22 March 2002

Vital to keep on top of lodging

and disease, delegates are told

Managing this years thick,

forward cereal crops

was a key issue at the

recent series of

FARMERS WEEKLY/BASF

Brave New World of Arable

Farming meetings at

Perth, York, Coventry,

Newmarket and Winchester.

Charles Abel reports

GROWERS wanting to preserve the potential of their well-established, early-sown wheats need to pay extra attention to lodging and disease control this spring.

Although seed rates were cut in many cases, they were still not low enough to avoid significant lodging and disease pressure this spring, says Graham Hartwell, Yorks-based technical manager with seminar sponsor BASF.

As a supplier of plant growth regulator and fungicide products that could be dismissed as sales patter. But Mr Hartwell and colleagues from around the country have good reasons to support their claims, which are widely backed by trade and independent agronomists alike.

Key to the problem is good establishment and good winter conditions, leaving growers with management problems as well as huge crop potential this spring.

"In many cases growers have not really grasped the nettle on seed rates and have not cut back far enough," says Mr Hartwell. The mild winter has led to a lot of over-thick crops, which are likely to produce thin, spindly tillers, making them particularly prone to stem lodging.

Competition between root systems also risks root lodging, when the entire root plate pulls out of the ground. Thick crop canopies also harbour more disease.

Colleague Andrew Speed, from Lincs, agrees. "The potential of crops is very good. But we do stand a pretty good chance of seeing some crops lodge this year, despite everyones best efforts."

So what should growers do? The consensus is that many will need to become experts in tiller killing and input timing.

"Start planning now, look at the whole season and pay particular attention to input timings," advises Mr Hartwell. The main goal for most wheat growers this spring is to "keep it up and keep it clean".

Delay first nitrogen until at least late March, when tillering is likely to end, he says. "Most crops can afford to lose some tillers. Only if shoot numbers drop below the HGCA guideline of 1000-1200/sq m should 40kg N/ha be applied and even that should not go on before late March.

"At the moment, nitrogen is going to make you more money sitting in the barn than it will in the field."

In many cases yellowing is due to manganese not nitrogen deficiency, adds south of England colleague Clare Tucker.

The exceptions will be later drilled crops and those suffering from pest damage. The incidence of gout fly, wheat bulb fly and frit fly damage are all increasing, probably a legacy of the very mild, open autumn, says Mr Speed. "If youve lost tillers treat the crop as a lower population, even if the surviving tillers are well grown."

An appropriate early pgr should be used to strengthen and shorten stem bases in over-thick crops, probably split for best effect, says Mr Hartwell.

But applications must wait until tillering has stopped. "Apply pgr too early and youll just stimulate more tillering. Timing will be crucial, get it wrong and it could be a potential waste of money."

Indeed, judging growth stages is set to be a big issue. "Ive seen crops of Claire 10-12in tall which are still at GS30, and 3-4in tall Malacca that is closer to GS31. Dont be conned by crop size. Its going to be vital to use stem dissection to actually check the crop to get input timings right. Timing is the watchword."

Ms Tucker agrees. "Getting pgrs on after tillering has stopped, but before the crop starts moving, will be critical. You cant use them to shorten internodes once they have extended. But if you get the nitrogen right and use an appropriate rate of pgr now you should be able to even out tiller numbers, reduce crop height and strengthen stem bases, so there is less need for pgrs later."

The story is similar for disease control. Forward crops with good yield potential could merit a pre-T1 reduced rate of triazole, with or without some morpholine, to clean-up existing disease pressure, says Mr Hartwell.

"In severely infected situations it can pay to include the fungicide with the first pgr spray."

But whether or not a T0 spray is used, achieving continuous protection throughout the rest of the season will be the challenge this year, he advises.

"We just dont know how long the gap will be between T1 and T2. It could be three weeks, it could be seven. Using a T0 spray now can help by providing a clean canopy for the T1 spray, so improving the effectiveness of later products."

If timings get stretched, due to difficult weather windows, for example, growers will need to look to use more robust strobilurin products at T1 and T2, he advises.

"Using a product at T1 with more curative activity will make particular sense if you have been unable to get on with a T0 fungicide, helping to recover any ground lost in the battle to keep infection at bay," adds northern colleague Simon Townsend.

"With the new chemistry now available growers have a much better chance of successfully bridging the gap between the T1 and T2 timing, with real curative activity to clean up any established infection and good protection to keep the crop clean going forward," says Mr Speed. &#42

PRODUCTIONISSUES

&#8226 Well-established, thick crops.

&#8226 Seed rates still too high.

&#8226 High lodging + disease risk.

&#8226 Timings critical to success.

&#8226 Exploit new chemistry.