Biology, epidemiology  

• Conservation, sources d'inoculum
  

Pectobacterium carotovorum subsp. carotovorum is ubiquitous and is present in many soils in which it easily persists for several years, especially in plant debris and in the aqueous phase. It is also found in the phylloflora of zucchini and squash. Polyphagous , this bacterium is likely to persist on a fairly large number of hosts, whether or not cultivated, especially herbaceous dicotyledons. It is rife on many vegetables, including various Cucurbitaceae, but also Solanaceae such as potatoes, tomatoes, eggplants and peppers. It is also found on salad, celeriac, cabbage, basil, fennel ...

• Penetration and invasion

It penetrates the various organs of the zucchini, mainly through wounds (stripping or harvesting wounds, mechanical wounds, etc.), but also via the stylar end of the fruits. It is a parasite of weakness which can also occur secondarily after other pathogens, in particular Didymella bryoniae on squash. Once in place, its cellulolytic and pectinolytic enzymes actively contribute to its rapid extension into tissues which soon rot and sometimes take on a foul odor.

• Multiplication and dissemination

Like many bacteria, it multiplies easily in infected tissue where bacterial cells swarm, and is easily disseminated by water , splashing and dripping. The insects , as well as tools during cultivation practices, contribute to its dispersion.

• Conditions favorable to its development

They are mostly humid and hot . Cloudy and rainy periods increase the risk of this bacteria proliferating. It appears able to grow at temperatures between 5 and 37 ° C, the optimum being between 25 and 30 ° C . In dry soils, where the humidity is less than 40%, the development of P. carotovorum subsp. carotovorum seems to regress, and in some situations it goes away.

Very vigorous plants seem more sensitive.