CropsBiology, epidemiology
- Conservation, source d'inoculum
The winter storage in the vineyard of the viruses involved takes place in the infected vines, and possibly via the vector insects which would survive the cold. Already affected plots located in the immediate vicinity of the vine can also serve as sources of inoculum via vectors from spring.
With regard to newly planted plots, the plant material, if it is not certified, can carry viruses and be the source of the first contaminations. This is particularly the case for rootstocks, sensitive to viruses but asymptomatic.
- Transmission and dissemination of viruses
The coil can be transmitted and disseminated in two ways:
- by the plant material used for the vegetative propagation of the vine and by grafting: rootstocks and scions;
- by several species of cochineals * present in vineyards in France (for at least 2 of the viruses associated with leaf roll: GLRaV-1 and GLRaV-3): two so-called mealy species Heliococcus bohemicus and Phenococcus aceris, and two shelled species, Parthenolecanium corni and Pulvinaria vitis (Figures 1 and 2). The GLRaV-2 vector is not yet known. The transmission of viral particles is ensured during the feeding activities of these insects which feed on the sap of the phloem. Once inoculated into the vine, leaf roll viruses multiply mainly in the conductive tissues, impeding the flow of sap.
Note that these viruses are not transmitted mechanically during pruning and harvesting, or by contact.
* Some other vector cochineal species reported in the world : Pseudococcus affinis , P. calceolariae , P. longispinus , Planococcus citri and P. ficus , Parthenolecanium persicae , Neopulvinaria innumerabilis, Ceroplastes rusci.
Bibliography
Le Maguet J (2012) Epidemiology of viral rolling of the vine in northern French vineyards and transmission by vector mealybugs . Thesis of the University of Strasbourg
Cassagnes J (2013) Leaf roll virus - A disease that is spreading in France and which worries researchers . Le Mel Viticole n ° 153, 05/17/2013