What the latest fungicides bring to wheat disease strategies
© Tim Scrivener Arriving at different stages of the season and in various guises and quantities, both Bayer’s Iblon and Syngenta’s Adepidyn were available for the first time in 2024.
This brough two new SDHIs into the mix in what turned out to be a high-disease pressure year.
First to arrive was the active ingredient Iblon (isoflucypram), which was sold as Vimoy + Proline 275 (prothioconazole).
See also: New cereal fungicide gives strong performance in AHDB trials
It was approved well ahead of the growing season and is available widely.
In contrast, Adepidyn (pydiflumetofen) came to the market as Miravis Plus + Era (prothioconazole), only just in time for the T2 spray and in limited quantities.
Just how much of the latter was used on-farm is hard to get a handle on, as many growers had already made their plans and secured their flag leaf products before its launch.
It also raised the bar with a slight premium over existing T2 offerings.
However, its pre-launch reputation as a game changer meant there was an acceptance within the industry that Adepidyn would come to dominate the T2 market if money was no object.
Actives
- Vimoy Isoflucypram (Iblon)
- Proline 275/Era Prothioconazole
- Miravis Plus Pydiflumetofen (Adepidyn)
- Revystar Fluxapyroxad + mefentrifluconazole
- Ascra Bixafen + fluopyram + prothioconazole
- Elatus Era Benzovindiflupyr (Solatenol) + prothioconazole
- Inatreq Fenpicoxamid
- Solatenol Benzovindiflupyr
Crowded market
As a result, it is likely the T1 market will become more crowded, suggests Chris Bean, technical director of Zantra.
He points out that there were several existing fungicide options with a dedicated following before Iblon joined them.
“Growers and agronomists were already familiar with products such as Revystar, Ascra and Elatus Era for the T1 slot and had the knowledge and experience of how to use them,” he says.
Iblon arrived as a slightly more expensive T1 option, so it had to fight for its place in a strong line-up.
There was also loyalty to Corteva’s Inatreq, he notes, but it had been more widely used at T2 up until then.
© Blackthorn Arable
Learnings from 2024
The main learnings from the season were that where septoria is concerned, Adepidyn is the most effective material at T2, reports Chris.
“In terms of the combination of septoria control, green leaf retention and yield, it’s the best,” he says.
“It comes at a premium, depending on what it’s compared to, but in our trials it took the top spot in every position we tested it in. It also looks to have some activity against fusarium species.”
Close behind it at T2 is Inatreq, he continues. “Again, where septoria is the target, it’s very good and comes extremely close.
“Importantly, it also brings a new mode of action to the party, which is so important in terms of resistance management.”
Having said that, Chris stresses that no products are 100% bombproof and he highlights that both options need partners to control rusts.
“In 2024, many found out that brown rust needs more thought and even yellow rust needed help in such a high-pressure season.”
Different partners were certainly put through their paces, but in the end, the programme adopted was the most important factor in terms of success.
“In my experience, all of the new actives work better when partnered with an azole, and where rusts are concerned, the addition of a strobilurin makes a very big difference.”
In contrast, Iblon is better on rusts compared with the other new entrants, says Chris.
“In T1 trials, it performed well, especially against yellow rust, similar to Solatenol that we have been using for a number of years.
“We need more experience with it at T1,” he adds. “There are claims being made about its eyespot activity which also give it a fit at this timing.”
The 2025 season
Looking ahead, Chris advises that fungicide choices for 2025 will depend on how much growers want to spend, as well as what the weather does.
In most situations, he recommends that growers have either Adepidyn or Inatreq at T2.
“If you are growing a susceptible variety in a high-risk septoria situation, then the best sequence is going to be Inatreq at T1 and Adepidyn at T2,” he stresses.
“It’s not the cheapest, but in a trials situation it delivered 0.25-0.5t/ha more yield.”
When it comes to rates, there’s always a temptation to drop them with premium materials, Chris acknowledges, but it puts yield at risk.
“Once you go down that route it gets harder to pick up differences in disease control.”
With Adepidyn, there’s a significant difference if you go below the 1.5 litres/ha rate, he warns. “You don’t see the same green leaf area retention or yield at 1.25 litres/ha, so it’s a false economy.”
On Zantra’s Kent variety site, a four-spray programme containing Adepidyn at T2 cost the equivalent of about 0.7t of feed wheat, with the mean response across a range of varieties being 3.6t/ha.
“So while cost control is understandably at the top of the agenda, fungicide programmes will still give a good return.”
Prothioconazole concerns
As both latest additions are partnered with prothioconazole in their offer, there’s understandable concern about the azole’s future as it comes under pressure.
“The more exposure it gets, the more we worry about resistance,” says Zantra’s Chris Bean.
“The arrival of Inatreq was a relief, as it gave us a new mode of action and could be part of a good anti-resistance strategy.
“Mixing and matching with Inatreq in the programme reduces the risk.”
Adding tebuconazole to prothioconazole makes some sense from a resistance perspective, he adds, as well as using some folpet to lessen the threat.
Brown rust control
Yet again, the T0 spray played a central role in the success or failure of brown rust control in 2024, reports Zantra’s Chris Bean.
Early spray timing has never gone out of fashion in Kent – a recognised brown rust hotspot.
However, it has been dropped by growers in recent years, who were more focused on septoria control and counting on later drilling dates to keep infection levels low.
Last year, a 1t/ha difference was seen in susceptible Crusoe wheat where it was left untreated until T1, compared to where a T0 was used, emphasising the importance of being ahead of brown rust.
“It’s a disease that needs thinking about at T0,” says Chris. “Hopefully, the colder winter conditions will help this year, but we know we can’t be complacent.”
He adds that there are plenty of varieties which could easily develop significant yellow rust this spring, given the later drilling of crops caused by the wet spell from late September to mid-October.
There is also now a strain of brown rust that has been identified with a genetic mutation that makes it less sensitive to the SDHI fungicides.
“However, it is very fortunate that both the azoles and in particular, the strobilurins, are still highly effective, so adding them to the treatment is advisable” he recommends.
“With brown rust, you need to start as early as possible and use mixed chemistry.”
