Protection methods

• During cultivation 

To control * Botrytis cinerea A set of prophylactic measures complementary to chemical control should be implemented, both in the nursery and in the open field.

The shelters must be ventilated as much as possible, in order to reduce the ambient humidity and, in particular, to avoid the presence of open water on the plants.

For trained crops, pruning and leaf stripping should be taken care of and carried out in the morning, because at this time, the tissues, more turgid, cut more easily, and the wounds then have more time to dry during the day. . It will not be desirable to prune during cloudy and wet periods. Note that wounds on the stem, although appearing dry, remain susceptible to B. cinerea for quite a long time.

The young cankers on the stem will be cured in order to eliminate the tissues colonized by this fungus. The wounds must be protected by a fungicide applied locally in the form of a whitewash or by means of generalized preventive treatments.

Under shelters, the ' irrigation will take place only when the plants are able to evaporate. In the open field, the sprinkler irrigations carried out more in the morning and never in the evening will allow the plants to dry out as quickly as possible.

We will avoid any stress to the plants leading to spurts of growth. The nitrogen fertilizer should be controlled. It will be neither too strong (at the origin of very receptive succulent tissues), nor too weak (sources of chlorotic leaves constituting ideal nutritive bases for B. cinerea).

In dying plants with one to more cankers on the stem, rotten fruits on which B. cinerea sporulates will be quickly removed from crops. At the end of cultivation, all plant debris must be quickly removed from shelters and plots in the open field. In the latter context, this will prevent them from being subsequently buried in the soil and the fungus being able to remain there. Deep plowing will facilitate the decomposition of the few remaining waste.

During periods of risk, fungicide treatments can be carried out under shelter, in particular on trained cucumber and melon plants, following harvests and leaf stripping in order to protect pruning wounds. When a chancre forms at their level, the lesion can be healed in order to rid the stem of diseased tissue. A thick fungicidal spray will be applied, taking care to cover the wound well. Currently, a few ** active ingredients are authorized for Botrytis- melon ( e-phy ) use.

* Controlling B. cinerea has been and still is difficult, especially under shelters. This situation has several explanations:
- a climate completely favorable to the development of this fungus;
- particularly receptive plants, with more succulent and tender organs than in the open field and numerous wounds caused by pruning and disbudding in the case of cucumbers for example;
- a particular aptitude of this fungus to adapt quickly to the fungicides which can be used for a “ use Botrytis ” on numerous plants, and belonging for a very long time to a sometimes too limited number of chemical families to carry out judicious alternations;
- few fungicides with different modes of action available (not yet approved, withdrawn from the market following recent European legislation on pesticides).
** Note that several families of fungicides are affected by resistance phenomena.  It is therefore strongly recommended to alternate the chemical families in order to avoid the appearance of resistant strains.

• Next crop

Of course, the measures recommended during cultivation will be systematically applied during the next cultivation. They may be supplemented by other interventions.

The polyphagia of B. cinerea , its saprophytic abilities and the fact that the inoculum can come from the culture environment make the efficiency of rotations crop disappointing. In the open field, the soil of the future plots will be well prepared and drained in order to avoid the formation of puddles of water conducive to a microclimate of the vegetation cover favorable to attacks by B. cinerea .

The rows of plantation should be oriented if possible in the direction of the prevailing winds so that the vegetation cover is well ventilated. It will be desirable to plant the melon plants on hillocks and to use a plastic mulch with a thickness greater than or equal to 25 microns and not micro-perforated. Avoid setting up the crop with too high densities and injuring the plants. Under shelters, it will be desirable to create a crawl space, to replace any plastic covering the ground, and to disinfect the greenhouse carefully.

Regarding fertilization , it must be balanced, in no case excessive in nitrogen. In the open field, as under shelter, we advise you to opt for a localized irrigation system drip , avoiding wetting the vegetation as is the case with sprinkler irrigation is employed.

treatments fungicide Preventive will rarely be essential, except under shelter during periods of risk ( e-phy ).

Of plant extracts , some microorganisms , were more or less effective with regard to B. cinerea , none of them is currently used in production, probably because of a very partial efficacy in epidemic conditions.

The other diseases and pests must be controlled because they are the cause of wounds, tissue necrosis conducive to the establishment of B. cinerea . As soon as the vegetation becomes important, it will be necessary to be vigilant, especially in cloudy weather.


* 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.