Trapping

Risk assessment and cultural control measures are closely interlinked.

There are four main elements:

1- Trap to assess slug activity during the period before cultivation.
2- Use trap catches together with other information to assess the risk of slug damage.
3- Reduce the risk of slug attack by cultivation and adjustments of drilling depth.
4- Monitor crops throughout the early susceptible growth stages

Traps are best used in moist conditions when slugs can be seen to be active. Traps used in dry conditions will not give reliable results.

Use of chicken-layers mash has been shown to be a good bait for traps.  Slug pellets must not be used for trapping.

Assessment & Strategy

Effective slug control is about planning a strategy - understanding the level of slug activity that might be present in your fields and implementing control measures accordingly. It's important to plan this strategy for the whole year, as slugs will be active for the throughout the growing period even if there are not obvious signs of surface grazing. A reactive control strategy - distributing pellets only after signs of damage - is ineffective and often too late. You need to be getting the slugs before they get your crop.

Trapping can be used to get an estimate of the slug population present. A trap can be a simple container, plastic sheet or tile placed on the soil surface under which chicken layers mash should placed for slugs to feed on slug pellets should NOT be used for trapping. Monitoring the number of slugs in the trap after a 24 or 48 hour period will give an indication of the slug population. Some agronomists advise that growers apply pellets if is as few as one or two slugs are found in the trap as those on the surface will just be a small percentage of the total number in a particular field.

If placing traps in dry weather treat results with caution. Slugs may not congregate under traps in such conditions, but this does not necessarily mean you don't have a slug problem.

However, it is important to remember that trapping results provide information about active slug population which is not necesseraly the same as total slug population.

a. Trapping for slugs in the preceding crop or prior to sowing the new crop can give valuable information on current population levels and therefore the degree of potential risk the new crop faces.

b. Place traps in suitable weather conditions using chicken layers’ mash or equivalent as bait. ( Do not use pellets as bait beneath traps)

c. For further information on trapping see the HGCA website (www.hgca.com). DeSangosse co-funded Project Report 393, examining best practice slug control in arable crops.