Saint-Marcel-lès-Valence (France) (AFP)
The intelligence of nature at the service of fruit production? INRA tests in the Drôme an organic experimental orchard, where each tree species defends its neighbor against pests or fungi, hoping to have a day of chemicals.
Built in concentric circles in Gotheron in the municipality of Saint-Marcel-lès-Valence, the orchard of one hectare and a half was established in February 2018 and will give its first fruits in 2020 at the earliest. The experiment should be spread over fifteen years.
No more uniform fields and repetitive rows of single varieties of apricot or plum trees, the Institute of Agronomy has from the outset bet on diversity.
The round shape is intended to protect the production, to "make sure that the bio-aggressors have difficulty to reach the trees of the center", explains Sylvaine Simon, assistant director of the site.
Psyllids, aphids, flies and greedy caterpillars that target flowers or fruits, but also diseases transmitted by spores or microscopic fungi must not be able to move or multiply.
So we must deceive nature and use it: it is bioregulation. The outer circle is a plant barrier composed of tall trees, chestnut or walnut trees, which act as windbreaks, and low shrubs that serve as a shelter for rodents or birds.
The second circle is composed of trap plants, early apple trees (Flora-Akane variety) and resistant ones. They will "fix" the aphids that would have managed to cross the outer hedge, shows Ms. Simon. As they produce early in the season, apples should not be overly affected by a possible "leafroller", a parasitic caterpillar that strikes in the middle of summer.
- Limit the installation of diseases -
Then comes a vegetable barrier of fig, hazel, pomegranate, loquat, persimmons, raspberry. These will prevent the leaves of the apple trees in the previous circle from migrating to the center. One of the apple diseases, scab, is spread by leaves fallen to the ground in the fall.
The next six spiral rows alternate with stone and pome fruit trees: apricot, peach, plum and apple trees. The rows are not uniform, a series of apricot trees next to a family of peach trees. The varieties are hardy and not susceptible to pests and diseases.
If by chance the mushroom "monilia", which attacks the apricot blossom, develops, it could not affect more than four or five trees at a time, since the neighboring peach tree does not fear it. Same thing for fishing, whose "blister", another mushroom, leaves the apple tree of marble.
"The idea is to limit the installation of diseases" says Solène Borne, INRA.
Bat shelters are installed to get rid of unwanted insects. "If you have too many aphids, you will be sowing fababeans outside the circle," she says. It is a legume that attracts aphids and diverts ants.
To overcome voles that proliferate and damage the roots, perches have been installed to attract raptors.
Alfalfa, sown inter-row, is intended to fertilize the soil. This plant has the particularity of capturing nitrogen from the air and transmitting it into the soil, thus avoiding the use of chemical fertilizers.
"We look at who eats who, and we look for what we can expect from plant diversity in terms of disease regulation," Sylvaine Simon explains.
This scientific project also has a professional purpose. Everything has been planted and is mechanically exploitable.
This orchard is part of a vast program of studies on the scale-up of organic farming, announced by INRA at the Tech and Bio show in Drôme last week.
It is already emulated in this fruit region. "I also alternated trees," said AFP Bruno Darnaud, president of the AOP Fisheries and Apricots. "Before I did not care about all that, bats, birds ...".
© 2019 AFP