29 October 1999

Early drilled wheats are coming under pressure

By Charles Abel

VERY-EARLY sown wheat plots on the Cereals 2000 site at Nocton, near Lincoln, look set to provide a real challenge for modern management and chemistry over the coming season.

Leaf and tiller production in the Madrigal winter wheat sown on Aug 27 on the low land brash site after peas has been prolific. Mild weather in late September/ early October has not helped.

"It just doesnt look right," admits Keith Norman, technical director for management company Velcourt. "We drill just as early on higher altitude sites in Yorks, Leics and the Cotswolds, but they dont look anything like this."

The plots are already as thick as would be expected in March, making winter kill a big concern. Excess tillers are also a worry. At the lowest seed rate of 140/sq m some plants already have eight tillers. That means over 1100 tillers a sq m, against a target of 600.

According to PBIC wheat expert John Howie up to 10 tillers a plant can be expected, taking the potential count to 1400/sq m. "We are going to have to adopt a very strict nitrogen starvation regime in the spring," notes Mr Norman.

"That is exactly the opposite of what we would usually do on a brash site, where we would normally go little and often and early to stimulate rooting. Here we are creating good roots in the autumn.

"The aim here is to see just how close to a theoretical maximum yield of 15t/ha we can get by getting the crop off to a flying start in the autumn. I think the latest management inputs should allow us to get to 12t/ha on this brashy site."

Mr Howie agrees. "We have other crops which look just as proud. Given the right management it will be all right. Unlike Charger, Madrigal does lose tillers relatively easily. The key will be to hold back on early spring nitrogen and pgr."

Although a seed rate of 100/sq m had been planned, 140 was chosen because of seed-bed conditions and slug pressure. A conventional rate of 240 seeds a sq m was also used for comparison. It looks ready to silage.

Rapid autumn growth was always anticipated. "We know Madrigal starts fast, slows in the winter and then develops moderately slowly in the spring," Mr Norman says. "It is not enough to look at a varietys autumn growth and make a judgement on its development throughout the season. Varieties show three distinct phases of speed of development – autumn-Dec, Dec-Apr and Apr-July."

Madrigals good standing power and good resistance to brown rust and mildew, rated 9 and 6, respectively, also suit it to early drilling, Mr Howie notes.

An autumn dose of Cycocel (chlormequat + choline chloride) is planned to boost rooting. Timing should avoid any boost to tiller survival. A mix of autumn trace element is also planned, plus sulphur in early spring.

Protection monitored

A combination of three new seed treatments has been used on the August-drilled wheat. Over the coming months protection from AgrEvos yet-to-be-approved seed treatment fungicide fluquinconazole will be monitored, as well as from Evict (tefluthrin) and Secur (bitertanol + fuberidazole + imidacloprid) for wheat bulb fly and BYDV control respectively. Two doses of Draza (methiocarb) kept slugs at bay.

Low and conventional seed rates of Charger sown in a simulated post-roots drilling slot in late October/early November will provide a further contrast, with both conventional and new technology input regimes.

Total spending on the early drilled crop may be higher. But Mr Norman is confident the extra yield will more cover the extra cost. There are other pluses too, such as workload benefits from the spread of crop development in autumn, spring and at harvest, he adds.

If the seed rate had been lower still the result may have been possible with less management input, he acknowledges. "But as it is it will be a good test for the new technology." &#42

Trials to study effect of seed rate on Secur

In a bid to unravel the true effect of seed rate on the efficacy of new anti-BYDV cereal seed treatment Sibutol Secur, Velcourt has established low rate sowing trials with manufacturer Bayer in Dorset. "We have gone down to 100 seeds a sq m with a Sept 1 drilling, which was equivalent to 80-85kg/ha, well below the companys advised 120kg/ha or 200 seeds a sq m," says Mr Norman. Effects will be monitored closely. In the meantime Velcourt has gone no lower than 200 seeds sq m in commercial crops this year until further information is available on seed rate reductions and the need for follow-up cypermethrin applications.