Protection methods

- During cultivation

Unfortunately, there is no way to "reestablish" plants that have suffered attacks from Thielaviopsis basicola ( Chalara elegans ) in the nursery. Given the risks of spreading the disease that they pose, we suggest that you eliminate them quickly. This is particularly important if you are a plant producer.

The situation is practically comparable in culture. It is imperative that the root systems of the lettuce be removed from the plot and destroyed, in order to avoid enriching the soil with plant debris and chlamydospores.

Note that no fungicides are registered for use Thielaviopsis on on salads.


- Next crop

In the nursery, it is important to use healthy substrates . Plants produced in mini-clods should not be placed directly on the ground, especially if the latter has not been disinfected; a plastic film will have to insulate them. Preventive treatments are sometimes carried out in the nursery with the products mentioned above. We also advise you to apply the hygiene measures recommended in the chapter on Sclerotinia spp .

Of crop rotations will have to be implemented imperative to prevent an increase in the inoculum levels of the soil. To be effective, they will be long enough, at least 4 to 5 years, and must not involve sensitive crops. Thielaviopsis basicola has been described on many plants: vegetable crops previously reported, field crops and industrial productions (cotton, peanuts, soybeans, alfalfa, lupine) and various ornamental plants (chrysanthemum, pelargonium, etc.). The strains of Thielaviopsis basicola isolated from lettuce are obviously polyphagous, but their host range is not always known precisely. Species reported are only an indication. Cereals are a good precedent, as are rice and sorghum.

A soil disinfection * may be considered under shelter with a fumigant (dazomet) ( e-phy ).

Tools used for tillage of contaminated plots should be thoroughly cleaned before being used in other healthy plots. It is the same for the wheels of tractors. Thorough rinsing with water and disinfection of this material will often be sufficient to rid it of soil and Thielaviopsis basicola .

The drainage of the plots, the fertilization of the plants, as well as their irrigation will be perfectly controlled; it will be advisable to maintain the pH of the soil around 6 and not to over-lime it. It will be necessary to be wary of certain organic matter brought to the ground.

The differences in sensitivity between lettuce cultivars were observed in Australia (Monaro, Kirrali, Centenary would be insensitive).


* As the number of pesticides available for a given use is constantly changing, we have nevertheless chosen to indicate in each sheet the name of a few active ingredients approved at the time of writing. We will try to update this list, as withdrawals and new approvals occur. Despite this, 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.