Incriminated pests and

non-parasitic diseases

The damage observed on tobacco leaves, during curing and storage, can be caused by quite diverse diseases. 

 
♦ They may be related to the development of micro-organisms:
  - like fungi, such as Alternaria alternata, the Botryosporium spp., Botrytis cinerea (figure 1), Cladosporium spp., Fusarium spp., Rhizopus spp. (Rhizopus arrhizus, Rhizopus stolonifer ...), Sclerotinia sclerotiorum (figure 2), Verticillium dahliae  (figure 3), and various moulds (Aspergillus spp., Penicillium spp., Nigrospora sp., Geotrichum sp., Etc..) (figure 4);
 - many bacteria, such as Pectobacterium spp. and Pseudomonas cichorii  (figure 5), but they are rarely observed;
 - but also a variety of viruses (CMV, AMV, PVY ...) (figure 6) and phytoplasma causing stolbur.
 
 

Figure 1	Figure 2	Figure 3	Figure 4	Figure 5

Figure 6	Figure 7	Figure 8

 
 
Some of these micro-organisms are particularly favoured by certain leaf curing methods. Thus Botryosporium sp., Botrytis cinerea, Sclerotinia sclerotiorum are often observed during air-curing, along with various moulds. Rhizopus arrhizus is more common in flue-curing of Virginia tobacco.
 
♦ Some non-parasitic diseases may cause impairment of leaves, without intervention of any micro-organism. This is the case when tobacco plant turns grey ("grey tobacco") or has green spots.