A change in the weather just ahead of the all-important flag leaf spray prompted our three Disease Force farms to opt for some fungicide firepower, with both new and existing SDHI chemistry being used at T2 to keep crops clean.
Recent rainfall has allowed crops to finally pick up nitrogen, and with temperatures rising, flag leaf sprays were being applied with some urgency as the teams went crop walking for the last time.
Only where yield potential had obviously suffered were there any plans to trim fungicide rates back slightly, safe in the knowledge that there was still the ear spray to come.
What is Disease Force?
This Farmers Weekly initiative, sponsored by Syngenta, consists of a team of hand-picked experts and farmers who will assess disease risk during the season as well as consider ways of managing septoria, yellow rust and brown rust.
See the Disease Force and Ultimate Guide to Wheat Diseases website.
See the previous articles:
East: John Haynes, MJ & SC Collins, Harlow, Essex
Having had to irrigate 300ha of winter wheat since the last visit in late April, Essex farm manager John Haynes is now planning to maintain both yield and septoria protection with a robust T2 approach based on SDHI chemistry.
At the same time, he is being realistic about crop potential after such a
prolonged dry spell and expects wheat yields to be 20-25% down across the three farms that he manages.
“First wheats still have some promise, but our second wheats have had the stuffing knocked out of them,” he reports.
“They were slow to establish originally and they’ve been up against it ever since.”
His plans for T2, which have been formulated with his independent agronomist Andrew Blazey of Prime Agriculture, take account of the use of irrigation as well as his adjusted yield expectations, but he is resisting the urge to make drastic reductions to fungicide use.
“We’ve had that conversation, but the weather has changed and there would be too much at stake,” he says.
Another consideration is that 180ha of Trinity being grown on a fertile block received a T1.5 spray, to target leaf 2, as there was significant septoria present.
“It was fairly advanced, so it received some epoxiconazole plus chlorothalonil with its Terpal, in the second week of May,” explains Mr Blazey.
With flag leaves almost fully out, the bulk of the first wheats will get an application of 1.25 litres/ha of Adexar at T2, but there are also plans to try just under 200ha with 0.8 litres/ha of the new fungicide, Elatus Era from Syngenta, to see what the most recent chemistry has to offer.
The two treatments come out at a similar price, at around £40/ha, so both men believe it’s a good opportunity to compare them.
“Septoria is a moderate driver this year – rusts are equally dominant. The greater choice of SDHI fungicides this year makes things interesting.”
Otherwise, the second wheats will get either half rate Adexar or a litre/ha of Aviator – as their potential is less.
“They are clean, so we’re dropping the rates a bit and accepting that we will lose some of the persistency, but will remain vigilant going forward,” notes Mr Blazey.
Mr Haynes points out that the sprayer will be back in crops at T3, so crops that need a foliar top-up will be covered then.
“We will be keeping an eye out for brown rust, especially on the Crusoe, as it was bad last year. If it warms up, we could get a late flush of disease.”
South: Antony Redsell, Brook Farm Partnership, Reculver, Kent
Getting disease control right leading up to the all-important T2 spray has been much more stressful for Kent grower Antony Redsell and his independent agronomist James Rimmer this year, despite some help with disease pressure from the weather.
While the combination of dry spring conditions and a deliberate move to later drilling mean that the septoria risk has been lower, it is proving to be a rust year.
“We’ve had to be more flexible with our spraying plans,” explains Mr Redsell. “It’s been very dry, and then very cold at times, so we’ve had to react to fields and varieties accordingly. There have been lots of nuances to deal with.”
As a result, T1 timings on the latest November drilled wheat were put back by a week, leaving a four-week gap between T0 and T1, so that these crops could catch up and reach the right growth stage before spraying.
“That gives us the potential to combine the T2 and T3 on these wheats as we move forward, although it’s not something I like to do normally as it does bring in some risk,” says Mr Rimmer.
Otherwise, the T1s went on as outlined in the last Disease Force article (Farmers Weekly, 28 April 2017), with chlorothalonil added to every mix, and T2s were being applied as we visited the farm in the third week of May.
Although the forecast for the rest of the month does promise some rain, Antony points out that it is still very dry and crops have dropped some biomass.
“We had 5mm of rain in early May, which made a big difference and cheered everything up. Crops haven’t tillered as well as they have in previous years, but otherwise they are looking much better than they were.”
