Oilseed rape is vulnerable to grazing by slugs from the time of germination until the four true leaf stage. During this time, the crop should be inspected regularly using the method described below.
Recent trials have shown that the most effective way of controlling slugs is by taking preventative measures. Broadcasting onto the surface, after drilling, but before any slug damage has been detected, has proven to be a successful method, particularly in a wet autumn.
However, mixing slug pellets with the seed at the time of drilling is often ineffective as the seed and pellets are unavailable to the slugs.
Growers should endeavour to incorporate post harvest residue into the soil to increase the speed of decomposition of the residue and to reduce the source of food for any slugs. Growers should also endeavour to produce a fine firm seedbed that has been rolled after drilling.
Monitoring Slug Damage:
It is important to assess the likelihood of slug grazing taking place on the newly planted oilseed rape. Slug traps should be put out across the field in a "W" shape. Two heaped spoonfuls, per trap, of chicken layer's mash should be placed on the ground and then covered with a tile, slate, or plastic bag well secured with stones.
The traps should be left out overnight and inspected the next morning. A catch of one or more slugs per trap indicates a possible risk.
Growers should take advice from their agronomist or chemical supplier before applying slug pellets.
In addition growers should be aware of the "Pelletwise" campaign and ensure that pellets are not spread near water courses or into ditches.