Disease Force team explores wheat fungicide strategies

Sprayers were working hard on our three Disease Force farms when we made our second visit, with T1 treatments being applied to winter wheat in dry and sunny conditions.

In the second article of three in this series, the Disease Force team, in association with Syngenta, finds out what strategies our growers and agronomists are using to tackle the main disease threats to their crops, and discover more about their individual approaches to protecting yield potential.

Mark Wood, JPF Clay, Fawley Court Farm, Herefordshire

Disease levels haven’t exploded in Mark Wood’s wheat crops in South Herefordshire, so his plans for T1 are reflecting that and giving him some budget flexibility.

Mark Wood

Mark Wood © Hannah Lloyd

At the time of the Farmers Weekly visit, he had considered crop potential, drilling date and disease pressure with his agronomist, Andrew Goodinson of Hutchinsons, and they had agreed on four different fungicide mixes for his crops.

“It’s a bit fiddly this year,” he admits. “There is septoria around, as expected, as well as odd crops with mildew and others with eyespot. But the good weather means there’s nothing too concerning.”

His T0s went on in early April and were based on 1 litre of chlorothalonil, at a cost of just £4/ha. Included with them were grassweed herbicides and early-season plant growth regulators, clearing the way for his T1 tank mixes to be less complicated than usual.


In recent springs, he has spent £30-£40/ha on T1 fungicides. This season, only one of the four scenarios warrants that level of expenditure, with the others all expected to come in at below £30/ha.

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 also: the first Disease Force article

“The most forward of our wheat crops, some Revelation that was drilled at the end of September, has good potential and will get an SDHI in the form of 0.8 litres/ha of Seguris with 1 litre/ha of chlorothalonil, at a cost of about £32/ha,” says Mr Wood.

Competitive pricing influenced the SDHI choice, as Aviator was about £6/ha more, explains Mr Goodinson. “It might have been worth it in a more susceptible variety, but Seguris has good persistence and will do what is required.”

In contrast, late-October drilled JB Diego won’t get an SDHI at T1, nor will his more resistant varieties, Costello and Evolution. Either a Firefly/chlorothalonil mix or a Proline/chlorothalonil combination, which cost about £28/ha, have been scheduled.

“The JB Diego is the most likely of the four varieties to get yellow rust, so the strobilurin component in Firefly is a good precaution and brings in another mode of action. The azole loading is the same as Proline.”

Although mildew is present, it is drying up, so may not be worth treating, Mr Goodinson says.

Hereford mildew

“It’s always an extra cost and you have to make a decision now to prevent it getting on to the ear. It adds just under £10/ha to the cost, so it will only be used on some wheat growing by the river.”

As expected, Costello has got lower levels of septoria, but some eyespot is evident. Again, Mr Wood has decided that it’s not worth using an SDHI and has opted for Firefly plus chlorothalonil.

“It will still realise its yield potential. And it keeps some money in the pot for T2, if needed.”     

Evolution is going to get a Proline/Bravo mix at T1. “It’s very clean. Not using two SDHIs in the fungicide programme saves us £10/ha.”

© Oli Hill/RBI

John Haynes © Oli Hill/RBI

John Haynes, MJ & SC Collins, Harlow, Essex

Despite the lack of rainfall in the past month, septoria could be found in the most forward wheat crops at Lysander Park Farm, one of the three farm sites belonging to MJ & SC Collins, when Farmers Weekly made its second visit.

Manager John Haynes and his independent agronomist, Andrew Blazey of Prime Agriculture, were scheduling T1 sprays according to crop development and disease pressure, with applications to the most forward crops around Easter.

Two distinct strategies based on first-generation and more recent SDHI chemistry were in place – with fast-growing first wheats on fertile sites getting an Aviator/chlorothalonil mix, while the later-drilled crops were waiting to receive a Tracker/chlorothalonil treatment towards the end of April.

“Where we have wheat that is struggling, the potential is disappearing with every additional dry day,” says Mr Haynes.

“Fortunately, others are looking great and are still on course for good yields.”

Warm, dry conditions mean that his T0 sprays went on as planned at the end of March and were based on tebuconazole and chlorothalonil, to manage early septoria and any rust.

Since then, as well as moderate levels of septoria in the canopy, mildew has been spotted in patches and on varieties such as Skyfall, and this has had an influence on the T1 product choice.

“Aviator has the added benefit of some mildew control, as well as ticking all the other disease boxes,” explains Mr Blazey.

“At this stage, you need a crystal ball to know whether the disease is going to cause further problems, but we are avoiding the extra expense of a mildewcide.”

Septoria in wheat

Even so, there’s a £12/ha difference in the cost of the two T1 strategies, with the Aviator mix based on 1 litre/ha coming in at £36/ha and the Tracker application costing £24/ha, Mr Blazey acknowledges.

“We have set out to be more reactionary this year, but have to balance that with having the right products on farm when we need them and keeping the triazole rate up.”

To date, yellow rust has not given them any concerns, despite causing problems in susceptible varieties in the area, he adds.

Spray timings are right on track, with intervals being kept to three weeks. “Crops are tall, but not any more advanced in terms of growth stages, so we haven’t gone early,” says Mr Haynes.

He has resisted the temptation to make any cutbacks, even though he recognises that disease risk has been reducing as the dry weather has continued.

“There’s always the chance that it will turn wet,” he says. “It’s far more difficult to rescue a situation that has gone wrong than it is to stay in a protectant mode.”

Antony Redsell © Oli Hill/RBI

Antony Redsell © Oli Hill/RBI

Antony Redsell, Brook Farm Partnership, Reculver, Kent

Soil moisture levels are currently causing far more concern than disease levels in Kent, with grower Antony Redsell describing the very dry spring conditions as severe.

