Reduced applications of metaldehyde pellets for reliable control of the slug pests Arion lusitanicus and Deroceras reticulatum in oilseed rape adjacent to sown wildflower strips.
Abstract
The possibility of preventing severe slug damage to oilseed rape by applying metaldehyde solely on wildflower strips adjacent to the crop was studied. Metaldehyde in 20 or 40 kg/ha applications was sprayed on 50 cm wide barriers along weed strips and 10 kg/ha was broadcast over whole rape fields near Bern, Switzerland in autumn, 1996. Untreated control plots suffered severe crop loss at 1 m from wildflower strips. All molluscicide treatments prevented severe crop loss without significant differences between the 3 treatments. Arion lusitanicus and Deroceras reticulatum were the most abundant slug pests found in the rape fields. A. lusitanicus was very abundant in the wildflower strips and up to 1 m into the field, but was almost entirely absent 3 m from the strips. D. reticulatum was evenly distributed over the whole field area. It is concluded that A. lusitanicus was responsible for the majority of damage in control plots 1 m from the wildflower strips. The application of metaldehyde in a 50 cm wide band effectively prevented severe slug damage to rape near wildflower strips. This method reduces inputs of chemical molluscicide and saves time and money for farmers.