At the Montreuil-en-Touraine contract gardens, a professional integration association around the market gardening, the winter harvests were somewhat turned upside down. At the foot of young shoots, chard and chews, small black mites on the red legs wander. No bigger than a millimeter, but can be distinguished to the naked eye, this mite called Penthaleus Major is harmful for cultures.
« He stings the sheet, which will create white spots. This depreciates the product, but above all its growth and development are slowed down »describes Anthony Sol, chief of culture. « We harvested much less than we hoped for. Because of this mite, accumulated in other factors, we had 10 % loss on the young shoot »he notes.
“He prefers fresh and humid conditions”
In recent weeks, several infections of Penthaleus Major have been identified in cultures from the Center-Val de Loire region. Clément Nivet, market gardener of Indre and used to the Amboise market, was particularly affected this year. « I have 8,000 m² of greenhouses. They are all infested. I have a greenhouse of spinach that has completely disappeared. In less than a week, mites have burst 600 m² »he testifies.
Touraine is for the time being more spared than its neighboring departments, with the sole case of infection identified in Montreuil-en-Touraine, according to the Chamber of Agriculture and organic Center Regional Association which brings together the actors of the sector agricultural.
« Those who are the most problematic in Indre-et-Loire are the tetranyque mites, who develop in dry and warm condition, therefore in summer. But two species annoy our cultures in winter. These are tyrophagus and penthaleus major », Share Eva Carriço, market gardening advisor to Bio Center.
« The Penthaleus Major Gradually emerges in our region for four or five years »notes the specialist. « He prefers fresh and humid conditions “she describes. Climatic conditions notably relevant in recent months.
-« It is a very polyphagous pest. It affects all leaves and develops particularly in a greenhouse »adds Édouard Meignen, market gardening advisor to Bio Center.
No approved treatment
Spinach, radish, carrots, beets … the Penthaleus Major propagates with ease on multiple cultures and chapels. Once there, it is difficult to get rid of it. « To date, there is no method identified to get rid of this mite »partage Eva Carriço.
« When a culture is affected, it is recommended to get rid of it, and to work the soil well to reduce the presence of eggs »recommends the market gardening advisor. « It is also possible to use a thermal weeder to burn herbs and mites on the surface, but that does not do everything »aweete
Advice followed by Anthony Sol in Montreuil-en-Touraine: “We made a crawl space. After the culture, a gas thermal weeder was used to limit invasions, then worked on the ground to break the laundry cycle of mites », he says. What limit the propagation of the mite in its culture, and even in the rest of the department.
Thomas Delaunay with Gaspard Mathé
