31 May 2002

Ear care boosts yields

Our latest baseline advice

article explains why it will

be important to protect

cereal yield and quality

with an appropriate ear

emergence spray this year

MOST wheat crops will benefit from a T3 or ear spray this year, believes Andrew Blazey of Norfolk-based Morley Agricultural Consultants.

Morley trials show the T3 spray pays for itself three years out of every four. "Last year was year four and there was no significant response. But a normal year brings a yield boost of 0.4-0.6t/ha," he says.

In extreme years the response can be as much as 1t/ha. "And this year looks like being a fungicide responsive year. Dry conditions earlier on have encouraged root growth, so it will be important to lengthen grain fill as much as possible."

But there are situations where a T3 spray is not necessary, he acknowledges. "Where there is a big area down to septoria resistant varieties and sprayer workload is tight, a better plan might have been to have used a strobilurin at T1 and a late T2.

"Also, farms in dry areas and on light soils, where drought conditions develop, are another exception."

The third scenario is with late-drilled wheat crops, which go through the spring and summer growth stages very quickly. "A two spray programme is perfectly adequate in this situation," states Mr Blazey.

Objectives

The aim of the T3 spray is to improve yield and grain quality, mainly by topping up the flag leaf spray, explains Mr Blazey.

"Its so important to get a marketing advantage when grain prices are so low, that it is worth spraying both feed and milling wheats," he continues. "Growers will improve grain specific weight. Achieving a bold sample is essential."

The main ear diseases are the fusarium species and sooty moulds. "Controlling sooty mould is cosmetic, the main aim of the T3 spray is to keep on top of septoria and prevent brown rust getting a hold."

Crops have been fairly clean this year, he reports. "Brown rust will be a threat on Consort type varieties if we get plenty of warm, dry weather. It was around earlier in the season."

Good fusarium control is very difficult to achieve as the spray timing is so critical, believes Mr Blazey. "There is a fear about mycotoxins in grain, but the issue isnt that simple. With a large area to spray, timing is so tight that it is impossible to be sure of good control."

Timing

The T3 spray should be applied at full ear emergence just before flowering, advises Mr Blazey.

"That is usually 10 days to two weeks after the flag leaf spray," he points out. "But be aware that many flag leaf sprays went on 5-7 days ahead of normal this year. So they might run out of steam a bit earlier."

A common mistake is to spray too late. "The timing comes so soon after the flag leaf spray, that its easy to miss. Thats an error, especially where the flag leaf spray was early."

Product choice

Amistar (azoxystrobin) with or without a triazole is Morley Agricultural Consultants preferred strategy at T3, as it offers good control of ear and foliar diseases.

Of the triazoles, Folicur (tebuconazole) is good and will need to be used at three quarters rate if fusarium control is the priority.

"If you are going after fusarium, then spray 2-3 days before flowering. You must be certain of your ability to meet the timing and use a robust rate."

Metconazole (as in Caramba) is also effective. "There is a case for using Amistar alone on cleaner varieties, where flag leaf sprays were delayed or the disease risk is felt to be low. It should give a clean, bold sample."

Costs

Be prepared to spend 15-20% of your total fungicide budget on the T3 spray, he recommends.

"There will be a temptation to omit the last spray," he says. "But marketability is so important now, that it is not worth risking shrivelled grain and low bushel weights."

Rates can be cut in many circumstances, although the final decision should be taken nearer the time. "Between 0.3-0.5 litres/ha of Amistar and 0.25-0.5 litres/ha of Folicur should do. The exception is where you need 0.75 litres/ha of Folicur for fusarium control."

He believes mycotoxins are a complex issue, but wants to see more evidence before being convinced of the threat. "Growers may find it just isnt economic to control fusarium and completely eliminate mycotoxins." &#42

New standard in fusarium control

New Bayer fungicide JAU (prothioconazole) offers a new standard in fusarium control, outperforming all existing products, says Hungary-based fusarium expert Akos Mesterhazy. Microdochium is also controlled and when used in a co-formulation with Bayers new strobilurin HAC (fluoxastrobin) it offers the prospect of combined eyespot and foliar disease control at T1, says the firms Astrid Mauler-Machnik. Test marketing in the UK is expected next year.

T3 SPRAY

1 Economics T3 pays for itself three years out of four.

2 Response Typically 0.4-0.6t/ha, but can be as much as 1t/ha or none at all.

3 Exceptions Late-drilled wheats, crops on drought-prone soils and resistant varieties can be left without a T3 spray.

4 Aim Ear diseases (sooty moulds and fusarium) and top up foliar disease control.

5 Brown rust Will be a problem with warm, dry weather.

6 Timing Spray at full ear emergence, just before flowering.

7 Fusarium Timing is critical, spray 2-3 days before flowering with 0.75 litres/ha Folicur.

8 Products Amistar with or without Folicur or Caramba.

9 Rates Use 0.3-0.5 litres/ha Amistar with/without one quarter to one half rate triazole.

10 Costs Spend 15-20% of fungicide budget at T3 to safeguard marketability.