T39R4Q7F

9910

9 avril 2021 17:30

6 mai 2024 10:30

The main objective of those trials was to determine alternatives to massive copper utilization to control potato late blight (Phytophtora infestans (Mont.) de Bary) in organic systems. To reach such a target, we first performed a screening of candidates products and additives under controlled conditions in the laboratory. Thereafter, the most promising products were tested in the field in 2006. Those trials were set up in three different sites, two sites in Belgium and one site in France. Herseaux (B) and Loos-en-Gohelle (F) are situated near by see level in an important potato culture basin with silty soil. Libramont is located at 500 m of altitude, far from any potato culture basin, with a sandy - loamy and stony soil. The cultivar Ditta was used in Belgium while the cultivar Juliette was planted in France. Their resistance to foliage late blight is, respectively, medium and medium-high. In total 8 modalities were compared. The products were applied in accordance to the advice of the local late blight warning system. The control was sprayed, at each advice, with 3kg/ha of copper sulphate (Bordeaux mixture). We tested two additives to Bordeaux mixture, used at the 3kg/ha rate as well, the first one is a short chain amino-acid extract, used to enhance rainfastness, while the other one is an hydrogen peroxide stabilised with an organic molecule. This second product was used for its disinfectant effect added to the protection effect of copper sulphate. We also tested the efficiency of a formulation presenting a low copper concentration (Glutex CU 90 with 10% copper) and of an association between a potassium phosphite and a copper tallate (Solucuivre with 5% copper). Those two components were also evaluated separately. Finally, we tested a product containing rhamnolipid biosurfacant (Zonix) supposed to physically destroy the zoospore’s membrane. The 2006 climatic conditions were very particular. June and July were very dry while August was very wet with optimum late blight development conditions. The disease development was very slow during July and radically increased during August. The two additives tested didn’t improve the efficiency of Bordeaux mixture. The association of potassium phosphite and copper tallate gave good results. Separately, both products gave good results excepted the copper tallate in the site of Libramont. The formulation with low copper concentration as the rhamnolipid biosurfacant allowed an as good crop protection as the Bordeaux mixture modality. Given the particular climatic conditions of 2006, those products have to be tested an additional year to confirm their efficiency.

None

• AB - Spécifique
• CRA-W
• FREDO lutte
• FREDO santé végétale
• GEO Belgique
• GEO Wallonie
• copper
• cuivre
• fungicide
• helicitor
• late blight
• maladie
• mildew
• mildiou
• pesticide
• phosphite
• pomme de terre
• rhamnolipids

PPO-Special Report

12

7

27/07/2007

27 juillet 2007