Autumn weather makes spring crop savings possible

15 February 2002




Autumn weather makes spring crop savings possible

No two years are the

same, but the contrast of

spring 2001 to this year

could hardly be greater

and that has big

implications for herbicides.

Andrew Swallow reports

OPEN autumn weather means herbicide savings will be possible in winter cereals this spring, says a leading Yorks-based agronomist.

"Weve had a kind autumn," says Paul Power of Phoenix Agronomy. "Crops were drilled in good condition and 85% have been sprayed with an ipu/dff or ipu/pendimethalin based autumn herbicide.

"The result is spring broad-leaved weeds will be few and in a smaller spectrum than last year. Mostly it will be the usual culprits that need targeting – cleavers and volunteer oilseed rape."

In crops needing an early pgr and perhaps a pre-T1 fungicide, that is a good opportunity to clean up cleavers with Boxer (florasulam) at 100ml/ha, a two-thirds rate, he suggests.

"You need a chemical that will work in the cold. Boxer surpasses Eagle, and if it is warm enough for the pgr then it is warm enough for the Boxer," he says.

A possibly cheaper and faster acting alternative is Platform S (carfentrazone-ethyl + mecoprop-P).

"Its very good on cleavers and volunteer oilseed rape and works well in the cold, but it is not as broad spectrum."

However, speed is not important early in the season and in contrast to Boxers slow but sure kill, larger cleavers can recover from a Platform treatment, he warns.

When daytime temperatures start hitting 10C (50F), without night frosts, Starane 2 (fluroxypyr) comes into the equation, but Mr Power warns against leaving cleavers control too late.

"Cleavers are very competitive and by GS 32/33 they can do a lot of damage, plus in a fast-growing crop coverage can become a problem. You might not get 100% control and end up having to go again," he warns.

When going early with herbicides and pgrs growers must keep one eye on the weather forecast. "You should not have a multiple product tank-mix going on before a frost."

Later sown crops, such as first wheat after roots, are still worth treating with ipu up to the end of February if grass weeds are expected. That may well be all that is needed for broad-leaved weeds too. "Take a look later and make a decision on what is there."

Without ipu a purely contact approach will be necessary, probably relying on sulfonylurea chemistry.

Growers should be wary of going too early with such products because late emerging creeping thistles, an increasing problem in many areas, and poppies may be missed, advises Mr Power. &#42

&#8226 Good autumn control.

&#8226 Cleavers and volunteer osr main targets.

&#8226 Early clean up preferable.

&#8226 Savings possible.

Mr Powers approach for wheat can largely be applied to winter barley. But take care with the more active pgrs due to the greater sensitivity of the crop, he warns.

Beware of leaving cleavers control until too late, warns Paul Power.


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