• Logo_picleg
  • Quae

Protection methods

The fight against the virus of Western beet yellows ( Beet western yellow virus , BWYV) is very difficult given the large number of plant species likely to be infected, the persistence of the virus in the vector and the relative abundance of vector aphid species .

- During cultivation

No curative method can fight against BWYV . An affected plant will remain so throughout its life.

The Aphicides treatments are essential to control outbreaks of aphids on lettuce. They are generally relatively effective in controlling the development of epidemics of this virus if they intervene preventively, thereby helping to reduce aphid populations in crops and in their environment. Once summer jaundice is well established in the crop, it is often too late to intervene effectively.

- 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.

Although removing the source plants seems unrealistic, weeding careful in and around salad plots will limit potential sources of viruses and vectors.

In production areas where salad crops are spread out over time, in contiguous plots, the frequency of infections will gradually increase.

Given the fairly long incubation period (3 to 4 weeks depending on the stage of infection) which separates lettuce infection and symptom expression, any delay in plant contamination will reduce the extent of damage. This is because plants infected late in their vegetative cycle will show symptoms on a reduced number of leaves. A light trimming will allow the salads to be marketed .

The limitation of aphid populations through the use of insecticides , outside and in the parcel or parcels, help reduce outbreaks. On lettuce, a plant on which residue problems are particularly sensitive, the range of insecticides with a certain persistence should be used with discernment and in accordance with the recommendations of the manufacturer and your technician.

Extensive varietal screening work, involving hundreds of lettuce genotypes, has been carried out by several research teams. It has not made it possible to demonstrate high-level resistance. All the same, it emerges from this work that batavias and icebergs are less sensitive than romaine or butters . It also appears that differences in sensitivity exist within each of these types.

In addition, it should be noted that crosses between varieties resistant to bolting (America type, very sensitive to the virus) and more blond spring varieties have led to summer varieties with less sensitivity .

A recessive gene " bwy " , conferring good tolerance to BWYV, has been identified in a variety of batavia and one of butter lettuce. In addition, a dominant gene, conferring quasi-immunity , has been identified in an accession of Lactuca virosa . Interspecific crosses have been undertaken and a number of progeny families are being evaluated.

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