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May 30, 2022 View:

French vineyards back in good shape after months of disease

After months of disease pressure, the vineyards in France are finally back in good shape.

Photo courtesy of: Le Wine Guest

On July 5, the first bunches of grapes began to show signs of color change in the earlier ripening regions of France. For those vineyards with no symptoms of the disease, this stage marks the end of the risk of powdery mildew in the grapes and the vines no longer need to be sprayed, so growers can put their minds at ease for a while.

However, for those whose leaves or bunches are already infested with the disease, they may need to be sprayed before turning color.

Powdery mildew, a fungal disease that affects a wide variety of plants, is a disease that affects mainly leaves, branch tips and fruit, with young tissues being the most sensitive. Infected plants show white powdery spots on leaves and stems, which become larger and denser as the disease progresses with the formation of large numbers of asexual spores, and the fungus may spread throughout the plant.

Every year, during the growth of grapes, there is a risk of attack by various diseases, powdery mildew being one of them. In addition to this, there is also downy mildew.

Grapevine downy mildew is a worldwide grape disease. When the disease is severe, the leaves scorch and fall early, the new growth is poor, the fruit yield is reduced, the quality is deteriorated, and the plant is poorly resistant to cold.

The disease originated in North America and was introduced into Europe in 1870 with the introduction of phylloxera-resistant rootstocks, which at one time caused very serious losses to the European grape industry.

The disease has been variable in French vineyards this year. Burgundy has been more fortunate in that the vineyards have been largely free of the disease.

According to the plant health bulletin, symptoms of downy mildew in grape bunches (in Burgundy) were few and far between, appearing only in four vineyards belonging to the monitoring network of the Sane et Loire and Jura regions of Saône-Loire.

This year"s weather has been generally mild for vineyards in northern France. But the opposite is true in Bordeaux and the Languedoc, where growers need to remain vigilant. A consultant from the co-operative winery institute (co-winery institute) stressed that various protection programs had to be introduced in these regions from April onwards to deal with downy mildew.

However, since the weather began to get hot and dry in early July, the disease has been relatively less severe. Plant Health Bulletin reports that we have seen very little change, with the frequency and intensity of affected bunches unchanged at 16 and 10 percent, respectively

If the rain stays in the bay, the risk of fungal disease in new vineyards is almost zero.

The situation is almost similar in the Languedoc appellation. Overall, the canopy looks good, but growers need to be wary of phoma, which can develop quickly this summer if it rains or there is morning dew, warns Laurent Duret, a consultant for ICVICV, the vineyard service.