The constant rust threat has prompted them to try some of the new SDHI fungicide, Elatus Era, at T2, with 0.8 litre/ha planned for susceptible varieties Crusoe and Cordiale, where it will be compared to an Aviator/Comet mix.
“It’s the same cost, at close to £36/ha, so it will be interesting to see if we can pick up any differences between them,” explains Mr Rimmer. “It’s certainly a year for adding a strobilurin to Aviator at T2, to help with rust control.”
The remaining milling wheat varieties will get Aviator on the flag leaf, which costs around £32/ha, and should help clear up the mildew that is lingering in the thicker crops, he adds.
Fungicide spend will be approximately £70-£75/ha after the T2 has been applied, so he is hopeful that disease control costs will be lower than last year, when they came in just below £100/ha.
“Unfortunately, we can’t farm with hindsight when it comes to fungicides. The T3s will be cheaper this year, although there’s still a chance that we will have to come back in for brown rust.”
West: Mark Wood, JPF Clay, Fawley Court Farm, Herefordshire
Having made the decision to cut back on fungicides at T1 where appropriate and save some money, Herefordshire farm manager Mark Wood is taking a very different approach at T2.
His view is that this timing is where the money should be spent, so he is blanket treating his four winter wheat varieties with the newest SDHI chemistry and using an 80% rate.
“I’m spending a few pounds more than last year on the flag leaf spray, at around £40/ha,” he admits. “We had a much-needed week of rain just before we started spraying, so we need to maintain the septoria protection.”
Despite this extra expense, he is confident that his total fungicide expenditure will be slightly less than last year and has a target of £100/ha in mind.
Close attention to the timing of the first two sprays means that disease has been confined to the lowest leaves and crops are very clean – although Mr Wood is less pleased with the Revelation at this stage than he is with the other varieties.
“It was the first to receive its T2 spray, despite having been the only one to have a more expensive SDHI-based T1. It has more septoria in it than the others and has developed stress tipping on leaf 3, which may let more disease in.”
Working with his agronomist Andrew Goodinson of Hutchinsons, Mr Wood has decided to opt for Ascra as the T2 mainstay, but is also doing a split field comparison with some Elatus Era, so that they can get some insight into the latest products to the market.
Chlorothalonil hasn’t been added to the T2 spray, as two applications have already been made.
“With two new kids on the block, the choice at T2 has expanded, which is good news,” says Mr Goodinson. “The SDHI/triazole combinations all do a very good job, providing they are applied at the right time.”
Variety ratings do give some flexibility, with some varieties being less responsive to fungicides than others, he accepts.
“But with the rain coming in and most crops still having good potential, we are giving the flag leaf the protection that it will need in the coming weeks.”
Physiological symptoms such as speckling and blotching are being seen, which Mr Goodison suggests are a result of the dry spell inhibiting micronutrient uptake, as well as cold night temperatures.
Another feature of the season is smaller flag leaves on both Evolution and JB Diego, which may yet recover.
Of the four varieties being grown, Costello is the cleanest to date, with only small amounts of septoria showing on leaf 5.
A very even field of the variety is the site of the Ascra/Elatus Era fungicide comparison, with both products going on at full rate.
“They both look very strong,” comments Mr Wood. “Our decision to go for Ascra on the majority of the farm was made on septoria. If rust was causing us problems, we might have come to a different conclusion.”
Experts’ View: All change as weather turns
The tone and the urgency of the fungicide conversations taking place between farmers and their advisers changed completely when the rain finally arrived, agree our experts.
A month ago, when it was very dry and disease levels were low, Niab Tag and Syngenta were asked whether SDHIs were worth the expense and if there were significant savings to be made by using cheaper products and fewer sprays.
As well as questioning the need for more expensive chemistry, farmers were asking about reducing fungicide rates and dropping out or combining spray timings, as they contemplated the loss of yield potential.
As a result, final decisions on fungicide choices and strategies were being delayed to the last minute.
However, this indecision vanished in mid-May, when the wet weather appeared and crops started to pick up again.
At this stage, spraying plans were reappraised, with growers and agronomists reacting to the immediate growth that occurred and the corresponding disease threat.
“Of course the rain hasn’t salvaged everything,” says Richard Overthrow, Niab Tag’s western region agronomist. “There will have been some grain sites and tillers lost, especially on lighter soils or where there was poor rooting.
“But we went from farmers talking about cutting back on fungicides to them asking us about putting on as much as possible as soon as they could.”
