Efficacy of pesticide seed treatment of oilseed rape to control slug damage

Abstract: Slugs are an important pest of oilseed rape. The most susceptible plant stages are fromthe start of germination until the second leaf has been formed. Damage results in open spots inthe field which can cause yield loss, weed problems and variation in ripening. Baitedmolluscicide pellets are predominantly used to control slugs often resulting in inadequate control.One laboratory experiment and two field experiments were carried out to test the efficacy of filmcoatingoilseed rape seeds to protect the crop against slug damage. Treatments were comparedwith an untreated control as well as a reference treatment in the field experiments consisting ofbroadcast applications of metaldehyde slug pellets at a rate of 448g a.i./hectare. In conclusion,metaldehyde showed sufficient protection of the crop against slug damage at rates from 80ga.i./kg seed upwards and thiacloprid protected the oilseed rape from rates of 38.4g a.i./kg seedupwards. Results of imidacloprid were variable showing good protection in 2006/2007 only. Theremaining pesticides failed to protect the oilseed rape. Results are discussed with particular focuson the variation in results between metaldehyde and imidacloprid and thiacloprid.