Crops
Protection methods
- During cultivation
If you are faced with attacks of Thanatephorus cucumeris ( Rhizoctonia solani ) in the nursery, we advise you to eliminate diseased plants and those nearby. If you have any doubts, you can carry out foliar treatments * with the following fungicides: pencycuron, boscalid + pyraclostrobin as well on lettuce as on escarole and frisée (note that only preventive treatments are really effective on crown rots in salads ). Subsequently, especially after planting, one to three applications may be made, the last treatment being at the maximum at the 11-13 leaf stage.
In greenhouses, it is advisable to control the climate as much as possible in order to avoid excess humidity and temperature. For this, the shelters will be well ventilated. Good wiping of the soil after rains and sprinkler irrigation should be encouraged. Maintain balanced fertilization and carefully remove plant debris and diseased plants at the end of cultivation.
- Next crop
To avoid introducing this parasitic fungus into your farm, it will be essential to use a healthy substrate and quality plants. Plants produced in mini-clods should not be placed directly on the ground, especially if it has not been disinfected; a plastic film will have to insulate them. If you produce your plants, we advise you to apply the recommended hygiene and disinfection measures .
Of fungal treatments to seeds can also be realized. They can be based on iprodione on witloof chicory or on propamocarb HCl associated with fosetyl-aluminum on lettuce .
In contaminated soils, one of the following options may be chosen, depending on the technical and commercial requirements of the producer:
- in the case of a field crop, we can combine a treatment of the soil * before planting with a fungicide (pencycuron, iprodione) (both on lettuce and chicory as on escarole and curly ) with a mulching of the latter with plastic film. After planting, foliar treatments with some of these fungicides can be carried out in order to complete the effectiveness of these measures, this according to the same methods as those specified previously;
- under shelter, an approach comparable to that described above could be considered, except perhaps plastic mulching of the ground.
A soil disinfection * with a fumigant may be considered. Those which are conventionally used (metam sodium alone or in combination with dimethylpolysiloxane, dazomet) ( e-phy ) are effective with regard to Thanatephorus cucumeris . The same is true for steam . Particular care should be taken to avoid re-infecting disinfected soil after treatment.
In production areas where it can be applied, solar disinfection of the soil (solarization) will be carried out; rather spectacular results have been recorded in particular in certain Mediterranean countries. It consists in covering the ground, which will have been very well prepared and moistened beforehand, with a polyethylene film 35 to 50 µm thick. This will be kept in place for at least a month at a very sunny time of the year. It is an economical, efficient method which makes it possible to get rid of this colonizing fungus from the surface area of the soil.
Of course, the agrocultural measures recommended during cultivation must be implemented. In addition, heavy and humid soils will be drained and plowing will be carried out before planting in order to destroy some of the sclerotia which are more quickly destroyed in depth. Crop rotations can be carried out with cereals, sweet corn, fodder grasses and onions. We will plant the salads on hillocks. This will prevent the salad leaves from coming into contact with water and will promote better aeration of the plant necks. Fertilization should be balanced, in no case too low in nitrogen.
There is thing no such as a resistant variety . Certain types of salads with a more upright habit, such as romaine, for example, appear to be less affected.
For information, microorganisms antagonistic have been tested to control Thanatephorus cucumeris ( Trichoderma harzianum , Trichoderma koningii , Burkholderia cepacia, etc.). Although sometimes promising, the use of these microorganisms is not yet sufficiently reliable to be able to recommend them in the field.
If you are faced with attacks of Thanatephorus cucumeris ( Rhizoctonia solani ) in the nursery, we advise you to eliminate diseased plants and those nearby. If you have any doubts, you can carry out foliar treatments * with the following fungicides: pencycuron, boscalid + pyraclostrobin as well on lettuce as on escarole and frisée (note that only preventive treatments are really effective on crown rots in salads ). Subsequently, especially after planting, one to three applications may be made, the last treatment being at the maximum at the 11-13 leaf stage.
In greenhouses, it is advisable to control the climate as much as possible in order to avoid excess humidity and temperature. For this, the shelters will be well ventilated. Good wiping of the soil after rains and sprinkler irrigation should be encouraged. Maintain balanced fertilization and carefully remove plant debris and diseased plants at the end of cultivation.
- Next crop
To avoid introducing this parasitic fungus into your farm, it will be essential to use a healthy substrate and quality plants. Plants produced in mini-clods should not be placed directly on the ground, especially if it has not been disinfected; a plastic film will have to insulate them. If you produce your plants, we advise you to apply the recommended hygiene and disinfection measures .
Of fungal treatments to seeds can also be realized. They can be based on iprodione on witloof chicory or on propamocarb HCl associated with fosetyl-aluminum on lettuce .
In contaminated soils, one of the following options may be chosen, depending on the technical and commercial requirements of the producer:
- in the case of a field crop, we can combine a treatment of the soil * before planting with a fungicide (pencycuron, iprodione) (both on lettuce and chicory as on escarole and curly ) with a mulching of the latter with plastic film. After planting, foliar treatments with some of these fungicides can be carried out in order to complete the effectiveness of these measures, this according to the same methods as those specified previously;
- under shelter, an approach comparable to that described above could be considered, except perhaps plastic mulching of the ground.
A soil disinfection * with a fumigant may be considered. Those which are conventionally used (metam sodium alone or in combination with dimethylpolysiloxane, dazomet) ( e-phy ) are effective with regard to Thanatephorus cucumeris . The same is true for steam . Particular care should be taken to avoid re-infecting disinfected soil after treatment.
In production areas where it can be applied, solar disinfection of the soil (solarization) will be carried out; rather spectacular results have been recorded in particular in certain Mediterranean countries. It consists in covering the ground, which will have been very well prepared and moistened beforehand, with a polyethylene film 35 to 50 µm thick. This will be kept in place for at least a month at a very sunny time of the year. It is an economical, efficient method which makes it possible to get rid of this colonizing fungus from the surface area of the soil.
Of course, the agrocultural measures recommended during cultivation must be implemented. In addition, heavy and humid soils will be drained and plowing will be carried out before planting in order to destroy some of the sclerotia which are more quickly destroyed in depth. Crop rotations can be carried out with cereals, sweet corn, fodder grasses and onions. We will plant the salads on hillocks. This will prevent the salad leaves from coming into contact with water and will promote better aeration of the plant necks. Fertilization should be balanced, in no case too low in nitrogen.
There is thing no such as a resistant variety . Certain types of salads with a more upright habit, such as romaine, for example, appear to be less affected.
For information, microorganisms antagonistic have been tested to control Thanatephorus cucumeris ( Trichoderma harzianum , Trichoderma koningii , Burkholderia cepacia, etc.). Although sometimes promising, the use of these microorganisms is not yet sufficiently reliable to be able to recommend them in the field.