The most known wood diseases are: Esca, Eutypiosis and BDA (Black Dead Arm). Several precautionary measures are to be taken in the conduct of the vineyard: mode and date of pruning, control of fertilization or water supply. Depending on the contamination, the affected vines must be uprooted or destroyed.
Symptoms for Esca, for example, appear on the leaves as early as July. Discoloration is seen between the veins of the leaves at the base and then throughout the branch. Then comes the rapid drying of the foot (a few hours or days) or apoplexy. In the wood, we notice necroses in places or central with clear and soft areas surrounded by brown areas.
These diseases are everywhere in Europe. In France, this concerns 40% of the vineyard with 10 to 15% of affected plants.
The contamination is carried out during wounds during the pruning of the vine which offers a door of entry to the mushrooms in the stock, particularly during mild and rainy winter. The time between pruning and contamination is time dependent. However, the biology and epidemiology of these diseases are still poorly understood.
A recent study confirms that mechanical pruning significantly reduces the problems of esca while reducing labor costs. The Chamber of Agriculture of the Gard has observed that there are 2 to 3 times fewer symptoms than with manual pruning using the Royat cordon. Other experiments report a 61% decrease in mortality.
One possible explanation is that mechanical pruning only cuts the current year’s wood, with few wounds on older wood when the machines pass. The zones of drying are more numerous but smaller, better compartmentalized which makes the plant manage better.
Nevertheless, mechanical pruning produces too much plant debris which can end up in the grapes and give undesirable tastes. In France, the AOC does not allow it! On the other hand, the IGP or Vin de France accept it.