A recent Farmers Weekly survey, in conjunction with BASF and Syngenta, revealed growers might be underestimating fungicide resistance and prompted a gathering of experts to highlight concerns and provide practical advice on how to combat the problem.
Losing effective disease control from cereal fungicides will erode farm profits and growers must learn how and when to best use available products to reduce risk of fungicide resistance development.
Over the last 16 years, HGCA Recommended List trials have shown an average response to fungicides of 2.2t/ha and in 2014, the figure was a massive 4.2t/ha.
This proves there is still an effective portfolio of disease controlling products and farmers themselves are in control of whether they remain so by how they are applying them in the field.
In the maritime climate of the UK, potential problems with fungicide resistance are more acute as disease pressure is high and fungicide use is intense compared with many other grain producing nations.
As fungicides still provide a significant return on investment, growers must listen to best advice on counteracting resistance according to Graeme Redman, partner at business consultant Andersons.
He referred to research carried out by BASF that highlights the potential impact of losing SDHI fungicides as a component of disease control programmes.
In the eight trials, untreated plots were compared with an SDHI/azole and a high-dose azole only programme. The programme including SDHIs gave a 2.6t/ha yield response and the high dose azole programme gave a boost of 2.1t/ha.
But more telling was the return on investment.
The higher cost of the high dose azole programme in achieving half a tonne less grain gave a return of £61/ha, compared with £167/ha from the more effective and cheaper SDHI/azole combination.
“Half a tonne may not seem very much, but on many farms that could be the difference between a profit or a loss, particularly when prices are depressed,” says Mr Redman.
In a recent Farmers Weekly survey, published on 5 December, 55% of the grower respondents believed SDHI fungicides were at risk from fungicide resistance, but they are classed as “moderate to high risk”.
With the higher risk and the potential, growers can achieve a 63% higher return than a high-dose azole fungicide programme, which highlights the importance of ensuring they are used correctly.
Mr Redman urged growers to use their agronomists, who on average spend one in five working days learning the latest agronomic research, to ensure they are implementing the correct strategy.
“Have the conversation and understand the financial, but also the agronomic impact of fungicide programmes ahead of the spring,” he added.
Best practice advice
Fiona Burnett, crop protection team leader at Scotland’s Rural College (SRUC) and chairman of the fungicide resistance action group (FRAG), said there has been mixed messages surrounding fungicide resistance due to the complex science involved, which is open to different interpretations.
“With those mixed messages it’s been hard for people to take ownership of the issue and act upon it themselves, but getting together and coming to a common consensus will be crucial.
“It’s about getting a balance between effective control in the short term and achieving long-term sustainable use with the correct stewardship,” said Dr Burnett.
So how can growers achieve that balance?
BASF’s Ben Freer believes the key to achieving good control of diseases in winter wheat is placing more importance on the earlier timings at growth stage 30/31 (T0) and 32 (T1).
The decline in efficacy of the key azoles prothioconazole and epoxiconazole as curative fungicides against septoria means that growers should be treating preventatively.
Those key azole actives – along with SDHIs and multisite active ingredients such as chlorothalonil – are effective at keeping disease out.
Therefore, robust early applications at the correct timings will prevent septoria getting a foothold and negate the need for extra sprays that increase the risk of fungicide resistance developing.
“Once you let disease in, you’re in a curative situation and already losing yield. No product can eradicate septoria, so if you start weak, you aren’t going to claw back what you have lost,” said Mr Freer.
He also urged growers to use mixed modes of action throughout the programme at all timings to ensure all are supported, with three way SDHI, azole and chlorothalonil mixtures at the key T1 and T2 timings.
While all the focus tends to be on reducing the resistance risk in key wheat disease septoria, barley diseases are also showing reduced sensitivity to some fungicides.
Azoles have shown a slight decline in efficacy against both rhynchosporium and net blotch, with SDHIs and strobilurins remaining effective against rhynchosporium.
However, SDHI and strobilurin resistant isolates of net blotch have been found, so there has been a loud warning shot fired to barley growers about the potential loss of disease control products.
Syngenta’s field technical manager Iain Hamilton echoes Mr Freer’s sentiments that prevention is better than cure and “stacking” modes of action to control disease will be vital in barley crops.
“The only way you will completely prevent fungicide resistance is to stop applying fungicides altogether, but we know that isn’t practical.
“In barley, concentrate on protecting the lower leaves and use all the chemistry available in the right place,” he added.
Integrated strategies for disease control will also play a key role and Dr Burnett said genetic resistance to disease such as septoria in wheat could take the pressure off fungicide programmes.
“There is a difference between a 5 and 6 on the Recommended List and it can buy you some time when fighting against the practicalities of getting spray timings correct,” she added.
Farmer’s take on resistance
Christopher Day, Lincolnshire
“The concern is that we end up with a problem and no solution. If there is anything to take from today it is that we must using these products responsibly. A key strategy is using more resistant varieties to take the pressure off the chemistry, people just aren’t dazzled by dirty varieties anymore.”
Henry Ward, Lincolnshire
“We don’t want to make a rod for our own back and you’d be pretty narrow minded to use cheap and cheerful programmes with a narrow group of actives. We are seeing the decline in azoles on our farm and are using more robust programmes with multisite chemistry through all the timings.”
Steve Bumstead, Bedfordshire
“We all need to be singing from the same sheet when it comes to fungicide resistance and it needs to start with the manufacturers and distributors and agronomists need to highlight the importance of this to growers. We all need to respond to keep what’s in the tool kit.”
Growers’ pain in the azole
As well as fungicide resistance threatening effective disease control, a European Commission definition of endocrine-disrupting chemicals could result in key azole fungicides being banned.
If this is realised, it will not only mean a dip in crop yields and farm profit, but it will also exacerbate the fungicide resistance problem by placing over-reliance on the few remaining active ingredients.
BASF’s Rob Gladwin encouraged growers to voice their concerns on the potential loss of key azoles by taking part in the ongoing public consultation and highlighting the impact that it will have on their farm.
“There is an opportunity put industry views into the consultation and if we can get as many growers to explain the economic damage it could cause on their farm, it will hold weight.
“We need to maintain a diversity of azoles and may only end up with one or two unless we get our views across. Having a say is certainly not a waste of time and if you take that view, that’s what will happen,” he said.
You can have your say by going to http://ec.europa.eu/dgs/health_consumer/dgs_consultations/food/consultation_20150116_endocrine-disruptors_en.htm
All the speakers were talking at a recent event to launch the Take Ownership Now (TON) partnership campaign, a new initiative by agrochemical giants BASF and Syngenta to raise awareness and offer advice on combating fungicide resistance.