- Classification: Fungi, Ascomycota, Leotiomycetes, Leotiomycetidae, Helotiales, Sclerotiniaceae
- Teleomorph: Botryotinia
- English name: Gray Mold


This ubiquitous and highly polyphagous fungus is observed on tomatoes in practically all of its production areas around the world, where it can occasionally cause significant damage. If it is prevalent in both open fields and shelters, it is particularly concerning in the latter context, especially for the cankers it induces 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 beds 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).

France is not immune to this issue: Botrytis cinerea is rampant both in the field and under cover, but in this case, the attacks are often the most severe, and 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 highly favorable for the establishment of this opportunistic fungus. Additionally, it easily colonizes senescent or weakened tissues (constituting nutrient bases), which are prevalent in this type of crop. They allow it to settle on plants or to persist 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 significant genetic variability within the species B. cinerea. In fact, this fungus is a complex of species that can be divided into two groups. Group I, or the "subpopulation pseudo cinerea", is distinguished by its resistance to the fungicide fenhexamid and has one of the two alleles of the gene "Bc hch" involved in vegetative incompatibility. 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's important to note that a certain specialization has been demonstrated in Canada, among 91 strains of B. cinerea from tomatoes, primarily based on their greenhouses of origin rather than their geographical origin or isolated hosts.