Biology, epidemiology

• Conservation, sources d'inoculum
  

 If we refer to the other pathovars of Pseudomonas syringae , we can reasonably assume that this bacterium can be preserved in the soil on plant debris. It is also very likely that it develops as an epiphytic on a few weeds and / or cultivated plants. Its presence on seeds, although strongly suspected, has never been demonstrated to date.

This bacterium can also be present in the water of retention basins. It stays there during the winter and the water used the following year, either to irrigate the plants by sprinkling or to prepare the pesticide suspensions, is polluted and must contribute to contamination.

It should be added that artificial inoculations of strains P. aptata have made it possible to observe that they exhibit different aggressiveness and host ranges. The most aggressive strains were also those with the widest host range. Among the susceptible hosts, let us point out for example sugar beet, onion ...

Heavy rains or sprinkler irrigation generate splashes of soil particles suspended in the water which pollute plants.

• Penetration and invasion

 Once on the surface of the leaves, stems and wet fruits, bacterial cells must penetrate them through stomata, hydathodes, but also wounds of the most diverse nature.

• Sporulation and dissemination

  P. aptata rapidly invades tissues which soon harbor large amounts of bacteria.

Their dissemination takes place easily under the influence of water. Indeed, during rains, sprinkler irrigation, accompanied by more or less windy weather, many droplets ensure their transport to other healthy leaves.
During cultivation operations, especially if the plants are wet, bacteria can be transmitted by workers and the tools employed.

The role played by seeds and plants in the spread of this bacteriosis is not known.

• Conditions favorable to its development 

As for many bacteria, the ambient humidity and the presence of free water on the plants condition the development of this Pseudomonas . He also seems to enjoy the relatively cool temperatures.