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Protection methods

- During cultivation

No curative method makes it possible to fight against the cucumber mosaic virus ( Cucumber mosaic virus , CMV) A plant reached will remain all his life.

Generally, the elimination of the virus-infected plants at the very beginning of an epidemic can help to slow it down; the difficulty of observing characteristic symptoms of CMV in lettuce sometimes makes this practice illusory. In addition, since the symptoms do not appear until a fortnight after contamination of the plants, the salads during incubation may constitute a source of virus and participate in the development of the epidemic.

Of Aphicides treatments are essential to control outbreaks of some aphids on lettuce. They are generally ineffective in controlling the development of viral epidemics. In fact, vector aphids frequently come from outside the plot and can transmit the virus even before the aphicide has time to act.

- Next crop

A set of measures should be implemented which will aim to prevent or at least limit as much as possible the introduction of the virus and its spread in the lettuce plots.

In countries where contamination is very early, it will be necessary to protect nurseries and young plants . For this, we can use agrotextiles (non-woven sails, mesh fabrics, etc.). The mechanical barrier thus created will delay contamination.

A weeding careful nurseries, plots and their surroundings (edges of hedges and paths ...) will be carried out to eliminate the sources of viruses and / or vectors. It will be necessary to avoid setting up a salad crop near crops more sensitive to CMV, such as tomatoes, spinach, cucurbits ... Crop rotations may be considered in production areas where the pressure of surrounding infected weeds is important.

In Great Britain and Germany, as in the United States where the virus can lead to significant losses, studies have revealed varieties with less susceptibility to CMV, but no really effective resistance has been found in Lactuca sativa .

In contrast, monogenic dominant resistance was identified in an accession of Lactuca saligna and introgressed in lettuce in the United States. Unfortunately, this resistance is specific to a few strains and has already been circumvented. Other accessions of Lactuca saligna and Lactuca serriola have been shown to be tolerant. The accumulation of the different genes involved in these tolerances would probably constitute the real solution to effectively control CMV. In addition, Lactuca virosa is believed to also have resistance to this virus.

NB: Controlling insect populations on a crop implies, depending on the situation, the use of insecticides. As the number of insecticides available for a given use is constantly changing, we advise you to consult the e-phy site of the Ministry of Agriculture and Fisheries which is an online catalog of plant protection products and their uses, materials. fertilizers and growing media approved in France. This also applies to all biological products based on microorganisms or natural substances.

Last change : 04/27/21