The use of chemical pesticides in agriculture is a highly contentious topic, provoking powerful emotions from environmentalists, consumer groups, politicians, and the agricultural community.
Last month, I wrote about the French EcoPhyto program and focused on steps that can be taken to reduce the risks of pesticide use. This month, I will focus on how winegrowers They are reducing their use, either by reducing the amounts used or by finding alternatives.
When it comes to reducing dependency on pesticides, winegrowers You have several options, starting with choosing and maintaining your spray equipment.
Regulate use to avoid waste
A good sprayer will be much more efficient in the use of the product than a poor one and that can make a big difference in the amount of pesticide that is used and in the amount that is sprayed on the ground or in the air, rather than on the vine. .
A new generation of sprayers have been developed that recover missing sprays from the vines, although these are only really suitable for flat and trellised vineyards.
In the last 10 years a system of control and certification of vineyard sprayers has been implemented to ensure that they are well maintained and calibrated to avoid leaks, accidents and to ensure that the desired dose is actually sprayed.
Understanding the level of threat that disease and insects pose to each vineyard at each stage of the season can reduce the amount of pesticide used by up to 80%. For example, it is not necessary to apply the full dose of a pesticide when the vines only have small shoots.
Also, you don’t need to start spraying to protect yourself from downy mildew before it rains or when temperatures are still low.
Insects have known life cycles and tracking their activity allows insecticides to be sprayed at precise times, avoiding waste and risks to beneficial insects, especially bees.
Respecting the ecosystem cycle
I know older winegrowers They used to spray the same pesticide mix every two weeks during the growing season.
The Ecophyto program has done a lot to get rid of that mindset. Some grape varieties are more resistant to powdery mildew than others. Some have tight clusters that harbor disease.
Overuse of fertilizers will make a vineyard overly vigorous, with many leaves providing moist, shady conditions that are conducive to fungal diseases.
Choosing where and how densely to plant vines and what trellis and pruning methods to use can make vineyards less susceptible to disease and easier to protect with fewer pesticides.
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New disease tolerant grape varieties have been developed and approved for most French regions, although as far as I know none are allowed for appellation wines.
Whether consumers choose those wines over traditional ones is another matter. Maybe if they appreciated the reduction in pesticides, they would. Biocontrol products can be used as alternatives to insecticides.
Trichogrammes are tiny parasitic wasps that attack the eggs and larvae of the grape moth. However, spreading them is expensive and they cannot be doused with sulfur.
Bacillus thuringiensis bacteria have insecticidal properties but are incompatible with copper-based fungicides and require twice as many treatments to cover the life of the larvae it kills.
Sex confusion pheromones can be dispersed to prevent mating by harmful insects, but they are expensive and less effective than insecticides.
Yes to natural treatment, but not just any.
Some winegrowers I swear by their “natural” treatments like nettle teas and ready (horsetail), but scientific trials show no significant protection against fungal diseases.
However, they can improve the effectiveness of pesticides (organic and synthetic), thus reducing the required dose. When it comes to reducing herbicide use, mechanical alternatives offer the best solution.
A new generation of sensor-controlled plows has been developed that can work under the row of vines.
Other options, like gas powered weed burners, are ineffective and polluting in their own way. Acid-based herbicides are considered too ineffective in a vineyard.
The widespread use of herbicides should be replaced by a combination of plowing and row planting with cover crops that do not compete with the vine for water or nutrients, and that also act as a source of organic matter.
By taking a holistic approach to improved growing methods, using the best spraying equipment, choosing the least toxic products and taking proper care when handling them, using alternatives whenever possible and moving towards disease tolerant grape varieties, it can be reduced the use of pesticides in viticulture. at a sustainable level.
The approach won’t satisfy everyone, especially political activists who would like a complete ban on all crop protection chemicals, but it will greatly reduce the health risks of vineyard workers and the impact on the environment.
Jonathan Hesford has a postgraduate diploma in viticulture and oenology and is the owner, vigneron and winemaker of Domaine Treloar in Roussillon.
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