• During cultivation

When the first spots or the first cankers observed affect a limited number of plants, it may be advisable to remove them quickly and carefully by placing them in a plastic bag before removing them from the crop.

During cultivation, treatments with fungicides * can be carried out ( e-phy ).

Sprinkler should be irrigations avoided which promote germination, development and sporulation of Didymella lycopersici .

Plant debris must be removed from the plots and destroyed. They must in no case be buried in the ground.

• Next crop

French seeds and young plants are normally free from contamination. In countries where their sanitary quality is suspect, care should be taken to use unaffected seeds .

Careful disinfection of the nursery should be carried out among producers who themselves ensure the multiplication of their young plants when the latter are chronically affected by D. lycopersici .

When possible (especially in the open field), crop rotations of several years will be considered. It will of course be advisable to avoid alternating the tomato with other Solanaceae or leaving weeds of this botanical family in the plot or its environment, in particular the black nightshade which must be destroyed fairly systematically.

Certain particularly contaminated soils may be subject to disinfection. The method used will vary depending on the country and the type of crop: steam, fumigant (dazomet, metam-sodium, etc.), solarization . The latter method, used in particular in Sicily and Morocco, seems particularly advantageous for greatly reducing the quantity of inoculum on the soil surface. Note that the rootstocks resulting from interspecific crosses are resistant to D. lycopersici . Grafting will be of interest if the attacks are mainly localized at the neck.

The greenhouse environment and the equipment that has been in contact with diseased plants must be carefully disinfected (bleach, fumigants, various products; you can consult the sheet Passalora fulva for more information). The stakes can be solarized. They will be covered with a transparent polyethylene film and exposed as they are to solar radiation in summer. The high temperatures obtained under the film will destroy a large proportion of the resident inoculum, this fungus being eliminated at more than 50 ° C.

Treatments with the fungicides recommended above can be carried out preventively, in particular after pruning in wet periods. Pruning wounds will be protected with a fungicidal spray in water or mineral oil. Iprodione and fenarimol are said to be satisfactory.

Sprinkler irrigations will be performed at times of the day allowing rapid drying of the vegetation. However, we prefer localized irrigation.

While no variety currently on the market shows resistance to this fungus, Lycopersicon hirsutum has a high level of resistance to D. lycopersici . It is certainly for this reason that the rootstocks of the KNVF type, interspecific hybrids between this species and the tomato, are resistant to this parasitic fungus. Resistance is believed to be dominant and controlled by more than one gene.

It should be noted that some attempts at biological control of D. lycopersici by Trichoderma harzianum varying have been carried out with degrees of success.

* 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.