Based in Machecoul, south of the Loire-Atlantique, the Scea Vendéa company produces lamb’s lettuce, young shoots of salad and radishes. In summer, 30 ha of large plastic greenhouses are assigned to the lamb’s lettuce. Light and heat become an issue. “Shading the greenhouses in the summer is necessary to limit the direct radiation on the lamb’s lettuce, which is sensitive to sunburn, to control the temperature and prevent too fast dehydration of the soil,” explains Denis Clavier, production manager at Scea Vendéa. “Another essential aspect is that a good shading of the greenhouses makes it possible to limit the problems related to Thielaviopsis basicola.”
Thielaviopsis basicola affects lamb’s lettuce crops
Appeared in the region about fifteen years ago, Thielaviopsis basicola is a telluric pathogenic fungus responsible for root necrosis and loss of population. Present especially in summer, high soil temperatures and moisture around the roots favor this fungus. Under large plastic greenhouses, up to 20% of producers are affected by black root rot, with sometimes sharp declines in yield. “Crop rotations are important to fight against Thielaviopsis basicola,” notes Denis Clavier. “But Shading, which makes it possible to adopt a drier crop which helps to prevent the fungus, is also essential.”
Sudlac Eclipse LD² shading recommended for lamb’s lettuce crops.
The Departmental Committee for Vegetable growing Development of the Loire-Atlantique French region (CDDM) provides technical support to vegetable producers from the Nantes Area. During a two-year study (2015 and 2016), they’ve been testing different Shading solutions on large plastic greenhouses for shading rate, resistance, and application. They concluded Eclipse LD² from Sudlac is the best product and they do recommend to get 50% of shading at the first application early in the season and then increase to 60-65% of shading at the second layer for lamb’s lettuce growers.
Following the CDDM recommendations, Scea Vendea applies each year the first layer of shading coating by helicopter onto its greenhouse around mid-April and then the second layer around mid-May. For two years, SCEA Vendéa uses the Eclipse LD² product. “Our goal is to have a quality coating and to not have to worry all season regardless of the climate,” says Denis Clavier. “We chose the Sudlac product Eclipse LD² based on the CDDM monitoring and feedback from the helicopter applicator who can judge the quality of the application. Eclipse LD² adheres very well to plastic and has a very good performance over the time. In 2017, there was a lot of rain in July. The shading measurements showed that there was no degradation of the shading due to the rain, which was not always the case with other products before. Production has also been enhanced. Since we are using Eclipse LD² and we’re following the recommended shading percentages, we have fewer problems with Thielaviopsis basicola, which means more productivity. The lamb’s lettuce is also firmer and less elongated.”