15 March 2002

Control slug threat before planting crop

CHECK fields for slug activity before planting and if they are active take the chance to control them while you can, says an East Anglian-based independent agronomist.

"This is as good a time as any to put pellets on because there are fewer food sources," says Martyn Cox. "I dont believe in leaving high populations just to start pelleting at tuber initiation."

Controls later in the year may not succeed, he says. "Slugs are very difficult to control in a dry summer because they live under ground and in the tubers."

Any soil that sticks to your boots when wet is slug prone and multiple traps should be set to identify if slugs are active.

"Grazing can be quite localised and sporadic. You may have to look a lot of times before you find any. But if you do find any then you have got to be going on with pellets."

Mr Cox recommends that a durable pellet is used at this time of year. "I prefer the wet-processed pellets."

But timing is more important than product choice, he says. "Slugs have to be on the surface to find the pellets and they are not active on the surface at all times – wet, cool, damp weather is their favourite."

Field margins are particularly prone to attack and a closer watch should be kept on crops here. "Have a very good look before lifting. You may need to keep them separate."

Buyer demands will dictate which varieties are grown, but where possible growers should tweak choices so slug favourites, such as Marfona or Maris Piper, are kept away from the worst fields. "But they will have a go at any variety."

Once activity has been identified in a potato crop, keep pelleting until lifting, says Mr Cox.

"As the tubers bulk and form an increasing proportion of the ridge it becomes easier for slugs to find them. It is very important to keep up the pressure. You can lose an awful lot of potatoes in a fortnight." &#42

&#8226 Consider pellets pre-planting.

&#8226 Constant monitoring.

&#8226 Pellet from whenever active.

&#8226 Do not stop until lifted.

Are slugs leaving a hole in your potato profits? Martyn Cox suggests an early start to control.

Opportunity knocks

If potatoes are part of your rotation every opportunity in every crop should be taken to combat slugs, suggests Mr Cox. "If they are active in wheat at flag leaf and you know you will be following with potatoes, then have a go at them then." Similarly volunteers in stubbles should be checked for grazing before spraying off and ploughing. "If slugs are active then put some pellets on with the glyphosate." Where land is rented for potatoes make arrangements with potential landlords to limit the slug risk in advance, he adds. "Try not to think of slug control as a cost to any one crop – it is a cost across the whole rotation."