Following maize, wheat and rice, potatoes are the world's fourth-largest food crop. It remains an essential crop in Europe and is experiencing rapid expansion in southern and eastern Asia.
Susceptibility to Slug Damage
Varieties vary in their susceptibility to slug attack; more vulnerable types will need greater attention paid to slug control programmes.
Slugs thrive under the dense and humid canopy of the crop, but typical damage is to the tuber, rather than the above-ground parts of the plant. This makes spotting damage particularly difficult and the effects are often not noticed until harvest, when the damage has been done.
The longer tubers are left in the ground, the greater the risk of attack.
Research from Teagasc in Ireland showed that with the variety Maris Piper later harvest resulted in greater damage: lifted on 8th August - 10% damaged; lifted on 3rd October - 30% damaged; lifted in early November - 45% damaged
Heavy soils pose particular risk, as do already damaged tubers (e.g. through disease).
Species of Concern
Three species of slugs attack potatoes: Deroceras reticulatum, Arion hortensis, and Tandonia budapestensis. The black slug may also prove a problem, although it tends to favour leaves and stems rather than the tuber.
Symptoms of Attack
Slugs can damage potato tubers from late summer to autumn.They make round holes in the potatoes skin and will also tunnel out extensive cavities inside the tubers. Symptoms above ground are usually limited to noticing the characteristic slime trails. Tubers damaged by keeled slugs will often be more susceptible to wireworms.
Use trapping methods to assess populations and if thresholds are met, then broadcasting pellets immediately after drilling is likely to provide the best control.
An even distribution is important to ensure slugs come into contact with pellets as soon as possible. Calibrate your equipment carefully
Following application, continue to monitor crops throughout the critical early stage, when they're most susceptible.