the symptoms caused by this bacterium have only been observed on rare occasions, mainly in greenhouses located in the south-east of France. Two types of attacks were observed:
- on all the roots of plants produced above ground on peat. In this situation, galls that are initially small and pearly develop gradually over the entire root system (figure 1);
- at the level of the collar of tomato plants grown in soil on rock wool. In this case, more or less large tumors were visible at the foot of some plants (Figures 2 and 3).
Unlike many root pests, no particular structure can confirm the presence of this bacterium in root cells.
The harmfulness of this bacteriosis does not appear to be significant, whatever the nature of the attack. During heavy attacks, tumors on the roots and crown can still disrupt the development of plants, reducing their growth and inducing leaf chlorosis.
For more information on this bacterium, you can consult the sheet Agrobacterium tumefasciens .
In France, the symptoms caused by this bacterium have only been observed on rare occasions, mainly in greenhouses located in the south-east of France. Two types of attacks were observed:
- on all the roots of plants produced above ground on peat. In this situation, galls that are initially small and pearly develop gradually over the entire root system (figure 1);
- at the level of the collar of tomato plants grown in soil on rock wool. In this case, more or less large tumors were visible at the foot of some plants (Figures 2 and 3).
Unlike many root pests, no particular structure can confirm the presence of this bacterium in root cells.
The harmfulness of this bacteriosis does not appear to be significant, whatever the nature of the attack. During heavy attacks, tumors on the roots and crown can still disrupt the development of plants, reducing their growth and inducing leaf chlorosis.
For more information on this bacterium, you can consult the sheet Agrobacterium tumefasciens .
Figure 1
Figure 2
Figure 3