S14 - Session P3 - Trunk injection of plant protection product to protect chestnut tree from fruit borers Cydia splendana and Pammene fasciana

Authors: Florence Verpont *, Adeline Renier, Nathalie Lebarbier

Cydia splendana and Pammene fasciana are major pest of chestnut in France. The fruit damage caused by the larvae can reach over 50% at harvest. Since the interdiction in 2011 of aerial spraying in France, the chestnut growers are in a technical impasse: conventional ground axial sprayers are poorly suited to the structure of chestnuts orchards (large volume trees). This leads to inefficiencies of the 3 or 4 treatments applied to control the codling moths. Trunk injection of plant protection products is a promising strategy to optimise pest and disease management in orchards. A first phase of prospective studies took place in France between 2015 and 2018 as part of a FUI project called Preamisse involving various models (ornamental trees in non-agricultural areas, vineyards, apple trees and chestnut trees). The demonstrations of effectiveness obtained in chestnut trees and the interest of growers encourage CTIFL (Centre Technique Interprofessionnel des Fruits et Legumes), the Centre for Expertise in Environmental and Plant Techniques (CETEV) and the experimental station Invenio to continue the work. The objectives of the study were 1) to evaluate the agronomic performance of different products applied by micro injection in the trunk to control Cydia splendana and Pammene fasciana in chestnut orchards 2) to assess the safety of this application technique with regard to the consumer (risk of residues on fruit). The trial included an untreated control and 3 plant protection products applied by micro injection in the trunk. A part of the plot included a sprayer reference (Karate Zeon, lambda cyhalothrine). Under the conditions of the 2020 experiment (high pressure: 61% of fruits were damaged at harvest in untreated plot), one of the micro injected plant protection product reduced significantly the rate of damaged fruit at the harvest by 63%. No residues were detected on fruits at harvest. From 2022, the new MISPA project will assess this application technique on other models: Gnomoniopsis castanea in chestnut orchards, Cydia pomonella and Rhagoletis completa in nuts and Pseudomonas syringae in kiwi.