He says the discussions the team had just before the T2 timing bore very little resemblance to those that had taken place a few weeks earlier.
Given the change in the weather, he is convinced that higher rates are essential at T2 and points out that any delays to the flag leaf spray will mean that they need to provide as much eradication as possible, to deal with existing disease.
“You’re only going to get that eradicant activity from the SDHI component of an SDHI/triazole mix. The triazoles don’t offer that anymore.”
The new SDHIs, Elatus Era and Ascra, offer 7-10 days’ kick-back, depending on the rate used, compared to just one day from the triazoles, he reveals.
- Elatus Era – Solatenol (benzovindiflupyr) + prothioconazole
- Ascra – bixafen + fluopyram + prothioconazole
- Adexar – fluxayroxad + epoxicoanzole
- Aviator – bixafen + prothioconazole
“They are a step forward for most situations, not just where there’s been a delay. If you need convincing about their strengths and suitability for your farm, try some out alongside your standard programme.”
Mr Overthrow stresses that the flag leaf works like a solar panel. “It is the power house when it comes to building yield, so we need to keep it working well.”
Harry Fordham, area manager with Syngenta, says here crops are clean, the advice is to add chlorothalonil to Elatus Era, as it gives extra septoria protection and fulfils stewardship obligations.
In the West, his colleague Mel Codd points out that only where there are delays to the flag leaf spray should the chlorothalonil be omitted.
“In a protectant situation, its adds to the party and brings an improvement in septoria control. Otherwise, it’s a resistance precaution.”
Our Disease Force farms have all seen tiller loss and are coping with less even, shorter crops as a result of the dry spell, with some acknowledging that yields will be down on disadvantaged sites.
But with just under two months to go until harvest, all were reasonably confident that they had the right foundations in place for most crops to make up for lost time.
As a result, they have taken no chances with their T2 applications, using some of the best SDHI/azole chemistry available and keeping rates up.
Bill Clark, technical director of Niab Tag, is pleased to see that so much attention has been paid to the accuracy of spray timing, as the disease risk has not been as low as many believed it to be.
“It’s surprising just how much septoria and yellow rust is around,” he reports. “Earlier on in the year, there was a lot of talk about crops being forward, so there will have been leaves or parts of leaf that had been out for a long time, so were exposed to infection.”
He warns that crops picking up nitrogen and putting on growth are just the conditions that disease favours. “Yellow rust in particular will love it, as it has to have living tissue to thrive.”
Fortunately, product choice at T2 is very good and has been boosted by the addition of two new SDHIs this year, which have shown disease control and green leaf area benefits over existing materials in trials, he notes.
Tight spray intervals
Mr Clark accepts that there has been scope to cut back this year, as disease pressure has been lower. But he highlights the results of Niab trials, which support the use of programmes based on better chemistry and tight spray intervals, regardless of the conditions.
“We looked at 90 comparisons, using 10 varieties being grown across three sites and three years,” he says. “We used a more expensive programme, based on two SDHIs at T1 and T2, versus an older boscalid/triazole-based programme, which was £52/ha cheaper.”
The main finding was that it was more profitable to use the more expensive programme on all the varieties in every season.
“Spending £52/ha more and getting no benefit was the worst that could happen. But saving £52/ha with the basic programme often resulted in a yield loss that was worth far more than that.
“When it goes wrong, you end up with a big problem. That’s why combining the T2 and T3 spray is very risky.”
Work is being done on different septoria strains, as a new strain was found on Cougar two years ago, which seems to cause more disease on susceptible varieties, he reveals.
“It’s not difficult to find and it is a concern. It is more resistant to triazoles.”
With slightly lower disease risk in the East, Anthony Slade of Syngenta reports that most of the Elatus Era is being applied at 0.8 litre/ha, although the full rate is 1 litre/ha.
“The variety being grown will have a bearing on rate, as will the presence of any existing disease.”
Syngenta is committed to driving innovation and class-leading crop protection solutions.
This is a direct result of major and sustained investment into its unique R&D product pipeline that responds to market needs and a commitment to support farmers in protecting crops from devastating pests and diseases.
New for this season, Syngenta’s T2 SDHI cereal fungicide, Elatus ERA, is proven to deliver powerful and consistent broad-spectrum control of septoria and rusts.
- Thanks to Syngenta, whose sponsorship made it possible to run the Disease Force Cereals visits. Farmers Weekly had full editorial control of this article. See all of our wheat disease articles on the Wheat Disease website.