Whatever the weather this spring, growers can’t afford to let up on disease control, Paul Spackman discovers

Large amounts of inoculum in crops means that investing in a robust fungicide programme throughout this season is worthwhile, according to Velcourt.

“There’s a lot of septoria at the base of crops and yellow rust is already featuring in many areas,” says the firm’s technical director, Keith Norman. “Mildew has gone away recently, but there’s still a lot of inoculum about.

“Whichever way the weather goes, it looks like being a good year for diseases – a hot and dry spring/summer will favour rusts, wet weather will favour septoria and if it’s wet and dry, we could all diseases, including mildew.”

Many T0 sprays have been delayed by poor weather, but that is no reason not to go on with one if you haven’t already done so, he says. “As a company, we’ve always said the T0 is a valuable insurance policy, particularly if T1 sprays get delayed. A lot of the modern fungicides are excellent long-term protectants, which enables you to adopt a robust programme from the start, rather than ‘fire-fighting’ disease.”

Mr Norman says average fungicide spend across Velcourt farms ranges between £44 and 72/ha for a four-spray programme. “Typically, this will include a triazole-based T1 and T2, bringing in a strobilurin at T2 also.”

Trials at last year’s Cereals eventnear Royston in Hertfordshire found that applying a strob in mid-April suppressed rust for eight weeks. “That persistence was a real surprise, but plants need to be relatively clean before the strob is applied if you’re going to get the most protection out of them.”

Adrian Whitehead manages 2200ha of combinable crops for Velcourt near Sleaford in Lincolnshire. Some of his T0s were delayed, but he “pushed hard” to get them on last week, even though some early-September-drilled wheat was approaching the T1 timing. “A T0 builds insurance into the system. Last year, for example, we thought we could get away without using a T0 on Alchemy, but it broke down to rust.”

With about 1600ha of crops to spray each year, getting over the whole area with one sprayer can be a big challenge, he says. One 4000-litre SAM self-propelled sprayer, fitted with GPS auto boom shut-off and auto height control, does all the spraying and 75% of the fertiliser application.

To ensure the machine is kept working in the field for as long as possible a separate man is employed run a water bowser with a 2000-litre tank on the back to pre-mix chemicals. “When you’re running a £100k sprayer, you don’t want it wasting time acting as a taxi driving down the road to fill up,” Mr Whitehead says. “Having someone doing all the mixing means the sprayer operator can put in fairly big, stress-free hours. We probably average over 200ha a day.”

Across many Velcourt farms, including a T3 spray in the fungicide programme is fast becoming the norm and Mr Whitehead is no exception. “We’re in a high-risk mycotoxin area and most of our wheat goes for low-grade milling, so the T3 has a significant role to play. The milling premium we get easily pays for the cost of that extra spray.”

Velcourt at Cereals 2008

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The preventative and curative strengths of a range of products will be examined on Velcourt’s stand at the Cereals event (11-12 June). Industry standards Proline (prothioconazole) and Tracker (epoxiconazole + boscalid), alongside a number of others, including Fandango (fluoxastrobin + prothioconazole), Cherokee (cyproconazole, propiconazole and chlorothalonil), Firefly (prothioconazole + fluoxastrobin) and Opus (epoxiconazole), will be applied to plots of Cordiale at T1 (preventative) or T2 (curative) only.

“Most of the industry will be using either Proline or Tracker at T1, so it’ll be interesting to see how they compare against some of these other treatments,” Mr Norman says.

One of the T1 treatments will be 0.4 litres/ha Proline mixed with 0.67 litres/ha Poraz (prochloraz). “We know from a LINK triazole resistance project we are involved with that prochloraz gives useful suppression of one mutant septoria race, which has proved tougher to control. Using this co-formulation could take out these races and pave the way for the partner product against the easier-to-control I381V populations.”

Growers will also have their first chance to see the performance of Bayer CropScience’s new fungicide, codenamed BAYF869. The product represents a big step forward in broad-spectrum disease control and yield, the firm’s Gary Jobling says. “It’s in full-scale registration trials at the moment, but we’re hoping to bring it to the market for spring 2010.”