Robust fungicide strategy vital to protect cereal yields

Article taken from the Farmers Guide

Almost every wheat and barley field under Craig Green’s care has been earmarked for a T0 spray.  Net blotch in barley and septoria in wheat are key targets, though patches of rhynchosporium, mildew and rusts lurk in many crops.

T0 programmes have been relatively robust, typically Torch (spiroxamine) plus Kayak (cyprodinil) in barley and chlorothalonil and Ceando (epoxiconazole + metrafenone) in wheat.

It’s not the cheapest of starts, Norfolk-based Agrovista agronomist Craig admits.  But there will be no letting up at later timings, he stresses.

“Once a crop is in the ground it needs looking after.  Even at current grain prices the extra yield achieved using a robust programme throughout the season easily outweighs the additional fungicide cost.  There’s no point treating a 10t crop like a 7t crop – yield is king and where possible we must do all we can to protect it.”

The T0 application will damp down diseases and prevent them gaining a strong foothold, he explains.  “However, with the later T1 and T2 timings we need to ramp up the programme to protect key yield-building leaves, and awns in the case of barley.”

Barley

Many crops are thick and lush, ideal for disease development, says Craig.  “The T1 timing is key in barley – it’s when grain sites are set so we are potentially protecting a lot of yield.”

He favours a half-rate of Jaunt (fluoxastobin + prothioconazole + trifloxystrobin) with a protectant such as Fielder (chlorothalonil + proquinazid) at half rate or less, where mildew is present, or Cebara (cyprodinil + isopyrazam) at around a quarter rate to maintain protection through to T2.

Actual rates will depend on the T0 strategy, says Craig.  If it was omitted there could be three week’s worth of disease build-up to contend with at T1, or if low rates of less effective products were used disease levels could be increasing fast.

The T2 barley spray is applied when awns are at the paintbrush stage as they are important contributors to grain fill.  A repeat dose of Jaunt plus Arizona (folpet) is favoured has the edge on abiotic spotting and rhynchosporium,” says Craig.

Wheat

Septoria remains the key target at T1.  A protectant such as Fielder or chlorothalonil is mandatory with rates tweaked according to disease presence.  “We need to protect against rain splash down the line and their multisite activity on pathogens helps prevent selection for resistance.”

Additional products will be influenced by a variety’s disease resistance scores.  “I’ll use Nebula (boscalid + expoxiconazole + pyraclostrobin) on robust varieties such as Evolution, and Variano (bixafen + fluxastrobin + prothioconazole) on varieties that are more susceptible to septoria, like Santiago.  I’ll recommend both at 1.25 litres/ha.”

Variano is almost as good against eyespot but may require extra help with rust, he notes.  “I’ll add a bit of Centaur (cyproconazole) if that’s the case.  “For that reason, Nebula is preferred in a complex tank-mix, as it applies several fungicides in one formulation.

Crops that missed a T0 will need a close eye, he advises.  “Be prepared to top up at T1.5 with some triazole if disease starts to break out.”

T2 will be a straightforward choice between robust rates of a Xemium-based product such as Librax (fluxapyroxad + metconazole) or Adexar (fluxapyroxad + epoxiconazole), plus chlorothalonil or Fielder to maintain multisite activity in the mix, or a bixafen-based product like Variano or Aviator (bixafen + prothioconazole), he advises.

“Both types do a very good job – they have good curative activity, important at this key timing.  Librax possibly has the edge, especially when bolstered with some Ennobe (epoxiconazole + prochloraz) – many customers remarked how well this combination persisted last season andhow green crops looked.”

Craig will recommend Velocity, an oil-based adjuvant, especially where air inclusion nozzles are used.  “It improves performance, allowing growers to get job done and improve timing without having to sacrifice efficacy and yield.”

Oats

Most oat crops won’t need a fungicide until T1, around mid April, says Craig.  “Galileo (picoxystrobin) is good starting point to control crown rust.

“T1 often follows on very quickly in oats, so be prepared.  Depending on disease level and T1 choice I’ll probably use Ceando/Galileo.  This approach delivers a good variation of actives and good activity against brown rust and mildew.”



“Craig Green is an agronomist with Agrovista, based at Great Ellingham, Norfolk (craig.green@agrovista.co.uk) 

 

10 April 2015

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