Protection methods

- During cultivation

There is no curative control method making it possible to effectively control viruses, and in particular potato ( virus Y Potato virus Y , PVY) during cultivation. Usually, an infected plant will remain so for its entire life, although the symptoms sometimes tend to subside.

If attacks take place in the nursery, and they are detected early, the few plants showing symptoms of PVY will be quickly eliminated and in no case planted subsequently.

While aphicidal treatments * are often essential to control populations aphid on tomatoes, they are often ineffective in preventing virus epidemics. In fact, vector aphids frequently come from outside the plot and transmit the virus during brief bites, even before the aphicide has time to act. In addition, the difficulties currently encountered in controlling aphids on tomatoes, difficulties sometimes linked to phenomena of resistance to insecticides, do not help to improve this situation. It should be noted, however, that a certain number of auxiliaries make it difficult to control the population levels of aphids.

All weeds that can serve as virus reservoirs will be eliminated from the crop and its surroundings.


- Next crop

It is also advisable to recall all the measures which will aim to prevent or, at least, to limit as much as possible the introduction of PVY and its extension in the tomato plots.

In countries where contamination is very early, it will be necessary to protect nurseries and young plants ; contamination can thus be delayed by means of mechanical barriers such as non-woven sails or mesh fabrics. The production greenhouses of the plants can be made insect-proof .

A Careful weeding of nurseries , plots and their surroundings (hedgerows and roads ) will be carried out to eliminate the sources of viruses and / or vectors.

It will be necessary to avoid setting up a tomato crop near productions sensitive to PVY, in particular Solanaceae: potato, pepper, pepper, tobacco Remember that tobacco, potatoes, and to a lesser extent peppers, are likely to harbor various strains.

Spraying mineral oils plants with would reduce the incidence of PVY in crops. In fact, they would reduce the dissemination of PVY not by toxicity towards aphids, but by interfering with the attachment or detachment of viral particles on the stylet of the aphid vector. It should be added that the application of mineral oils is restrictive because the leaves must be permanently covered with a protective film on both sides, which requires regular and careful spraying.

The use of reflective mulches makes it possible to repel the vectors. In contrast, the yellow sticky traps favor the trapping of the latter.

In the case of viruses, the use of resistant varieties is often the most effective solution. Resistance has been demonstrated in Lycopersicon hirsutum 'PI 247 087' which has been shown to be effective against 36 strains or isolates of different geographical or botanical origins. Its resistance to PVY is efficient and stable under conditions of artificial inoculation or co-inoculation with the main pathogenic viruses on tomato. It is expressed both at low and high temperature, and with respect to concentrated inoculum. Two resistance mechanisms have been demonstrated:
-an inhibition of the accumulation of common PVY strains in the inoculated leaf. This resistance mechanism is expressed from the age of 12 days, but it can be bypassed by evolved pathotype strains (PVY LYE 84-2);
- partial inhibition of long-distance PVY accumulation and migration in the plant at the age of 41 days. This mechanism is expressed vis-à-vis evolved strains.

The resistance of 'PI 247 087' is said to be controlled by at least one recessive gene called " pot-1 ". Note that this progenitor also presents resistance to VTE.


* 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.