Are Slugs Damaging My Raspberry Canes and Fruit?

Slugs are not the most serious raspberry pest — established canes with their woody bark are largely resistant to direct feeding damage — but they can cause two specific types of problem. In early spring, young raspberry suckers just emerging from the soil are soft and vulnerable to slug feeding at soil level, causing the top to wither and die. During harvest time, slugs can feed on ripe or fallen berries at the base of the row, particularly during wet summers. In gardens with very high slug populations, both problems can be significant.

Protecting young suckers in spring

New raspberry canes emerging in spring are most vulnerable in the first few centimetres above soil level. Keep the base of the row clear of dense weed or dead material — slugs shelter in debris and venture out at night to feed. Applying wildlife-safe ferric phosphate pellets around the base of the row in March and April gives targeted protection during the vulnerable establishment period. Nematode treatment (Phasmarhabditis hermaphroditis) applied to moist soil in late spring provides season-long biological control.

Slug damage to fruit

Ripe raspberries at or near ground level and fallen berries attract slugs, particularly in wet summers when fruit cannot dry between showers. Fallen berries should be removed promptly rather than allowed to accumulate on the soil beneath the row. Raising soil level slightly with a mulch and ensuring the bottom of the row is well ventilated reduces the humid conditions slugs prefer.

Physical barriers

Copper tape around individual raised bed edges has modest deterrent effect. The most effective method for high-pressure gardens is habitat reduction — clearing long grass, weeds and debris from around the row eliminates slug shelter and reduces night-time activity significantly.