Protection methods

The control of Monosporascus cannonballus is not easy because this fungus is preserved for a long time in soils and substrates, and multiplies there very quickly. Also, it will be advisable to combine all the measures and methods allowing to limit its development or to eliminate it.

• During cultivation 

It is extremely difficult, if not impossible, to control an attack of M. cannonballus during culture, in particular for the following reasons:
- leaf symptoms of the disease are frequently late; at this stage, the poor condition of the roots does not allow the implementation of effective measures and the restoration of the health of the roots;
- melon is a plant which does not easily regenerate a complementary root system;
- finally, it is not easy to reach in the soil the pests present on and in the roots
It is therefore unfortunately too late to intervene.

In order to try to keep the plants alive as long as possible, you should:
- to bathe the plants during the hottest periods of the day in order to avoid excessive and uncompensated evaporation, leading to wilting, drying out and death of the plants;
- carefully monitor the irrigation . Indeed, if the plants wither, it is not necessarily linked to a lack of water, but rather to root alterations due to M. cannoballus . In some cases, growers tend to increase irrigation to respond to wilting, leading to amplification of root lesions through asphyxiation.

In order to avoid transmitting the disease to other plots, footbaths will be installed in front of each entrance to the shelters, the disinfectant solution having to be renewed frequently. The movement of workers will be controlled, and tillage machinery used in the affected plot will be thoroughly washed before re-use elsewhere. It will also be recommended to avoid visitors.

We advise you above all to eliminate and carefully destroy diseased plants and in particular their root systems, in progress, but basically at the end of cultivation. In fact, by destroying the infected roots, the perithecia formed on the latter as well as the numerous ascospores, important sources of inoculum subsequently, will be eliminated at the same time.

Let us add that the plant debris will not be piled up and kept near the plots, or shelters, where Cucurbitaceae will be cultivated subsequently and in particular melon or watermelon. It will be better to destroy them by using quicklime or by burning them.

• Next crop

In the event that the nurseries are carried out each year in the same shelter, it will be essential to use healthy substrates (disinfected), to avoid placing the clods on the ground because they often become contaminated in contact with the latter, especially if it has not been disinfected and / or if it is not covered by a plastic film.
It will be essential to use healthy plants . They should be produced with a healthy substrate. Trays and crates reused to contain the plants will be disinfected. We will be particularly vigilant about their sanitary quality. Those from farms affected by this fungus will not be accepted.

The crop rotations are interesting when they are sufficiently long and made preventively, before the soil is contaminated. In the latter case, their effectiveness is relative because the fungus keeps for a long time in the soil. In addition, it should be noted that it can multiply on various alternative hosts that are still poorly understood. Let us add that this fungus is indigenous in the soils of certain regions where Cucurbitaceae have never been cultivated.

The soil must be well worked to allow optimal rooting.

Heavily contaminated soils can be disinfected. Several fumigants can be used (dazomet, metam-sodium, dimethyl disulfide ). If these fumigants are more or less effective, some of them pose material problems and lead to 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 complete or partial blockage of the nitrification ).

It should be noted that in some countries, localized fungicide treatments of the soil (thiophanate-methyl, fluazinam, fludioxinil ), via the drip irrigation system, have been tested. The efficacy of these fungicides, as well as that of a few other products, has not always been efficient and some of them have been shown to be phytotoxic.

The solar disinfection of the soil (solarization or pasteurization) does not seem possible to effectively reduce the damage caused by Mr cannonballus . Indeed, this thermophilic fungus tolerates quite well the temperatures induced in the soil by this method. On the other hand, coupled with reduced dose fumigation, the efficiency of solarization seems satisfactory.

In cultivation under cover, in particular above ground, the entire farm must be disinfected in order to get rid of as many more or less adherent propagules as possible, liable to contaminate the new plants. Bags, substrate cubes, tools and other materials that may have been contaminated will be disposed of. If they are reused, they will need to be disinfected first.

Tools used for tillage in contaminated plots should be thoroughly cleaned before use in other healthy plots. It will be the same for the wheels of the tractors. Thorough water rinsing of this material will often be sufficient to rid it of infested soil. Let us add that the other measures recommended previously when the disease manifests itself during cultivation will also be implemented.

No source of resistance high level could be identified in melon and watermelon. However, a few melon lines have been shown to be tolerant to M. cannonballus .

While waiting for resistant cultivars, grafting melon and watermelon on a resistant rootstock remains an interesting alternative. Several species of Cucurbita and Lagenaria are used as rootstocks. Let us add that some resistant cucumber cultivars (Baekbon and Eunhwa) have been highlighted; they could also be used for grafting purposes. It should be noted that these rootstocks still allow M. cannonballus to develop and that their monoculture on the same plots could ultimately lead to situations just as damaging as those observed on sensitive melon and watermelon crops.

* Chemical control : 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 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.