• During cultivation

Root attacks

If you observe symptoms on the root system during cultivation, it is unfortunately too late to intervene effectively on the crop. Indeed, there is no effective way to eliminate the parasite present on the roots of plants without permanently altering the latter.

As with P. lycopersici, an attempt can be made to keep the plants alive as long as possible. For this, it is necessary:
- to butter them in order to promote the emission of adventitious roots which can replace the old damaged roots. In soil-less cultivation (on peat or on pozzolan + peat) and during serious attacks, peat can be added locally to the collar to allow additional rooting. Sawdust is sometimes used;
- to bathe them during the hottest periods of the day to avoid excessive and uncompensated evaporation, leading to wilting, drying out and death of the plants;
- monitor carefully the irrigation . Indeed, if the plants wither, it is not necessarily linked to a lack of water, but rather to root alterations due to Colletotrichum coccodes . In some cases, growers tend to increase irrigation to respond to wilting, leading to amplification of root lesions through asphyxiation.

In addition, we advise you to remove and carefully destroy the diseased plants and their root system , but also the many rotten fruits, in progress but especially at the end of cultivation in order to avoid them being subsequently buried in the ground and that they enrich the inoculum of C. coccodes already present.


Attacks on fruits

The fruits , rather sensitive to anthracnose, should be harvested as soon as possible after maturity. Irrigation by sprinkling should be managed as well as possible; excess should be avoided and the rapid drying of the vegetation will be favored.

Treatments with an fungicide * authorized ( e-phy ) should be carried out, starting from fruit formation until harvest. Applications will be repeated after heavy rains and sprinkler irrigation.

• Next crop

Root attacks

In the event that the nurseries will be carried out each year in the same shelter, it will be essential to put in place hygiene measures. To produce your plants, we advise you to use healthy substrates (disinfected) and to avoid placing the clods on the ground. Indeed, they often become contaminated in contact with the latter, in particular if it has not been disinfected.

The crop rotations will be interesting if they are not carried out preventively, before the soil is heavily contaminated. They should last at least 3 to 4 years. Of course, other plants entering the rotation will not be susceptible. In addition, weeds likely to harbor the fungus will be eliminated from the plots. The soil chosen must be draining, well worked: a good subsoil will allow the roots to access new layers.

Heavily contaminated soils should be disinfected . Several fumigants can be used (dazomet, metam-sodium, etc.). You should know that these fumigants are more or less effective, some of them pose material problems and cause a number of disadvantages, in particular:
- the destruction of natural microorganisms antagonists of certain pathogenic agents;
- increased receptivity to pests and diseases in disinfected soil, potting soil and substrates.

A soil disinfection by the steam is also possible. In addition, in sunny regions, solar disinfection of the soil ( solarization or pasteurization) can be implemented. It consists of covering the floor to be disinfected, which will have been very well prepared and moistened beforehand, with a polyethylene film 35 to 50 µm thick. This is kept in place for at least a month at a very sunny time of the year. This is an economical, efficient method that will control C. coccodes .

It should be noted that soil treatments before planting have been proposed in some countries with one of the fungicidal solutions .

In soil-less cultivation, bags, pots, gutters, etc. will need to be disinfected or replaced. We have very little information on the disinfection of substrates. Steam treatment is effective if a distribution system suitable for existing installations is adopted. Metam-sodium cannot be used for substrates based on organic materials, but it should be used for all mineral substrates (sand, perlite, pozzolan). It will be necessary to work on a dry substrate, by impregnating it several times and then washing it abundantly. Formalin has been successfully tried to disinfect a mixture of pozzolan and peat (by imbibing the substrate with a 3% solution of commercial formalin).

If the soil is not disinfected, attacks can be delayed soil C. coccodes by placing the plants in warmed and / or by increasing the volume of the clods which will be prepared with a healthy substrate. It will be preferable to mulch the ground and to stake the plants in order to reduce attacks on fruits.

If the irrigation water is contaminated, an alternative source of water supply should be used.

To our knowledge, no resistance to root attacks by C. coccodes has been described. Grafting is not a possible alternative, because KNVF type rootstocks are sensitive to C. coccodes , and their intensive use leads to an inexorable increase in damage to the roots.

A genetic resistance to anthracnose on fruits was identified; it would be polygenic and partially dominant. However, the level of protection obtained is not sufficient to bypass chemical protection, especially in plots where this disease occurs frequently and with seriousness.

The use of forecasting models, developed for early blight, does not seem to make it possible to better position fungicide applications and therefore to reduce their number.

Note that some antagonistic fungi and bacteria have been evaluated in vitro or in the field to control C. coccodes: Coniothyrium minutans, Trichoderma harzianum, Streptomyces griseoviridis …

* 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.