On the blogby Alfred
December 12 2019

Diseases and parasites

by Sébastien Légasse

The management of vine pests and diseases is always relevant, in a context of widespread motivation for a conversion to organic agriculture. It must be understood that not all vineyards are submitted to the same conditions to be certified organic. The presence of animals, insects and other diseases are the daily life of winegrowers; all this management  occurs before they even have grapes at maturity. These problems can lead to a decrease in grape production which inevitably affects grape quality.  

Phylloxera is the one that has had the greatest impact on the history of the vine. It is an insect of North American origin that attacks vitis vinifera, the species that accounts for the majority of European vines. It was accidentally introduced into Europe in the 1800s. During one of its evolution phases, it feeds on the roots of the vines, causing infections and leading to a certain death of the plant within three years. The solution came from the origin of the insect. Since North American plants are naturally protected from the ravages caused by the insect, the winegrowers have grafted their vitis vinifera onto American roots, called rootstocks. Even if this operation is much more expensive, it preserves the aromatic characteristics of the grape varieties used in Europe, while being protected from phylloxera.  Areas not affected by this insect are now very rare, often protected by natural barriers such as mountains or deserts and sandy or volcanic soils. We can mention Chile and parts of Australia or Argentina as one of the few that are still preserved.

There are also a wide range of other insects, from mites to nematodes, that can damage foliage, roots and grapes. Among animals, birds can wreak havoc on grapes, hence the use of protective nets to shield them. Other animals are fond of grapes; the wild boar is one of them. It is not uncommon for producers to have to hire hunters to do some cleaning near the vines.

And that’s not all… don’t forget cryptogamic (fungal) diseases that are caused by a fungus or parasite. Downy mildew develops with heat and humidity; it attacks young bunches and directly affects the quantity of grapes produced. Good drainage and appropriate viticultural techniques can help to limit the damage. The powdery mildew of the vine affects everything green in the plant and affects the quantity and quality of the grapes, also leading to defects in the aromas. Black rot can also lead to the loss of almost the entire crop; the grape mummifies and is covered with pustules. Nothing more to say!

Recently, a few articles have questioned the “organic” use of Bordeaux porridge. This mixture of water, lime and copper sulphate is an antifungal agent used to combat mildew.

It is not so simple to produce grapes… and that’s not to mention the hazards of Mother Nature which, if all goes well, will make it possible to reach the maturity of the grapes and the harvest in good conditions. We can only cross our fingers!


Some suggestions this week:

 

Nicolas Grosbois La Cuisine de ma Mère 2018

Red wine, 750 ml

Code SAQ : 12782441  | Regular price : 22,55 $

Domaine Marcel Deiss 2017

Red wine, 750 ml

Code SAQ : 12185410  | Regular price : 31,75 $

Laurent-Perrier Alexandra Brut 2004

Champagne, 750 ml

Code SAQ : 13024917  | Regular price : 389 $

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