10 April 1998

Sprays

– juggling for top response

New cereal fungicides will

figure in many spray

programmes this season.

But even where they are

readily available, low cereal

prices dictate caution, as

Andrew Blake found when

he visited our eastern

barometer

EVEN if he could obtain strobilurin fungicide, David Pettitt would not be using it this season.

His little and often spraying regime at West Hall Farm, Rickinghall, is already under way with low rate conventional chemistry backing his first growth regulator.

"Last year our triazole-based programme cost £55/ha (£22/acre), and I imagine that this year it should be down to £44/ha (£18/acre)," says Mr Pettitt.

A strobilurin-based approach, which would almost certainly involve adding a triazole for disease knockdown and to boost mildew control, could run to £105/ha (£42/acre), he estimates.

"With wheat at £70/t I would need an extra 0.85t/ha (0.35t/acre) just to break even."

With Zenecas own advertisements for Amistar (azoxystrobin) noting 1997 yield increases ranging from minus 2.8% to plus 28%, Mr Pettitt is wary of taking the gamble.

"To be fair most of the increases were in the 9-10% range," he says. "But if I am spending £60/ha (£24/acre) more than I did last year I want to be fairly sure of getting something back."

The same argument applies to lodging control, suggests independent crop consultant Simon Draper who advises Mr Pettitt on agrochemicals.

Growth regulators are key inputs. Even with a full programme of early and late applications, last years Fanfare barley was 85% lodged, notes Mr Pettitt. But relatively cheap chlormequat rather than products like Moddus (trinexapac-ethyl) and Meteor (chlormequat + choline chloride + imazaquin), remains the basis of this years defence against flat crops.

"With the current wheat price of £68 we have got to look very hard at what we use," says Mr Draper. "We know the newer materials are very good. But we have got to be very careful."

For maximum lodging control the chlormequat treatment, this year as Atlas, is always split two-thirds/one-third if possible.

At one stage sugar beet drilling, which took priority, looked as though it might force the latter approach. But with most fields still only at GS31 (first node) last week, Mr Pettitt reckoned he could still usefully adopt twin-spray tactics.

The lower dose is used second as the chemical is usually used more efficiently then because the crop tends to be growing faster, explains Mr Draper.

Septoria and traces of mildew in the wheats and brown rust in barley, all Regina this year, were the main disease targets for the first application. Only occasionally does eyespot merit a specific fungicide, says Mr Pettitt.

In the absence of a strobilurin, this years fungicide mixes are expected to be much as last years with Opus (epoxiconazole) forming the backbone because of its strength against septoria, explains Mr Draper.

Depending on disease pressure, Mr Pettitt is fully prepared to make five passes a season if necessary using low rates. The Amazone 18m mounted sprayer, with a total of 2000 litres (440gal) on board, can cover all the cereals in two 10-hour days, he notes.

Under the circumstances this spraying approach is the most cost-effective, adds Mr Draper. "We are not looking for a big window of opportunity." Application rates can easily be increased to offset slight delays, he explains.

First hit, the same for the wheat and barley, including 2 litres/ha of Atlas, was a mix of 0.25 of Mantle (fenpropimorph + propiconazole) with 0.2 of Opus, reducing to 0.1 on the more disease resistant Hussar. The plan is to be back on again in 10-14 days.

Main problem field is 6.5ha (16 acres) of low seed rate Sep 8-drilled Consort after rape. It suffered patchy germination and still has far too many tillers on some plants.

The patchy growth habit makes application timings especially tricky, notes Mr Draper. "Luckily it is only one field."

Cash in hand…new fungicides promise much, but could conventional chemistry produce more profit, asks eastern barometer, David Pettitt?