CONTROL OF WALNUT HUSK FLY USING ALTERNATIVE METHODS

The walnut husk fly (Rhagoletis completa Cresson) was observed for the first time in the South-East of France in 2007. In highly infected orchards, this quarantine organism can damage up to 80% of the annual production. In 2008, a network of orchards was monitored and experiments were set up in order to; (1) follow spatial propagation and (2) assess husk fly management techniques. Six different substances were tested, focusing on non chemical products. Four of them are in accordance with the specifications of organic farming. Two commercial products composed of kaolin have been tested. Treatment consists of a suspension of clay in water, sprayed on the whole canopy. This method has been successfully used to control cherry and olive fruit flies. The clay deposited on the walnut husk forms a physical barrier which should prevent oviposition. Two plant protection products containing Spinosad have also been tested: one in the form of bait, the other sprayed as a classic insecticide. Moreover, five kinds of traps have been tested and the most efficient could be studied in order to validate a massive trapping programme in low fly density situations. The results concerning the efficacy of the different control methods and the spatial propagation of the walnut husk fly in 2008 are presented and discussed.