This press release is available in Spanish.
Scientists at the Basque Institute of Agricultural Research and Development, NEIKER-Tecnalia, and the National Institute of Agricultural Research in Bordeaux (INRA) have come to the conclusion that alleged symptoms of 'black dead arm' (BDA) on grapevine leaves are, in fact, those of esca disease in its initial phase. Esca and BDA are diseases that affect the trunk of vines and cause serious losses to the wine-making and grape-growing sectors every year.
The symptoms produced by esca and BDA in vine leaves are reminiscent of those of drought. In the case of esca, the tissue between the veins dries up and appears surrounded by a red pigmentation and then another yellow discoloration before reaching the green, fresh tissue (tiger stripe pattern). The leaves which to date were believed to be affected by ''black dead arm" (BDA) only showed the red pigmentation beside the green tissue. This difference led some researchers to believe that two different diseases were involved.
With the goal of studying these signs more deeply, NEIKER-Tecnalia and INRA researchers undertook a fortnightly monitoring of affected vines over a period of three years, at a number of vineyards in the Rioja Alavesa (Spain), Bordeaux (France), the Rhine area (Germany) and the Bekaa Valley (Lebanon). The experts observed that the leaves progressed from the so-called BDA symptoms to those of esca, and even that both symptoms could be detected at the same time in many of the plants studied.
If two different, independent diseases were involved, most of the vines would show external signs of either BDA or esca; but not of both succesively.
Thus, the specialists concluded, both the leaves showing red markings and yellow ones beside the green tissue, as well as the ones showing red markings only, were affected by esca. Mo
|Contact: Aitziber Lasa Iglesias|