10 May 2002

T2 spraying spotlight for flag leaf

After Aprils long dry spell,

the sudden soaking of

winter wheats is bringing

T2 spray programmes into

sharper focus on farmers

weeklys barometer farms.

Andrew Blake reports

THE threat of renewed disease pressure, especially in the south-west and to crops made extra lush by otherwise welcome rain at the start of the month, has become a key driver around the regions.

After some temptation to trim T1 inputs, most of our regional representatives are planning a fairly robust fungicide regime at the critical T2 flag leaf timing. Indeed some extra unscheduled late pgrs may be required.

"We just cant afford to take our eye off the ball with septoria," says Somersets Chris Salisbury. "In the past I have seen plants completely killed in sprayer misses."

"After all the rain canopies will really start to move and disease pressure is bound to increase," says Warks-based William Hemus. "But we will spend only what is needed for optimum gross margin. Just because we used a bit less at T1 does not mean we need spend more at T2."

South-west and western estimates suggest typical combined T1 & T2 outlay will be about £59/ha (£24/acre).

Mr Salisbury is keen to compare results from the different T2 approaches of his agronomists, Velcourts Jon Midwood advising on light land near Yeovil, and Agrovistas Mike Rastall, who oversees programmes on his heavier soils near Taunton.

Both echo his views on the Septoria tritici threat. "Our trials show the pressure down here is incredible and we cant afford to ignore it," says Mr Rastall.

Tactics at Yeovil, where slight dry weather savings were made at T1, will be based on 1 litre/ha of Twist (trifloxystrobin) with epoxiconazole at a dose related to disease pressure at spraying. "We will use 0.2-0.3 litres/ha if it is low, but 0.4-05 if it stays high," says Mr Salisbury.

"We are very happy with results from Twist/Opus," says Mr Midwood. "I would not rule out Opera – it looks very good on one years data. But the price gap is too great with wheat under £60/t."

At Taunton Agrovistas trials suggest Opponent (pyraclostrobin + kresoxim-methyl + epoxiconazole) with its kick-back action, probably at 0.65-0.75litres/ha, is best option on Consort, Equinox and most of the Savannah, says Mr Rastall.

But some Savannah after spring barley hit by take-all will not justify that expense unless rain revives its potential. "We will assess it nearer the time, but it will probably get just a straight triazole." &#42

With flag leaf emergence nearly upon them, Chris Salisbury (left) andJon Midwood are keen to keep septoria at bay to maximise photosynthesis for the developing ear (inset).

&#8226 Protection from septoria main aim.

&#8226 Strobs key feature for most crops.

&#8226 Costs big concern with wheat at under £60/t.

&#8226 Lodging fears from rapid N uptake.

Late growth regs

Luxury nitrogen uptake will make it even easier to defend applying Terpal (2-chloroethylphosphonic acid + mepiquat chloride) pgr used routinely on potentially high yielding crops, says Mr Salisbury.

"They are bright blue, though thankfully not over-lush because of reduced drilling rates. We do not have a canopy of big floppy leaves. But we shall still use Terpal, especially at Yeovil where the ground tends to bulldoze when we combine flat crops."

The surge in N uptake by Sandy Walkers wheats in Shropshire means late season pgrs will need reviewing, notes Agrovista agronomist Neil Buchanan. "It could also encourage mildew, which will need watching, but the kresoxim in Opponent should give a reasonable level of control."

On Peter Wombwells Essex farm agronomist Paul Johnson is wary of late pgrs. "Lodging is a concern, but I do not like using Terpal unless I really have to. It can be harsh on crops and on some of Peters sandier land they can burn up."

&#8226 Midlands

Having used kresoxim-methyl products at T1 in Warks, Mr Hemus plans a switch to Twist with a triazole, or perhaps Opera (pyraclostrobin + epoxiconazole), for his T2s mainly for their greater potential return, but also to ease resistance pressure.

"We have used Landmark and Mantra for two years and I am uneasy about continuing with them. The trickiest thing will be deciding doses. We will use between two-thirds and full depending on how long we need protection. We never go below two-thirds."

&#8226 South

In Surrey Giles and Simon Porter had two plans for their T1s completed only a fortnight ago. The first was to trim rates had it stayed dry.

"But we went for plan two because rain was forecast," says Giles. "It looks as though it has worked well. On Malacca and Tanker we used 0.5 litres/ha of Twist with 0.3 of Opus." Isengrain and Claire received a Flamenco (fluquinconazole) base treatment with chlorothalonil and quinoxyfen added, respectively.

"That should give us more than enough protection to get to T2 when we will use mainly strobs."

&#8226 East

Work showing trifloxystrobin dilutes grain protein less than other strobilurins has encouraged Farmacys Paul Johnson to choose it as the main T2 component for Peter Wombwells Essex milling wheats. "It is also good value for money and you can add what you like. Opera would be fine in happier times."

&#8226 West

So far so good is Masstocks Peter Jones view of Sandy Walkers August-sown Claire in Shropshire. Caramba (metconazole) planned to accompany 0.5 litres/ha of Tucana (pyraclostrobin) to boost fusarium control, will help keep mildew at bay, he says. "If it really starts to come in we will add a bit of morpholine to knock it out."

&#8226 Scotland and NI

In Angus T2 wheat treatments are still a long way off, notes Robert Ramsay. "We have had less rain than down south and I am feeling fairly safe. We have not had many rain splash events."

Whole-crop silage wheat in Londonderry may not merit as robust a T2 as it would for combining, so a strobilurin will probably be absent, says Robert Craig. "But we still need to keep it clean."

Regional revamps