Risk factors

Even if traps catch only a fraction of the actual slug populations, they are an efficient means to detect and limit the presence of slugs.

The most commonly used trap measures 50 cm by 50 cm and consists of a plastic layer lined with aluminium foil where the slug is attracted by specific pellets. Placing 4 of these traps per field will indicate the degree of infestation of the plots.

For potato crops, the chemical control threshold level is 5 slugs/m2 at the beginning of tuber enlargement. However, chemical control by the application of slug pellets reaches only 40 to 70% efficacy, thus preventive measures for the whole rotation should be a priority for the control of slugs.

The choice of the potato cultivar is another alternative: field experience demonstrates that not all potato cultivars attract slugs with the same intensity. Trials on the tuber sapidity of different cultivars have shown that, with a highly infested plot, all the tested cultivars are attacked to a similar high degree. However, in less infected fields, some cultivars do not attract slugs at all (lack of sapidity), whereas tubers of susceptible cultivars like Monalisa can be completely destroyed.