With the recent unsettled weather, sprayintervals and dose rates will need to be closely monitored heading toward theimpending flag leaf spray, warn technical experts from crop protectioncompanies BASF and Syngenta.
This advice comes as part of the TON partnership,a joint campaign launched by Syngenta and BASF in the UK, to raise awareness ofthe potential issues of fungicide resistance in cereal crops and providepractical guidance to growers and agronomists to help manage for it.
Louis Wells, agronomymanager with BASF in the north east of England, who helps to manage the BASFbiodiversity and trials site at Rawcliffe Bridge Farm in Goole, Yorkshire, isseeing Septoria tritici in the base of most wheat crops in early April, so withthe recent unsettled weather this is ripe to move up the crop he warns.
Whilst he is notseeing much yellow rust in early April he adds that there are still many rustsusceptible varieties in the ground such as Santiago and Kielder, so they willneed careful monitoring.
With this in mind andthe unsettled conditions forecast, managing the interval between the T1, growthstage 32 and T2, growth stage 39 sprays, when the flag leaf blade should all bevisible – will be critical. Timing is all about how long leaf 2 has been out if more than 10 days then the flag leaf spray has to go on even if not allthe flag leaves are out as it will be necessary to go on again as soon as theears are out.
However he is keen topoint out that dose rate of fungicides at T2 will be equally important to thinkabout. SDHI containing fungicides at T2 are essential and dont skimp on therate; consider the rate of the SDHI first as that will determine the rate ofcontrol. Triazole are also essential as components of the tank mix at T2 providingactivity against Septoria and rusts and aiding resistance management.
If weather conditionsmean that spraying is delayed, then dose rates should be kept up.
Jonathan Ball of BASFsuggests that where possible adding 1l/ha CTL where appropriate offers not onlya more robust treatment but as a means of resistance management which is a keymessage of the TON campaign.
Looking at barley,Syngenta field technical manager Iain Hamilton says there was plenty of diseaseinoculum in early spring, so it is important not to let this get out of hand.
Varieties also differin their disease susceptibilities, he says, for example with some winterbarleys being more susceptible to Rhynchosporium and others to brown rust. So aone size fits all approach to fungicide programmes shouldnt be relied on, headds.
As well as achievingeffective disease control, its also important to protect the fungicides wehave available in barley from a resistance management perspective, says MrHamilton.
Using strategies andspray timings to keep barley crops in a protectant situation is useful in thisregard because it gives you a wider range of fungicides to choose from bothprotectant and curative.
Whats also useful isthat mixing fungicides with different modes of action, such as SDHI + triazole+ partner, not only aids resistance management, but has also been shown toincrease barley yield over a two-way tank mix. So there can be income benefitsfrom using multiple modes of action as well.
Key messages from the TON launch for protecting fungicide performanceon-farm for both wheat and barley:
A robust programme early in the season is important to avoid chasing disease
Multiple modes of action at each timing help to mitigate the effect or delaythe onset of resistance.
Always aim to apply fungicides preventively to get the best levels of control.
Triazoles are important to protect SDHIs, but SDHIs also protect triazoles.
Multi-site fungicides are important to protect triazoles as well as SDHIs.
Driving for yield is the way to ensure good margins, even with low commodityprices; in wheat the long term average fungicide response > 2t/ha(+250/ha).
Dont let resistanceaffect profits
According toagricultural economist Graham Redman of The Andersons Centre, if resistancereduces the effectiveness of inputs, it could have a substantial impact on theeconomic performance of cereal crops.
He added that fungicidesstill provide a significant return on investment, so it is vital that growersand their agronomists sit down together and take into account the agronomic andfinancial impact of the fungicides programmes planned for the spring.
Pointing to farm modellingfor feed wheat for 2015, he says that a drop in wheat yield, for example due tofungicide resistance, would push up the cost of production per tonne.Alternatively, he says resistance could result in having to spend more just tomaintain the same output.
New approaches willbe needed if resistance to fungicides increases, points out Mr Redman. Sowhile weve got good fungicides, lets look after them so they work for yearsto come. Output has to be maintained.
BASF and Syngenta willshortly be launching the TON partnership website. The site will containinformation from leading technical experts from within BASF and Syngenta aswell as independent view on all aspects of cereal fungicide resistance. Formore information be sure to visit www.tonpartnership.com