Protection methods

Fusarium wilt is a formidable disease that is difficult to control in the field. Only the implementation of a maximum of measures and methods recommended thereafter will make it possible to limit its effects.

• During cultivation

No control method, no product can effectively control this disease during cultivation.

It is essential to eliminate diseased plants as soon as the first symptoms appear.

The tools used for various interventions in the contaminated plots will be well cleaned before their use in healthy plots, without forgetting the wheels of the tractors. Thorough water rinsing of this material will often be sufficient to rid it of infested soil.

Many growers have the unfortunate habit of burying crop residues in the soil after harvest. The buried plant tissues are abundantly colonized by Fusarium oxysporum f. sp. melonis which produces many chlamydospores there. Eliminating plants with their root system limits this phenomenon and helps reduce the amount of inoculum in the plots.

• Next crop

It will be necessary to use quality seed , free from contamination; it will be the same for the substrate and the plants; producers will have an interest in checking the sanitary condition of the latter at the time of delivery. The plants produced should not come into contact with the soil, especially if the latter has not been disinfected. The installation of a plastic film will insulate them.
In infested farms, nurseries will be disinfected (soil and shelter structures) as well as the material and substrate used. The substrate should not be stored in bulk outside the greenhouses and it should especially not be mixed with earth or sand collected in nature.

The crop rotations are generally ineffective since chlamydospores survival potential of this fungus in the soil, but also its ability to maintain the organic matter of many plant species. To hope for efficiency, it would be advisable to ban melon production for at least 8 years in cultivated plots. We should add that cases of Fusarium wilt in summer have been reported on soils that have never grown melon, which says a lot about the difficulties encountered in managing rotations.

The different methods of disinfection of the soil past (fumigation - methyl bromide, chloropycrin -, application of fungicides at the foot of plants) and current (biofumigation, solarization, etc.) have made it possible or make it possible to more or less reduce the incidence of fusarium but at unsatisfactory levels for the moment. Indeed, the recolonization of superficially disinfected soils occurs very quickly, calling into question their value, F. oxysporum f. sp. melonis can live up to 1 m, even 1.5 m deep.
Chemical disinfection of soil has been used with varying degrees of success, but its use is no longer relevant. The solarization would limit Fusarium, particularly when it is coupled to a biofumigation, or bringing biological products based on Trichoderma harzianum or griseoviridis Streptomyces .

Note that soils resistant to this fusarium wilt were discovered in the region Chateaurenard many years ago. The nature of the resistance of these soils has been studied but this knowledge has not led to a practical application of this phenomenon. Despite this, the durability of this resistance in the soils concerned should not be called into question by disinfecting the soil with a fumigant.

should be avoided fertilization Excessive nitrogen , on the other hand liming would reduce the effects of this disease.

In cultivation under cover, it is also desirable to disinfect structures, equipment and nutrient solution supply circuits. For this, you can use a 3% formalin or bleach ( e-phy ) solution.

For many years, by far the most effective method of controlling this vascular fusarium wilt has been the use of resistant varieties . The use of the latter is still current, but unfortunately during the last decade, the generalization of race 1-2 in many soils, the presence of more aggressive strains, and the too partial resistance of hybrids to this race have somewhat discredited this method.

The grafting is an ancient technique that is increasingly used to control Fusarium wilt under shelter, and now in the field. Currently, two types of rootstocks can be used:
- a hybrid squash between Cucurbita moscata and Cucurbita maxima . Its level of resistance to fusarium is excellent, moreover it is not susceptible to Verticillium dahliae and Phomopsis sclerotioides . On the other hand, it is attacked by root-knot nematodes belonging to the genus Meloidogyne . This hybrid is also much more rustic, it tolerates cold spring soil conditions better and it is not very sensitive to limestone;
- a variety of melon resistant to Fusarium wilt having in particular partial resistance to race 1-2. On the other hand, this material is sensitive to other soil-borne pests reported previously, moreover resistance to fusarium wilt is only intermediate.
Note that the adoption of grafting requires the first years to develop a production system optimizing this new plant material. In addition, it will be advisable not to make the grafting point too low, and not to bury the plants too deeply when planting, in order to avoid the phenomenon of franking (emission of roots from the graft) putting back in cause the interest of this alternative method.

Divers Save waste ( Aconitum leucostomum , Apium graveolen s Euphorbia fischeriana , Euphorbia helioscopi in , Inula viscose , Micromeria nervous , Origanum syriacum , Peganum harmal at Plumbago Maritim in ...), and microorganismes antagonistes ( Bacillus subtili s Paenibacillus ithout the , Pseudomonas fluorescens , P. putida , Sphingobacterium multivorum , Streptomyces olivaceu s - Aspergillus niger , Glomus intraradice s, Penicillium oxalicum , Trichoderma harzianum tested worldwide , T. viride …) have been for F. oxysporum f. sp. melons less success with more or .

* 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.