Analysis: Can farmers be less reliant on fungicides?
© Tim Scrivener Cereal growers looking to reduce their growing costs are increasingly questioning the need for four-spray fungicide programmes.
With the focus on many farms shifting to soil health and sustainable farming methods based on making the most of soil biology, the routine use of chemical inputs is being scrutinised more closely than ever before.
While economics and environmental gains are key drivers for change, there are many other factors having an influence on decision-making and the desire to be less reliant on the chemical can.
Those include active ingredients being lost at an accelerating rate, key modes of action breaking down to resistance and the introduction of new, less responsive varieties, with better disease resistance.
Added to these, agronomic practices and rotations are evolving as soils take priority.
Later drilling dates, greater use of spring crops and a more diverse mix of cropping is reducing disease levels found in crops.
See also: Analysis: What a ban on fungicide chlorothalonil would mean
For many, the hot, dry weather in 2018 was a turning point – it was the perfect year to grow crops without fungicides.
Septoria development was interrupted and hindsight told growers that they should have stopped spending long before they did.
For others, reducing chemical inputs started some time ago, with the recognition that having a healthier soil helps to produce plants that are less likely to get disease and have less need for chemicals.
More sprays
The number of sprays required in a season has crept up gradually, acknowledges Jonathan Blake, principle research scientist at Adas, and it would be wrong for growers not to consider whether they need to continue with such a comprehensive approach.
“There’s talk of two-spray strategies for some situations now and it can be done,” he says.
“Planning to cut back to a two-spray fungicide programme is not as risky as it may seem.”
He recognises that it’s a leap too far for some and won’t be appropriate in some scenarios, especially after a mild winter.
However, he points out that a high input approach is unlikely to be needed on the newer, more resistant varieties, especially where they have been sown later.
“In these situations, you don’t need to spend as much on disease control. There’s already a buffer in the system.”
In his view, a two-spray strategy is most suited where feed, rather than milling, varieties are being grown and where there’s good resistance to both yellow and brown rust.
“A low risk of fusarium is another requirement of this type of regime,” he says.
It could also work well where crops are late sown, if the wheat price is low and where yield potential is limited, he adds.
“There are various possibilities. We know that the yield benefit of a T3 spray is in the region of 0.2-0.3t/ha, so by strengthening the T2 spray, the response could be less.
“That would make the T3 marginal. Of course, it will also depend on the wheat price.”
Bill Clark, technical director of Niab Tag, is of a similar view.
“We are seeing the introduction of low-risk varieties that will only need one highly eradicant spray in a season.
Suitability for a two spray strategy?
- Feed wheats
- Late-sown crops
- Low risk of yellow and brown rust
- Low risk of fusarium
- Limited yield potential
- Fall in wheat price
“That makes a two-spray programme a real possibility. These types are never going to give the same response to fungicides that susceptible varieties do.”
Loss of actives
The loss of active ingredients – some of which don’t have obvious alternatives – is also prompting farmers to think again, he adds.
“The older products that are being lost tend to be the cheaper ones. When replacements for them have to be considered, they invariably have a higher price tag.
“That concentrates the mind. The T0 spray is one that is likely to come under fire – without chlorothalonil to use, a T0 is set to cost more.
“As there’s rarely a yield response to it, it could become an expensive insurance policy.”
Seasonal fluctuations will always have to be accommodated, whichever number of sprays you decide on, he notes.
“Any active yellow rust early in the season is a concern, for example.
“Decisions will always have to be made on what you see in the field, as well as on variety and drilling date.”
Case studies
Colin Chappell, Chappell Farms, Lincolnshire
The AHDB’s Brigg Monitor Farmer Colin Chappell is hoping to start the transition to a more biological approach and reduce the number of fungicide sprays he uses in 2019.
Having gradually increased from using just a T1 and T2 spray some years ago to a full four spray programme in 2018, he is now hoping to drop one spray and try to reduce both his expenditure and reliance on fungicides.
In preparation for that, he has drilled his wheats later and used higher seed rates, while opting for more resistant varieties where end-user contracts allow.
He is also paying far more attention to his soils, so that they can play a fundamental role in supporting healthy plants that give consistent yields.
Soil health
“We are getting our soils in better condition by cultivating less, using cover crops to build up organic matter and getting the drainage right,” he says.
“There’s no doubt in my mind that by putting some biological life back in to the soil, we will be less reliant on chemical inputs and more able to sustain healthy crop growth.”
As he grows milling wheats, he is reluctant to drop the T3 or ear spray, for fear of exceeding mycotoxin limits in a wet year.
Instead, he hopes to omit the T0 spray and change his fungicide product choice at T1 and T2.
“We go through the crop at the T0 timing with trace elements and plant growth regulators, so the temptation has always been to put some chlorothalonil in with them too,” he explains.
“Whether it’s really needed depends on the season, but I’m sure we could manage without it.”
The fact that chlorothalonil has been banned by the EU after 2020 will force him to make that decision next year, he admits.
Historically, Mr Chappell has used an SDHI at both T1 and T2, finishing with an azole mix at T3.
