• During cultivation

When you observe symptoms due to an attack of one of these Sclerotinia spp. on stems (collar or pruning wounds), on vegetation or on fruits in flat culture, a treatment with a fungicide can be carried out. Currently, no fungicide is approved for this use on tomato in France ( e-phy ).
It should be noted that strains resistant to benzimidazoles ( benomyl, carbendazim, etc.) and to quintozene have been reported in the literature. Also, it is advisable to alternate fungicides with different modes of action.

Several prophylactic measures must complement the chemical control in order to reduce the ambient humidity and avoid the presence of free water on the plants: aerate as much as possible and possibly heat the shelters, and irrigate preferably during the morning and at the beginning of the day. afternoon - never in the evening. Remember that localized irrigation is preferable to other irrigation methods.

The plant debris will be disposed of during cultivation, especially the affected plants on which these fungi produce numerous sclerotia, but also the end of culture to avoid their conservation in the ground after burial. Nitrogen fertilization will also be controlled. It should be neither too strong (at the origin of very receptive succulent tissues), nor too weak (sources of chlorotic leaves constituting ideal nutritional bases for them).

• Next crop

If the nurseries are carried out each year in the same shelter, it is essential to put in place hygiene measures .

Note that in the absence of culture, immersion of infested plots would reduce the number of viable sclerotia present in the soil.

The efficiency of crop rotations is quite disappointing; this situation is certainly due to the polyphagia of these two Sclerotinia spp. However, heavily contaminated soils justify such rotations, of at least 5 years. It will be in our best interest to alternate tomato crops with, for example, cereals. It should be noted that the cultivation of broccoli cabbage and the burying of its residues allow the United States to reduce the number of sclerotia in the soil and the damage caused by S. minor . In this country, it is considered that corn, cereals, onions, spinach are not conducive to the development of these two Sclerotinia . Green manures sensitive to these fungi will also not enter rotations, although some organic amendments reduce the damage of S. sclerotiorum .

Repeated cultivation of plants susceptible to one or both Sclerotinia spp. on the same plots will inexorably lead to an increase in soil inoculum. In this case, several preventive control means can be considered, such as soil disinfection . Several fumigants can be used ( e-phy ): dazomet, metam-sodium ... However effective they are, some of them nonetheless pose material problems and cause a number of disadvantages:
- destruction of natural microorganisms antagonists of certain pathogenic agents;
- increased receptivity to parasites in disinfected soil;
- appearance of toxicity phenomena (excess of exchangeable manganese, excess ammonia following a more or less complete blockage of nitrification, etc.).

Note that in the United States, metam-sodium is applied by spraying or through the localized irrigation system to control S. minor .

In sunny production areas, solar disinfection of the soil ( solarization or pasteurization) can be implemented with some efficiency. It consists of covering the soil to be disinfected, which will have been carefully prepared and moistened beforehand, with a polyethylene film 35 to 50 µm thick, held in place for at least one month at a very sunny period of the year. This economical and efficient method will make it possible to control the colonizing fungi of the superficial soil zone.

The steam is also effective against these fungi.

The soil of the future tomato plots will be well worked and drained in order to avoid the formation of puddles, particularly conducive to the formation of apothecia responsible for aerial contamination of S. sclerotiorum . Deep plowing will bury the sclerotia in depth, which will then be more quickly destroyed by antagonistic soil microorganisms. In the open field, the rows of planting will be oriented in the direction of the prevailing winds so that the collar of the plants and the vegetation cover are well ventilated. The use of plastic mulch will partially isolate the vegetation from the soil and therefore help reduce contamination linked to the two Sclerotinia spp. and Rhizoctonia solani . In addition, in some cases, it will help trap the ascospores released by the apothecia of S. sclerotiorum .

Of preventive fungicide treatments may be made in the case of very high inoculum pressure. Their number will fluctuate depending on the time of year, the type of crop (open field, under cover, in soil, above ground, etc.) and on the production area. Remember that currently, no fungicide is approved for this use on tomatoes in France.

The other diseases and pests must be controlled because they are the cause of wounds, tissue necrosis conducive to the installation of these two fungi. In the open field, abundant vegetation should lead to vigilance, especially in period of cloudy and wet weather.

To our knowledge, no resistance to these fungi is reported in the genus Lycopersicon .

Finally, it should be noted that several antagonist fungi and bacteria have been evaluated in vitro or in the field to control these 2 Sclerotinia spp. : Streptomyces griseoviridis, Coniothyrium minutans, Gliocladium virens, Sporidesmium sclerotivorum, Talaromyces flavus, Trichoderma harzianum … We should add that Coniothyrium minutans is now approved for this use in France ( e-phy ).