Farmers combat resistant ray-grass with new methods

Farmers in the Bocage Nantais and Bessin regions of Normandy are using new agricultural techniques to manage resistant ray-grass, a weed that harms cereal crops. They are modifying their soil work and introducing triticale or mown grasslands to reduce the weed's impact. Triticale, a hybrid of wheat and rye, has shown better competition against ray-grass than wheat.

Triticale's advantages over wheat

Triticale grows taller and has a greater tillering capacity, which helps it outcompete ray-grass. In trials, triticale produced 4.5 tillers per ray-grass shoot, compared to 12 in wheat, according to Clement Chevalier, a network engineer at Dephy. Although triticale sells for less than wheat, its benefits include reduced use of mineral nitrogen and fungicides, and it can produce equivalent or higher grain yields and more straw.

Grassland management disrupts ray-grass cycle

Implementing a grassland for three years helps break the cycle of resistant ray-grass. Farmers are advised to choose complementary plant species to extend the competition period. Late sowing, between late September and early October, has been shown to limit ray-grass development before winter. Regular mowing, every five weeks before heading, helps prevent seed production.

Plowing and sowing strategies

Plowing to destroy the grassland is recommended to bury ray-grass seeds on the surface. In trials, no ray-grass was observed 20 days after wheat sowing followed a grassland period. The proportion of resistant ray-grass in the grassland cover dropped from 35% in the first year to 0% in the last year. These methods also provide balanced forage for cows.

Reducing plowing limits ray-grass growth

Reducing plowing helps keep ray-grass seeds deep in the soil, where they lose 90 to 98% of their viability after three years. Plowing only every three years can bury the last viable seeds. Farmers can also use non-plowed maize with mechanical weeding, ensuring good soil structure through cracking if needed.

Non-plowed maize and mechanical weeding results

In a Dephy trial, non-plowed maize combined with mechanical weeding was used for two consecutive years. Wheat was sown after plowing. After weeding, only one ray-grass plant was found per 3-4 square meters, compared to 14 in a control strip. This method involved good soil preparation, deep sowing, and mechanical weeding that destroyed most ray-grass.

Cover crops and mowing practices

A cover crop can be planted between non-plowed maize crops to maintain forage production for cows. Mowing must be done before resistant ray-grass sets seed. Forage cover with Italian ray-grass before maize is not recommended, as it can lead to regrowth and reduce the effectiveness of mechanical weeding.