Virus de la pomme de terre : épidémiologie, détection, systèmes d’aide à la décision

Context

In potato seeds multiplication, potato viruses are among the most dangerous infectious agents. The majority of them are transmitted to the plants by very common vectors, the aphids (picture 1). The seed production is subjected to strict plant health controls aiming at the respect of official infection standards. Being given the economic risk that the downgrading or even the rejection of the productions by the official control Service constitutes, the producers are pushed towards a more or less blind intense protection of the multiplication fields. A better understanding of the viruses transmission phenomenon and of the factors leading to the transmission can help to set up fighting systems less dependent on the use of pesticides.

Objectives

The objectives of this project are :

- Studies on PVY (Potato virus Y) , particularly on the different strains forming this potyvirus group: strains relative importance in the whole PVY population acting in our region, varieties susceptibility, mature resistance, vectors efficiency for the infection;

- Studies on the relations between the vectors activity and the risk of seed lots downgrading with the objective of building a system able to evaluate this risk during the cropping season, system based on aphids flight informations given by the suction traps of Libramont and Gembloux;

- Studies on the efficacy of mineral oils and insecticides applications to reduce PVY contaminations in the field;

- The follow-up of the general quality of the potato seeds production related to the main viruses acting in Belgium.

Expected results

- A better knowledge of the different strains acting in our potato seeds fields can lead to an adaptation and improvement of the control strategies fo a better sanitary quality.

- A better information to the growers regarding the real efficacy of insecticides or new active substances coming on the market takes part in the improvement of the control strategies and in the environment preservation .

- To improve the skills of the laboratory of virology concerning the detection of potato viruses.

Results obtained

- Internal infection sources generally constitute the starting point of PVY spreading in fields.

- The dynamic and the species composition of the aphids flights in our region are known thanks to the populations follow-up putted in place for more than 20 years. The influence of the climate, mainly the temperatures observed from December to March, on the intensity of the flights in the spring is known.

- The follow-up of the winged aphids populations by capture in "Rothamsted" type suction traps (photo 2) allows us to establish an infection pressure index for PVY which is a good indicator of the final quality of the potato seeds lots.

- Struggle against the dissemination of PVY must be based on the use of mineral oils.

- PVY represents more than 90% of the downgradings of the seed lots after the laboratory control, meaning that PVY is the main virus problem for the potato seeds production in Belgium.