Deter-mined under pressure

Extreme aphid pressure nationally gave Deter a run for its money last autumn and winter. Hopes that it would stand alone were dashed, but there was good BYDV control where used with a follow-up pyrethroid spray.

Mild conditions allowed aphids to fly throughout winter for the first time, leaving untreated plots in BYDV trials riddled with infection, says ADAS’s Jon Oakley.

“I’ve never seen a year like it. September-drilled crops definitely needed a two-hit aphid control strategy. Using Deter would have taken the worry out of getting an early spray on at least.”

Bryce Rham of Procrop in Shropshire feels the seed treatment gave a little over eight weeks’ protection against aphids, and achieved total BYDV control where it was followed up with cypermethrin in November. Where the top-up was delayed until March, some symptoms are showing, but not as many as where Secur was used, or cypermethrin applied in late October with a herbicide.

Mr Rham recommends Deter for wheat drilled in the first two weeks of September, when aphids are most active.

For later drillings, too, there could be a case for the seed treatment, says TAG’s Richard Overthrow. “Our trials between 2003 and 2005 suggest wheat drilled at the end of September doesn’t usually require more than one well-timed pyrethroid spray. However, ask yourself whether you are prepared to spray to a deadline if there’s no other reason to be going through the crop.”

With application costs of £7-10/ha on top of the product cost of £2.50/ha, Deter may look attractive, particularly when you are stretched for manpower, he says.

active ingredients

  • Deter – clothianidin- Secur – imidacloprid
  • Redigo Deter -prothioconazole + clothianidin
  •  Crystal – flufenacet + pendimethalin
  • Atlantis – iodosulfuron + mesosulfuron

Steve Cook of Hampshire Arable Systems sees Deter as the answer on heavier soils where Crystal is used for blackgrass control. He is sure it pays for itself, even with a follow-up. It cost very little extra to put cypermethrin into the tank with Atlantis last November, he notes. Some of his growers would rather not use a pyrethroid in October because beneficial insects and game birds are still present.

If you are deciding on the basis of cost, you should take account of damage by other pests that Deter claims to reduce, suggests Mr Oakley. Although neither ADAS nor TAG has any trials data to support the label claim that slug hollowing is reduced, the general consensus is that it does.

Frontier Agriculture‘s trials show an 8% increase in plant population at GS10 using Redigo Deter rather than a single-purpose treatment, and ear counts taken last month suggest that will be reflected in yield. The company’s Charlie Whitmarsh says the contribution of slug control is considerable.

“If you add into the equation the cost of not needing slug pellets, the case for Deter strengthens further. And don’t forget the energy saving from reducing passes. I shall certainly recommend it where wheat follows oilseed rape on heavy land.”

Someone who can’t get excited about Deter is Richard Cartwright of Chichester Crop Consultancy, who had expected better gout fly control. “Gout fly came in over a long period and some early-drilled crops lost plants with four tillers, despite the Deter treatment,” he says. “I don’t think it is any better than Secur as was being claimed. It really isn’t an option to omit a pyrethroid spray once eggs have been laid.”

Mr Cartwright also disputes that Deter is two weeks more persistent against aphids than Secur. He recommends growers stay with Secur and follow up with one or two pyrethroid sprays when applying other products.

Deter seed treatment could buy growers valuable time during busy periods.

Deter could be well worthwhile this autumn despite a difficult last winter, says ADAS’s Jon Oakley.

Case Study

  • Peter Knight expects to see odd plants infected, but this summer the 200ha of wheat on his 500ha arable farm near Guildford, Surrey, is free from BYDV. And crops under the min-till system suffered no slug damage. He believes Deter and a November-applied pyrethroid are to thank.

    “In the past we’ve used Secur for aphid control, but always needed slug pellets in our mid-September-drilled wheat after rape,” he says. “This year, we used Deter across the lot and didn’t catch enough slugs to justify pellets. We’ll continue to use it for these heavy land situations.”

    Mr Knight finished up his supplies of Secur on the remaining wheat, mostly later sown on lighter soils. He hasn’t decided whether to substitute Deter here. It will depend on planned drilling dates and herbicide policy.

    “It feels good to be using a product which has less environmental impact, and allows me to do less spraying and use less slug pellets,” he says. “But where I’m sowing in October and going in anyway with a post-emergence herbicide, I shall stick with a pyrethroid.”

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