Beet seed treatment choice sets potential for 2011

Seed treatment choice on beet offer returns will determine the duration of 2011 crops’ exposure to virus yellows risk; this will impact on yield and profit potential.

The last two seasons of late aphid flight, caused by unusually cold winters, have been exceptions to the longer-term trend of warmer winters and earlier aphid flight. Broom’s Barn’s Dr Mark Stevens says that in more normal years we should expect to be seeing aphids in beet crops by mid May.

"Seven of the last ten years would have been virus yellows epidemic years if insecticidal seed treatments had not been used," he warns. BBRO trials have shown that yield losses from May infection are typically 25% and from July infection 5% to 8% can still be lost."

He therefore recommends all 2011 crops be drilled with the protection of a second-generation neonicotinoid seed treatment to set them up for full yield and profit potential.

British Sugar’s 2011 seed price list states that Poncho Beta and Cruiser Force will persist for up to 14 weeks after sowing; imidacloprid will persist up to 10 weeks from sowing and may slow emergence of beet by one to three days.

Dr Stevens rates this difference as critical. "With imidacloprid there has always been a risk of late virus infection whereas the two newer treatments keep crops protected through to the point of mature plant resistance."

He adds that despite the lateness of aphids in 2009, come September there was a lot of virus yellows visible in the Docking disorder area of North Norfolk where growers had not used any insecticidal seed treatment.

Bayer’s Dr Bill Lankford says historically growers there used Temik for free-living nematode control. "This also provided up to six weeks protection against aphids, so imidacloprid seed treatment was rarely used.

"Today’s carbamate granules only control aphids up to the first true leaves stage leaving beet potentially exposed for up to eight weeks, and as there are no longer any effective foliar sprays this makes virus yellows infection very likely in a high virus year."

Growers can eliminate this risk by drilling Poncho Beta protected seed he says. "It will see crops safely through to mature plant resistance and its broad spectrum control of soil pests and foliar pests will optimise establishment."

Independent agronomist Dr Pat Turnbull, who advises on beet crops in North and West Norfolk, including 1,500ha of light soils prone to Docking disorder, says these benefits have been borne out in her experience, mainly with using Poncho Beta.

"The new generation seed treatments give superb virus yellows control, help establish uniform plant stands and control capsids and thrips which used to cause a lot of damage.

"Over the last few years we’ve gained real confidence in using them in conjunction with Vydate granules. They don’t slow emergence, as we used to find with imidacloprid, and are certainly contributing to the higher yields now being achieved," Dr Turnbull concludes.

Dr Lankford adds that independent trials by Broom’s Barn have shown the difference seed treatment choice can make to crop potential for yield and profit. "Poncho Beta stands out as the leading insecticidal seed treatment consistently delivering 2.5 t/ha more than imidacloprid, and a tonne more than Cruiser Force."