Pectobacterium carotovorum subsp. carotovorum (formerly Erwinia carotovora subsp. carotovora) causes large wet dark lesions on tobacco leaves (figures 1 and 2). A yellow halo, due to the toxin emitted by the bacteria can be observed around the spots (figure 2). Note that the floral parts (figure 3) may also be infected. 
  
On the stem, the lesions are dark brown to black reaching the pith (figure 5). Infection starts from the stem and other symptoms may also be observed (for further information, see External or internal lesions of the stem). 

Rot caused by Pectobacterium carotovorum subsp. carotovorum is easily recognisable by a foul odor of the lesions. The dark brown or black spots are a characteristic symptoms of the bacterium. This bacterium is rare in France. Like in many bacterial diseases, no diagnostic sign may be observed on the tissues, which makes disease identification difficult. To confirm diagnosis with certainty, send samples to a specialised laboratory that can grow out the bacterial isolates in an artificial media and / or run more specific tests. 
 
For further information about these bacteria, please see the fact sheet on Pectobacterium spp ..