This year, he is planning to use an azole and chlorothalonil mix at T1 and only include an SDHI in the flag leaf spray.
T2 importance
“The T2 spray is the most important timing, so we’re saving some firepower for that.”
He stresses that he can’t make firm plans too far in advance because he doesn’t know what the season is going to bring.
“But we have taken steps to reduce disease pressure by drilling later.”
Mr Chappell is Basis qualified, so does much of his own agronomy and uses both leaf and sap testing to help with decision-making.
Growing Crusoe means that he has to keep an eye out for brown rust, but his other variety choices – Revelation, Elicit and Gravity – have better resistance ratings.
“Reducing our fungicide use is the aim, so we are taking the first steps in that direction,” he says.
“If we can successfully combine that with regenerative soils, there’s no reason to believe that yields won’t suffer.”
Andy Howard, Bockhanger Farms, Kent
Input reduction, not just fungicides, has been part of a larger strategy at 300ha Bockhanger Farms near Ashford in Kent since 2012.
In an ambitious five-year plan, grower Andy Howard set out to reduce artificial inputs by 50%, with both fungicides and nitrogen in his sights and an intention to cut out insecticides completely.
With holistic management as his guide, he stresses that there is no magic bullet and that it’s a systems approach that allows changes to be made, with consideration always being given to soil health and the impact of any actions on the soil.
Diversity
“The key is diversity,” he says. “If you want to farm with minimal inputs, you have to strike a balance between healthy soils and plants.
“Encouraging the soil biology is essential – the system then has a chance of being self-regulating.”
His approach seems to be working. This season, he won’t be using any seed treatments, plant growth regulators or insecticides and fungicides will only be applied at T2 and T3.
Just 140kg/ha of nitrogen fertiliser will be applied to his milling wheats, unless plant testing indicates that more is required, along with 80kg of potash in the spring.Foliar nitrogen is used at T1 and T2, for its greater efficiency.
Mr Howard started his conversion to a biological system by introducing no-till, before bringing in cover crops and integrating livestock.
He also uses companion cropping, has perennial crops in the rotation and is continually improving soil health.
Monitoring is now an important part of his farming approach. In-depth soil analysis plays a key role in keeping nutrient ratios at the right levels, while a biological test gives him figures on nutrient release in a growing season, allowing him to reduce nitrogen accordingly.
As a result, he is now using 40% less bagged nitrogen that he used to and is still achieving wheat yields of at least 9t/ha.
“The biggest payback comes from the first 100kg/ha of nitrogen,” he says.
“If you put too much nitrogen on, it can affect the levels of potash, copper and boron that are available to the crop.”
Weekly monitoring
Crops are monitored every week in the growing season, with sugar levels in plant sap guiding the need for fungicides. He also measures sap pH, for plant health reasons, and uses an N tester to gauge chlorophyll levels.
In terms of foliar applications, Mr Howard doesn’t use a T0, unless some nutrition is needed.
At the T1, T2 and T3 timings, he applies biology and nutrition, which allows him to reduce fungicide use by 40%.
N-fixing and phosphate solubilising microbes are added to farm-saved seed at drilling, which fixes 30kg/ha of nitrogen.
He has previously used a biostimulant to get the crop to grow away quickly and applies a home-brewed biological tea to feed the soil biology.
Other treatments include a humic and fulvic acid product for beneficial microbes and silicon, to help with disease resistance and lodging.
This year, he is trying a soil conditioner based on orange oil, for its potential help with water infiltration.
Novel products are helping to get through the transition phase, rather than becoming essential inputs.
“If it’s not cheaper, I won’t do it,” he says.
His wheat variable costs are £350-400/ha, depending on the need for herbicides, the use of Fibrophos and any hand rogueing.
“Balanced, healthy plants are less likely to get disease,” he says.
“Where high rates of nitrogen are used, it’s difficult to reduce fungicides, so the system has to change if you want to make savings.”
Lower fungicide inputs – is it for you?
An on-farm demonstration of managed lower fungicide inputs is on the agenda at the next AHDB Strategic Farm East open day, which will be held on 6 June 2019.
Hosted by Brian Barker at Lodge Farm, Westhorpe, near Stowmarket, the project aims to bridge the gap between research and practical farming, providing a programme of demonstrations that have been subject to a full net margin cost-benefit analysis.
One of the themes for 2019 is harnessing varietal resistance to manage fungicide spend.
To this end, the effect of reduced fungicide applications and cost of production on varieties with different resistance ratings is being investigated.
High, medium and low fungicide input programmes are being compared across five winter wheat varieties.
Two of these, Silverstone and Santiago, are traditional barn-fillers, while the others, Graham, Shabras and Siskin, have better disease resistance and should offer scope for savings.
Assessments will be made for foliar diseases at T0, to determine over-winter disease pressure, and then again at T1 or growth stage 32, and T2 or flag leaf emergence.
After that, there will be assessments done three and six weeks later, with ear diseases and stem-base disease also being scored.
Growers wishing to attend the open day and find out more about reducing fungicide spend should visit www.ahdb.org.uk to register free for the event.
