Protection methods

• During cultivation 

When you observe symptoms due to an attack of Sclerotinia sclerotiorum on the vegetation and the climatic conditions are wet and cold, it would be advisable to carry out a treatment with a fungicide *, but unfortunately no fungicide is registered for this use on melon in France ( e-phy ).

* It should be noted that strains resistant to benzimidazoles ( benomyl, carbendazim, etc.) and to quintozene are reported in the literature. Also, it is advisable to alternate fungicides with different modes of action.

It is therefore necessary to put in place some prophylactic measures that will 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 in the early 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 plants and fruits affected on which the fungus forms 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

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 polyphagia of S. sclerotiorum. However, heavily contaminated soils justify such rotations, of at least 5 years. It will be in your best interest to alternate melon crops with, for example, cereals. Green manures sensitive to these fungi will also not enter rotations, although some organic amendments reduce the damage of S. sclerotiorum .

A soil disinfection may be considered if it is heavily infested. Several fumigants can be used ( e-phy ): dazomet and metam-sodium ... As effective as 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.).

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 this fungus.

The soil of the future melon plots will be well worked and drained in order to avoid the formation of puddles favorable in particular to the formation of apothecia responsible for aerial contaminations 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 and in particular the fruits from the soil, and therefore will help reduce contamination linked to this Sclerotinia , but also to 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. The products mentioned above can be used. Remember that currently no fungicide is approved on melon in France to carry out preventive treatments on vegetation ( e-phy ).

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

To our knowledge, no resistance to this fungus has been reported in melon.

Let us add that Coniothyrium minutans is now approved for this use in France ( e-phy ).


* Chemical control : As the number of pesticides available for a given use is constantly changing, we advise you to always confirm your choice by consulting the e-phy site of the Ministry of Agriculture and Fisheries which is an online catalog of plant protection products and their uses, fertilizers and growing media approved in France. This also applies to all biological products based on microorganisms or natural substances.