Guignardia bidwellii (Ellis)  Viala & Ravaz 1892

Black rot, dry rot


Black rot, a specific disease of the grapevine, originates from North America where the responsible fungus was discovered at the beginning of the 19th century. It rages with more or less severity in all the vineyards of the world. This disease is of major economic importance in the northeastern United States, Canada, South America and parts of Europe. It was probably introduced in many countries via contaminated plant material, as was the case in France via rootstocks resistant to phylloxera.

Black rot was first described in our country at the end of the 19th century. It has mainly spread to the regions most favorable to its development, such as the South-West, the West and Savoy. The regions with summer drought, particularly in the south, have been and are more spared.

Although we do not have a precise assessment of the incidence of this disease in our country, attacks on leaves and twigs seem to be much more detrimental to grapevines in recent years. Black rot is above all a cluster disease which causes both qualitative and quantitative harm. Crop losses fluctuate depending on the epidemics which depend on the size of the inoculum, the weather conditions, and the sensitivity of the variety cultivated. Currently, black rot only occasionally poses problems in poorly managed and / or protected vineyards.

This fungus in its perfect form produces ascocarps (pseudothecia) in a stroma. Its imperfect form is referred to as Phoma uvicola Berk. & MA Curtis (1873) or Phyllosticta ampelicida (Engelm.) Aa (1973).

Several specialized forms of G. bidwelli have been described in the past: Guignardia bidwellii f. sp. muscadinii Luttrell pathogenic on V. rotundifolia and V. vinifera ; Guignardia bidwellii f. sp. parthenocissi Luttrell affecting only several species of Parthenocissus . This ancient work deserves to be taken up again using molecular tools in order to be certain that we are indeed dealing with the same species.
Last change : 04/26/21