Biology, epidemiology

• Conservation, sources d'inoculum
  

Xanthomonas axonopodis pv. vesicatoria , Gram stick, is stored for a short time directly in the soil. It holds up better on plant debris , (present on and in the ) and soil seeds several ( months or even a year some authors speak of about ten years , outdoors as inside). This pathogen would persist on wheat roots. It can also live in the epiphytic state or infect several cultivated, weeds or wild nightshades that will ensure its sustainability. Among the species mentioned are peppers ( Capsicum annuum, C. frutescens ), eggplant, Amaranthus retroflexus, Datura stramonium, Chenopodium album, Portulaca oleracea, Galinsoga parviflora, Hibiscus trionum, Hyoscyamus niger, Hyoscyamus chinese, , Lycium halimifolium, Physalis minima, Solanum dulcamara, S. nigrum, Nicandra physaloides, Lycopersicon pimpinellifolium, Nicotiana rustica somewhat controversial because, as a result of Some of these hosts are artificial inoculations, hypersensitivity reactions have could be confused with real infections. In addition, it is not really known which species belong to the 4 inoculated groups.

The primary inoculum often comes from the environment of plants or seeds.

• Penetration and invasion

After an epiphytic phase, the bacteria enter the leaflets through natural openings such as stomata and hydatodes, or through various injuries: broken hairs (trichomes), growth cracks, lesions resulting from the effects of sand or wind or insect bites ( Nezara viridula ). Subsequently, the bacteria invade the tissues and multiply there in large quantities. In 24 hours, several million bacterial cells are produced, which is a definite advantage for their dissemination, and the first symptoms appear in 5 to 6 days if the conditions are very favorable.

• Multiplication and dissemination

It is carried out thanks to the projections of water occurring during the rains and irrigation by sprinkling . The aerosol portion of these splashes (microdroplets) can be carried over longer distances by the wind , which is why in some plots the disease progresses in the direction of the prevailing winds. Thus, bacterial cells are projected to other surrounding organs and plants. Workers working and circulating in crops with wet foliage contribute to its dispersal. The seeds and contaminated plants also ensure its dissemination . Note that this bacterium was isolated from several insects: Aulacophora concta, Eucoptaera praemorsa, Phanoroptera gracilis, Henosepilachna vigintioctopunctata

• Conditions favorable to its development

This bacteria is found in hot and humid production areas . It is also rather summery and favored by fairly high temperatures. Its optimum temperature is around 26 ° C, with a developing range between 20 and 35 ° C . She appreciates hot nights, between 23 and 27 ° C. Cold nights, at temperatures below 16 ° C inhibit its development. Like all bacteria, it likes high humidity following rains, thunderstorms and dews, and irrigation by sprinkling.