Biology, epidemiology

- Conservation

The biology of Xanthomonas campestris pv. vitians is poorly defined; this bacterium would behave quite similar to that of Pseudomonas cichorii . It is preserved and is transmitted by the seeds of cultivated lettuce. It is found in the epiphytic state on wild lettuce ( Lactuca serriola ) and on some weeds, especially compounds, Matricaria matricarioides It is reported in Germany on tomato and pepper. This bacterium can be maintained from year to year in an infested plot.


- Penetration

When seeds are contaminated, the bacteria can be found very quickly on the first leaves of a few seedlings in the nursery and, subsequently, on most of them if sprinkler irrigation is used. In the open field, its epiphytic installation on salads can be premature. Once on the leaf surface, Xanthomonas campestris pv. vitians mainly penetrates in the presence of free water on the limbus by natural means: via the stomata and hydatodes.


- Dissemination

Once the tissues are invaded, many bacteria exude alterations. They are dispersed to other leaves or other healthy plants by splashing during rain or sprinkler irrigation and the effects of wind and drafts in shelters. The seeds, which preserve the bacteria, certainly contribute to its dissemination to other farms and new plots.


- Conditions favorable to its development

As with the majority of bacteria, its evolution is always preceded and accompanied by wet periods. Morning dews, rains and copious sprinkling irrigations are particularly favorable to it. It develops at temperatures between 0 and 35 ° C, the thermal optimum being between 26 and 28 ° C. This bacterium would be killed from 52 ° C. The wounds, the damage resulting from frost, predispose the leaves of the head of lettuce to infections.