Biology, epidemiology

- Conservation, sources d'inoculum

Pectobacterium carotovorum subsp. carotovorum is a ubiquitous bacterium (figure 1); it is present in many soils in which it persists without difficulty for several years, in particular in plant debris and in the aqueous phase. It is also found in the phylloflora of salads, which tends to prove that it is relatively frequent in the environment of this plant. It is polyphagous and therefore likely to persist on a fairly large number of hosts, whether or not cultivated, especially herbaceous dicotyledons.


- Penetration

It penetrates salads mainly through wounds (mechanical injuries, damage related to frost and marginal necrosis, acid fog, etc.) or senescent tissues, more rarely through natural openings. It is a parasite of weakness that can arise secondarily behind other pathogens. Once in place, its cellulolytic and pectinolytic enzymes actively contribute to its rapid extension in the tissues which soon rot and sometimes take on a foul odor.


- Dissemination

Like many bacteria, it is easily disseminated by water, splashing and dripping. Insects as well as workers with their tools contribute to its dispersion.


- Conditions favorable to its development

It is mainly favored by humid and hot climatic conditions. Cloudy and rainy periods increase the risk of this proliferating Pectobacterium . It contaminates much more easily salads having reached or exceeded their maturity and / or which present numerous wounds and some senescent leaves. It seems capable of growing at temperatures between 5 and 37 ° C, its optimum being between 25 and 30 ° C. In dry soils, the humidity of which is less than 40%, the development of Pectobacterium carotovorum subsp. carotovorum seems to regress, in some situations it disappears.

Poor control of the storage temperature, the presence of numerous wounds and the use of contaminated water when washing or cooling salads, promote the damage of this bacteriosis during storage and transpo