- classification : Fungi, Ascomycota, Leotiomycetes, Leotiomycetidae, Helotiales, Sclerotiniaceae
- téléomorphe : Botryotinia
- English name: gray mold


This fungus, ubiquitous and very polyphagous, is observed on tomatoes in practically all of its production areas around the world , where it can cause occasional significant damage. If it is rife in the open as well as in shelters, it is particularly feared in the latter context, especially for the cankers it causes on the stems. These inexorably surround the stem and are the cause of the dieback of the distal parts of many plants. In some greenhouses, up to 25% of the plants can be affected. Under these conditions, it becomes difficult to manage the irrigation of plants in breads where plants are missing. Rots on fruits are also very damaging, both in greenhouses and in the open field, during cultivation and after harvest (during storage, transport and marketing).

The France was not immune : Botrytis cinerea rampant both in the field and under cover, but in this case that the attacks are often the most severe, the environment there is generally wetter. In addition to climatic characteristics, the cultivation period in these production systems is often very long, sometimes covering almost the entire year. Under these conditions, the plants present numerous stripping and disbudding wounds, which are very favorable to the establishment of this opportunistic fungus. In addition, the latter very easily colonizes senescent or weakened tissues (constituting nutrient bases), which are very present in this type of crop. They allow it to settle on plants or to conserve and multiply in this environment.


The biological variability of B. cinerea is still poorly understood . It should be noted that strains resistant to several fungicides have been reported in many countries.

Rather recent molecular biology work has revealed great genetic variability within the species B. cinerea . This fungus is in fact a complex of species that can be divided into two groups. The group I or " subpopulation pseudo cinerea " is distinguished by its resistance to the fungicide fenhexamid and has one of the two alleles of the gene " Bc hch " vegetative incompatibility. The Group II consists of the stem vacuma and transposed . The transposa subpopulation has two active transposons in its genome, Boty and Flipper whereas these two transposons are absent or inactive in the vacuma subpopulations and pseudo-cinerea .

It should be noted that a certain specialization has been demonstrated in Canada, from 91 strains of B. cinerea from tomatoes, essentially based on their greenhouses of origin, and not on their geographical origin or their isolated hosts.