Slugs poised to hit vulnerable crops |
 | Growers in the south and east have been advised to stay vigilant as high value wheat and oilseed rape crops struggle to establish in parched soils. Poor seedbeds have left crops very vulnerable to attack from slugs.
Hutchinson technical manager Dick Neale describes crops as a “mixed bag”, with a relatively low proportion of ideal, fine, firm seedbeds. “Some rape sown in September is struggling, and some crops have already been lost to slugs,” he reports.
“The main worry is wheat that has recently been drilled into heavy, cloddy soils. These will need a good dose of quality slug pellets as soon as it rains. Don’t wait until you see damage because it will be too late. Then growers must remain vigilant and monitor crops for further signs of damage.”
Slug activity on the dry surface is currently low. But there are uncommonly large populations lurking in moist soils beneath. These won’t need much encouragement to come to the surface, says Markus Bieri, technical manager with Meta-metaldehyde manufacturer Lonza.
“Growers should keep a close eye on field conditions. In autumn, as the temperature drops, experience suggests the first fogs or early morning dew can be enough to increase slug activity,” he explains.
“But it is crucial that quality Meta-metaldehyde pellets are applied. These will give you around three weeks protection, even in wet conditions. Poor quality pellets will disintegrate as soon as it rains, which is when you will need them to do their job.”
Growers should choose pellets that carry the Meta Quality logo, such as those made by Certis and De Sangosse. These have been manufactured to a minimum quality standard that ensures they last in wet conditions, spread well and are palatable to slugs, Mr Bieri points out.
“And metaldehyde has the added advantage that it is a specific molluscicide. That means beneficial organisms, such as earthworms and carabid beetles, remain unaffected if they come into contact with it.”
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The rain has brought the snails out |
| Last year's slugs and snails and their eggs have survived the mild winter unharmed and this year's dry April has also left them unscathed. With the onset of rain in May they are now searching all the more hungrily for food. This may have unpleasant consequences for gardeners and farmers, warns Thomas Schuster, an agricultural consultant and snail expert at the Bavarian Agriculture and Forests Office in Augsburg, Germany. Young snails need to eat fresh green foliage now in order to mature, while older snails have to build up their strength to lay more eggs. All this can only mean one thing, says Schuster: snail damage to vegetables, ornamental plants and strawberries.
In addition to taking preventive action, it is also a good idea to put out slug pellets between ornamental plants and strawberry beds or even in greenhouses.
The majority of modern slug pellets contain the active ingredient metaldehyde, explains Schuster. This substance is particularly fast acting and retains its potency for up to ten days even in wet weather. Moreover, since it only attacks snails' mucus-producing cells, it poses no threat to hedgehogs, ground beetles, birds or other natural slug predators. Metaldehyde does not pollute the soil since it degrades into natural substances.
Slug pellets should always be distributed evenly between beds. Only a few metaldehyde-containing pellets per square meter are sufficient for rapid and effective slug control. |
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