Damage is most severe during early crop establishment, with effects including the stripping of cereal shoots and leaves. HGCA work has confirmed that every slug can kill up to 50 wheat seeds in the first week of sowing, with smaller slugs killing more seeds than larger slugs.
Oilseed rape is a significant crop severely affected by slugs, with yield losses potentially exceeding that of cereals where emerging seedlings are most vulnerable, in some cases leading to complete crop wipe out.
The risk of slug damage increases following wet summers, with slugs also favouring incorporated straw and crop residues which provide sufficient plant material to maintain and encourage pest populations between crops. Trials conducted during a dry autumn have shown that 35% of early cereal plants can be damaged by slugs, rising to over 50% in wet conditions.
Species such as the common, grey field slug (D. reticulatum) provide a particular risk due to its fast breeding rate which can occur at any time of the year.
Mild winters and wet summers coupled with current cropping practices means the problem of slugs is likely to increase, continuing the need for effective control. Therefore, the economic implications of losing metaldehyde could prove severe within arable production, with significant crop damage and yield losses. Due to the active ingredient’s significance it is vital that best practice guidance is followed and the adoption of immediate changes to current practices is observed to prevent contamination and ensure the continued use of metaldehyde.