As a result, he and his independent agronomist, James Rimmer of CCC Agronomy are making last-minute changes to their plans, as they deal with a range of crops, including some that are uneven and stressed.

“There are so many variables this year,” says Mr Redsell. “The weather may have taken some of the urgency away, but it is causing us problems with tank mixes and spray timings. And our second wheats are really suffering from the lack of rain.”

His T0s went on in the first week of April, with the varieties being treated according to their disease resistance ratings. Chlorothalonil was applied to Trinity, while Skyfall and Crusoe received Timpani and Cordiale was treated with Cherokee.

“Those choices largely reflected where there was a rust threat, so we added an azole or two if that was likely,” explains Mr Rimmer.

His T1 recommendations have had to be fluid as the dry conditions have continued, with more changes being made to PGR components than to the fungicides and all crops getting two applications of manganese.

“We haven’t cut back on our T1 fungicides, but we have adjusted our timings. Normally, we would be out here in a hurry at this stage,” he explains.

His caution is based on the need to keep the gap between T1 and T2 to three weeks, which would be stretched by jumping the gun with the T1 and could create problems.

Even so, spraying was under way when Farmers Weekly was on the farm, as forward crops of Cordiale had yellow rust appearing in obvious patches.

Yellow rust kent

An Adexar/Tracker mix, with both products going on at 0.75 litre/ha, plus chlorothalonil, had been applied at a cost of about £36/ha.

“We’re going to have to remain vigilant and watch for yellow rust on this crop, as we have never seen Cordiale so badly affected,” says Mr Redsell.

Later-drilled Skyfall and Crusoe were much cleaner, with only low levels of septoria and a bit of mildew being evident, and were due to receive their T1s in the coming week.

Different tank mixes are planned for the varieties, according to their disease profiles and responsiveness to fungicides. Crusoe, with its brown rust susceptibility, will get 1.5 litres/ha of Nebula, so that there is a strobilurin to help with brown rust. The cost will be about £32/ha.

On Skyfall, they have opted for Keystone plus chlorothalonil, as the variety responds well to SDHIs and will benefit from the persistency it provides. Including plant growth regulators, the cost will be about £35/ha.

“If there are any savings to be made this year, they will come later,” says Mr Rimmer. “We can’t take that risk now.”

Experts’ view: Beware of two wheat disease myths

There are two potential pitfalls to avoid with disease control strategies this year, and all three Disease Force farms are managing to do just that, say our independent experts.

The first is the belief that if crops are tall, they are very advanced and need early attention; the second is that the dry April conditions mean that it will be a low-disease year.

“These are both myths,” says Bill Clark, technical director of Niab Tag. “Starting with the first, plants aren’t as advanced as originally thought.

Active ingredients

  • Seguris/Keystone – isopyrazam + epoxiconazole
  • Aviator – bixafen + prothioconazole
  • Firefly – fluoxastrobin + prothioconazole
  • Proline – prothioconazole
  • Timpani – tebuconazole + chlorothalonil
  • Cherokee – chlorothalonil + cyprconazole + propiconazole
  • Adexar – fluxapyroxad + epoxiconazole
  • Nebula – boscalid + epoxiconazole + pyraclostrobin

Height versus growth stage

“Despite their height, most crops are still at the growth stages that we would expect for this time of the year, so there has been no need to spray them early.”

Low night-time temperatures have prevented them from getting too far ahead, and there is colder weather forecast, he explains. “Remember that it takes 125 day degrees for a leaf to emerge.”

His colleague in the West, Richard Overthrow, points out that high soil nitrogen reserves have helped crops on their way this season, with winter wheats developing a strong vertical growth habit and big leaves.

“As well as the effect on crop size, this has implications for disease spread,” he points out.

“In Herefordshire, we have upright, older leaves rubbing against newer growth, which makes it easy for any infection to be transferred.”

Growers who applied their T1s early in reaction to this may be pushed into extra leaf 2 (or T1.5) sprays, as they will be looking at a gap of five weeks until the flag leaf spray, which is too long, he warns.

“It’s good that all of these farms used a T0 spray, as it gave them some flexibility with the T1 timing and their intervals remain as intended.”

Dry conditions

While the dry conditions in the East are a concern on two of our Disease Force farms, they don’t necessarily mean that it’s a low-risk year or that disease isn’t present, both men insist.

“This is the second myth,” warns Bill Clark. “We have been able to find septoria higher up in the canopy than we expected to, so we can’t assume anything at this stage.

He is reassured that our growers haven’t cut back on fungicides, or rushed out to spray too soon, but have tailored their applications according to what has been seen in the field.

“Where SDHIs are being used at T1 for their persistence and eradicant activity, they have a high-dose azole in with them, so defences are being maintained.

“SDHI choice is less critical at T1 – the differences between them come out at T2.”

Use of more resistant varieties and later drilling dates has helped limit disease, especially yellow rust, which was hard to find on these farms, except in some Cordiale.

“Even so, there’s something odd going on with yellow rust, as it continues to appear in unexpected varieties,” says Mr Clark. “In the past few weeks Niab Tag has received samples from all over the country for testing. So everyone needs to be aware of the threat posed by new races.”

Mildew is making an appearance on all three farms, helped by the dry weather, notes Richard. “Deciding whether to treat it is more difficult, as adding in a mildewicide at T1 is an additional cost and difficult to justify.

“As soon as it rains, the disease will disappear. If you do decide to treat, keep it cheap.”

Sponsor’s message

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  • 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.