Wet weather brings slugs

The recent wet weather combined with the mild winter has increased the risk of slug damage to crops – particularly potatoes (Arable, 6 July) – and all growers should be extra vigilant when sowing this autumn, experts are advising.

“The weather has been suitable for slugs since mid-May,” says Styloma consultant David Green. “But the key will be what happens between August and September. If we get suitable weather, then numbers could increase rapidly.”

There have been some reports of slugs grazing up to the ears of standing wheat and crop consultant Mike Raynor suggests treating stubbles of some crops could be necessary. “We wouldn’t apply pellets in standing wheat as we don’t want to risk getting bits of pellets lodged in the ears. We might put some on rape stubbles if we can see a lot of slugs.”

Particular attention should be paid to land destined for oilseed rape this autumn as slugs can quickly wipe out crops from the cotyledon stage, he said. Close monitoring of problem areas and treating quickly is vital. “In wheat, the worst damage is from grain hollowing. We try to drill 1.5in (40mm) deep, which is below the depth slugs will go.”

The increased slug risk is illustrated on one of his customers’ farms, Philip Chamberlain at Crowmarsh Battle Farms in Oxfordshire. This year, just 37ha of the total 1200ha (3000acre) cropped area was treated with slug pellets, but for the 2007/08 season, he expects more than 300ha will need treating. “This autumn will probably be more like 2006, when we treated 320ha. The cropping hasn’t changed particularly it’s largely due to rainfall.”

Mr Chamberlain, who is a LEAF demonstration farmer, says targeting where pellets are required is a key part of the farm’s strategy, rather than blanket treatments. “We will highlight parts of a field that need treating and target those with the quad bike [and 24m spreader]. We don’t want to put pellets on, unless slugs are actually there.”

He is wary about applying pellets to stubbles, as surface trash may mean that they are kept out of reach of slugs on the soil surface.

paul.spackman@rbi.co.uk