- classification : Bacteria, Proteobacteria, Gammaproteobacteria, Pseudomonadales, Pseudomonadaceae
- English name: bacterial speck


Pseudomonas syringae pv. tomato is a Gram-, rod-shaped bacterium now present in all areas of tomato production . It causes significant damage when the climatic conditions are cold and wet. It manifests itself above all on field crops, in particular on varieties intended for canning, making the fruit unsuitable for marketing and processing. It is also found in unheated shelters where water condensation is high and temperatures rather low.

In France , where it is rife in the open fields as well as under shelters, it is particularly feared by industrial tomato producers. Fortunately, the use of resistant varieties has limited its incidence.

Two races have been described: race 0 (the common strain) and race 1 bypassing the resistance conferred by the incompletely dominant gene " Pto ".