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

Summary Slugs have been shown to cause severe damage in oilseed rape crops adjacent to sown wildflower strips. Rape can be protected from this damage by broadcasting a recommended dose of metaldehyde over the whole field area. This paper investigates whether severe slug damage can be prevented by applications of metaldehyde just along the wildflower strips thereby reducing the input of chemical molluscicide. In this study, untreated control plots suffered severe crop loss at 1 m from all wildflower strips studied. However, all treatments of molluscicide protected rape from severe crop loss without significant differences among the three treatments (two different concentrations of metaldehyde applied in 50‐cm wide barriers along the strips and a recommended dose of metaldehyde broadcast over the whole study area). Arion lusitanicus and Deroceras reticulatum were by far the most abundant slug pests found in the studied rape fields. Arion lusitanicus was very abundant in the wildflower strips and up to 1 m into the field; however, it was almost entirely absent at 3 m from the strips. Since D. reticulatum was evenly distributed over the whole field area, A. lusitanicus appeared to be responsible for the majority of damage in control plots 1 m from the wildflower strips. Application of metaldehyde in a 50‐cm wide band has been shown to be practicable and efficient in protecting rape from severe slug damage near to wildflower strips. These reduced applications of molluscicide mean savings of time and money for farmers and can be recommended for practical application.