Anti-slug benefit shows in cereal seed treatment

30 March 2001

Anti-slug benefit shows in cereal seed treatment

STRONG anecdotal evidence that a cereal aphicide seed treatment helps deter slugs has surfaced on the Kent farm of ACCS chairman Jonathan Tipples.

The difference between grain hollowing in winter wheat treated with straight Sibutol (bitertanol + fuberidazole) and a neighbouring field treated with Sibutol Secur, which includes imidacloprid insecticide, was remarkable, says Mr Tipples.

"Even to the untrained eye it was blindingly obvious." His observations, at Reed Court Farm, Marden, came after manufacturer Bayer approached him to sow Secur-treated Claire as part of an environmental monitoring exercise.

"We drilled a 30-acre field in late September and had ornithologists over from Germany for a week looking for things like bird carcasses. But we had also sowed 20 acres of Claire, treated just with Sibutol, the day before just over the road.

"Both fields had plenty of volunteer oilseed rape because it had been so wet and there were a lot of slugs about. Most of the volunteers were completely shredded."

Inevitably some grain remained on the surface and the absence of grain hollowing three days later in grains treated with Secur was very noticeable, says Mr Tipples. "It did not appear to kill the slugs – they just did not seem to like it and carried on shredding the rape."

By contrast most seeds on the surface of the smaller field were completely hollowed out.

"In cereals it is hollowing that is the real danger," he says. "We did not see any difference in slug grazing between the two fields."

There was also no noticeable difference in emergence levels between them. But precautionary half-rate mini metaldehyde slug pellets were applied down the spout in both cases, he notes.

Until last autumns experience the relative cheapness of cypermethrin as an anti-BYDV spray meant the Secur option had not been considered. "We had not really looked at it because of the perceived cost. But I shall certainly be tempted to use it later in the season where emergence is slower, although I will have to check out its clearance. I know you cant use it on broadcast seed."

Imidacloprids ability to deter slugs was particularly important for cereals last autumn, notes Bayers Carole Ferguson. "The effect is useful because it works underground to stop slugs feeding. But Secur is not a slug killer and we must ensure farmers do not think it is.

"It has little effect on leaf shredding, and alone should not be relied on to wholly protect cereals from slugs." In known problem areas Draza (methiocarb) is recommended as back-up, she says. &#42


&#8226 Kent field comparison.

&#8226 Remarkable surface effect.

&#8226 Less hollowing with imidacloprid.

&#8226 Not a slug killer, stresses maker.

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