• During cultivation

As soon as you have observed the first spots, it is advisable to ventilate the shelters as much as possible to reduce the humidity of the ambient air to below 85% and to avoid the presence of free water on the leaflets. Shelters should also be heated at certain times in order to maintain warmer night temperatures than those outside. Stripping the leaves from the base of the plants eliminates the first attacked leaves and promotes aeration of the lower parts of the plants.

Treatments can be carried out with one or more fungicides * authorized ( e-phy ). In high-risk areas, they must be carried out every week and with care. Make sure to cover the plants well with the fungicide spray, especially the underside of lower leaves. Strains resistant to certain fungicides have been detected in several countries. For example, cross resistance to flusilazole, myclobutanil and triadimefon has been demonstrated in Passalora fulva in China.

The plant debris will be disposed of fairly quickly, both during cultivation as a result of various cultural operations and end of culture after the uprooting of plants. They will have to be destroyed.

• Next crop

Before setting up the next crop, disinfection of the structures and walls of the shelters should be considered in order to destroy the spores P. fulva present. For this you can use various chemicals . In some countries, it is conventionally used a formalin water titrating from 2 to 5% and sprayed very powerfully on the walls. Formalin is also used in fumigation at a rate of 0.9 l of commercial solution (38% formaldehyde) per 100 m ³ . Potassium permanganate (360 g for the same amount of formalin per unit volume) is often added as an oxidative agent. Temperatures during disinfection must be above 10 ° C and relative humidity between 50 and 80%. The shelters will be left closed for at least 24 hours and will then be well ventilated for a day before planting. Formalin is sometimes applied by spraying at a rate of 3,500 l / ha. A solution of bleach containing 4 to 7% of commercial solution at 48 ° Chl. can also be sprayed.

Other products are commonly recommended for disinfecting the structures and walls of shelters ( e-phy ).

The heat is sometimes used between two cultures to destroy the inoculum residing in shelters. For this, they are kept closed, without ventilation, to ensure a temperature of around 57 ° C for at least 6 hours .

The sometimes polluted seeds can be soaked in water at 50 ° C for 25 minutes. be nitrogen fertilization avoided Excessive and overly vegetative plants with waterlogged tissues should .

should Too high planting densities not be used in order to promote crop aeration and the presence of dense and shady plant cover. In addition, all the sanitary and agro-cultural measures described above will be put in place preventively.

Some preventative treatments may be carried out with the fungicides recommended before, during risk periods - especially in high humidities ( e-phy ). They will take place in the morning so that the plants dry out during the day. In addition, avoid using sprinkler irrigation. Note that a decision support system, Greenman, developed to reduce the use of pesticides under cover, is being validated on tomatoes for Botrytis cinerea and P. fulva .

There are many varieties resistant to leaf blight. They are the result of intense selection work. Resistance was sought in several wild species: Lycopersicon cheesmanii , L. chilense , L. hirsutu m, L. pennellii , L. peruvianum and L. pimpinellifolium . Among the genes used, let us quote " Cf-2 ", " Cf-4 ", " Cf-5 ", " Cf-6 ", " Cf-8 ", " Cf-9 ", " Cf-11 " ... Unfortunately, more than a dozen races of P. fulva capable of bypassing one or more resistance genes present in cultivated varieties have been characterized. In Europe, many hybrids cultivated in shelters accumulate resistance genes making it possible to control most races of P. fulva . They are listed as C5 in catalogs. Note that this genetic combination is sometimes overcome in practice by a breed relatively uncommon in cultures. This is particularly the case in the Mediterranean region.

It should be noted that various biopesticides have been tested to control P. fulva : Trichoderma harzianum, Hansfordia pulvinata, Bacillus subtilis .


* 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.