18 September 1998

Slug slaying tips to beat autumn attack

Protecting crops from slugs,

rabbits, birds and bugs is

the goal of our autumn focus

on pest control. Over the

following pages we consider

monitoring, scaring and

baiting, giving you a timely

guide to best practice.

Edited by Charles Abel

MASSIVE slug populations threaten emerging crops everywhere this autumn.

A leading adviser in the north, who deals with this menace more than most, warns complete crop loss can result from complacency.

"Slugs are going to be a big problem," says Simon Francis, technical manager of the North of England Arable Centre. But this does not mean prophylactic pellet use is justified, and it could add an unnecessary cost. Control must start with cultural measures, he stresses.

"The first, and most important step in slug control is to get a good, firm seed-bed. Then chemical control may be left until after drilling, or even missed out completely," he says. But however good the seed-bed, this season growers should monitor slug activity, especially immediately before and after drilling.

"This is the most important time, as damage is underground and wont be seen until it is too late. At four slugs per bait point I would consider pelleting, and certainly dig to check for seed hollowing."

Continued wet conditions, plus the thick straw and trash this season, means a high carryover from huge pre-harvest populations. Newly-hatched juveniles will add to this, and if surface conditions remain moist, damage will be severe in unprotected crops, he warns. "In the worst cases, growers will have to re-drill."

Ideally, baits should be placed one every 2-3ha, but in practice a number located in potential problem areas will suffice. "Always bait in the areas of the field most at risk. These may be historically slug prone areas, such as where muck heaps have been, or patches where seed-beds are not ideal."

Regular monitoring, checking baits at least every 48 hours, is essential. Tiles, waited down bags, or purpose-made mats all make effective bait covers, he notes. "As long as it is dark and damp, and the bait has bran in it, it will attract slugs."

Non-pellet baits, such as broiler feeds, whilst reducing the risk to non-target species, are not advised. "The problem is the slugs come, eat, and then disappear. A pellet bait means they die and can be counted. And when checking traps, remove the slugs, so the count for the next 48 hours starts at zero," he adds.

Full rates of pellets are rarely justified, but stomach poison type pellets, such as methiocarb are more reliable in Mr Francis opinion. Their extra cost is particularly justified in a wet season. "But it is a very subjective area," he notes. "Mini-pellets (metaldehyde) do have the advantage of more bait points per sq m."

Baiting and monitoring should be repeated in two weeks after a dose of pellets, always with fresh baits. And the vigil should continue for as long as mild and moist conditions persist. &#42

SLUGS

&#8226 Fine, firm seed-bed first step.

&#8226 Trap to assess activity.

&#8226 Full rates rarely required.

&#8226 Re-trap 2 weeks after pelleting.

&#8226 Monitor so long as mild and wet.

Slug control starts with cultural control and can save growers the costs of mistimed application, says North of England Arable Centre manager Simon Francis. Huge carryover populations and high egg counts in the soil threaten all crops, making regular checks on activity essential.