Battling with brown rust: A grower’s reflections on 2024

About Ollie Cook and Shillingford Farm

Shillingford farm, Oxfordshire © BASF

• Name: Ollie Cook, partner in family business & Technical Agronomist at BASF
• Farm: S M Cook, Shillingford, Oxfordshire
• Farm size: 350 ha of combinable crops
• Rotation: Wheat, then winter barley or a second wheat, OSR, wheat, spring barley spring beans.
• Wheat establishment method: Min till, then discs to get a chit of blackgrass, Amazone Cayena drill into stubble.
• Wheat varieties 2023/24 and their RL brown rust rating: Crusoe (3), KWS Extase (7), KWS Palladium (6), KWS Dawsum (7).
• Wheat varieties 2024/25 and their RL brown rust rating: SY Cheer (6), Skyfall (8), KWS Extase (7).

Whilst both yellow and brown rust are no strangers on Oxfordshire based Shillingford Farm, last years’ brown rust epidemic was another level.  

Ollie Cook noted: “Both Crusoe and KWS Extase got brown rust in late February and even back then, it was quite severe in places.

“It was certainly unusual to see brown rust in that quantity so early on, as it is typically considered to be a late season disease.

“The other watchout for me was how quickly it was cycling, which added to the challenge.”

© BASF

Varieties

Ollie grew Crusoe for milling last year. “We made the protein but struggled on the specific weight because the high brown rust pressure resulted in smaller grains. It was the Crusoe where we really had a battle.

“KWS Palladium and KWS Dawsum stayed clean all season and thankfully we managed to control the rust in KWS Extase, once we had started the fungicide programme.

“This season, as part of an integrated pest management (IPM) approach, I have had to think about the varieties I choose.

“So I have decided to drop Crusoe and am trying SY Cheer, a new Group 1 which has better brown rust resistance. If it compares favourably to Skyfall then I will probably look to increase the area of SY Cheer next year as it is a cleaner variety.”

Jonathan Blake, technical director for crop protection, ADAS agrees with Ollies approach, saying:

“One of the main pillars of IPM is to grow resistant varieties, however, most conventional wheat varieties are moderately susceptible or susceptible to brown rust.

“We normally don’t have to worry about brown rust in varieties that have a Recommended List rating of 5, 6 and 7 for brown rust, because usually what we do for septoria at T1 and T2 will also control it.

“It’s when brown rust gets in early that it can be difficult. Once established in a crop it is very difficult to remove. At this point it’s just a case of dampening it down for the rest of the season.”

Fungicide programme

In Oxfordshire, Ollie made a timely T0 application of tebuconazole on the 2^nd of April to his crops of KWS Extase and Crusoe.

Reflecting on last season, Ollie commented: 

“On the KWS Extase, the tebuconazole at T0 proved very effective on the brown rust and managed to keep it under control to the T1, and from here we managed to keep it out all season.

“However, this approach was not so successful on the Crusoe.

“By the time we got to T1 we went in with more tebuconazole along with an SDHI + prothioconazole based fungicide, but because we were in an eradicant situation we didn’t ever get on top of it and the pressure remained high for the rest of the season, with the brown rust really exploding after T3.

“But honestly, the crop was on its way out by then.”

Jonathan Blake said: “It is only in seasons like the one just gone, where the epidemic gets accelerated with favourable conditions, that we have had to worry about brown rust early on.

“If it is present in March or April, we need to be applying effective chemistry at T0 and trying to keep it under control from there. In more ‘normal years’, on susceptible varieties, keeping the disease in mind at T1 and T2 is sensible.

“Ensure that whatever SDHI, azole combinations are used at the T1 and T2 timings for septoria, are also effective on brown rust.”

Fungicide selection

Jared Bonner, Business Development Manager, BASF said:

“It’s alright thinking you have a broad spectrum fungicide in your tank but you need to be sure it is a fungicide that targets the important diseases at T1 which are septoria, yellow rust and based on last season, brown rust. Revystar XE does just that.”

Jared Bonner © BASF

Jonathan Blake said, “Revystar XE contains fluxapyroxad (Xemium) and mefentrifluconazole (Revysol) both of which have good activity on brown rust.

Mefentrifluconazole also has good activity on septoria, and so it may fit well on varieties where brown rust is a concern, like Champion.“

Yield losses

“When brown rust epidemics occur early yield losses can be very large.

“Although yield losses to brown rust can be difficult to quantify in isolation, every year in the Recommended List trials we look at treated yields versus the untreated.

“This gives a crude estimate of what the yield response to fungicides is.

“Usually the yield response is about 2.25 t/ha, last year it was 4.9 t/ha, more than double. Brown rust would have been a big factor in that,” said Jonathan Blake. 

Winter temperatures gave brown rust a head start

Last year, conditions through the winter were a degree or more above average from October to March.

“That made a huge difference to the latent period of brown rust; it meant the disease was cycling in two weeks rather than three, which built up the early inoculum.

“Then, when conditions started to get more favourable as spring warmed up, the brown rust effectively had a head start,” said Jonathan Blake.

“Cold winter weather doesn’t directly kill brown rust but it is a biotroph, so needs living material to survive.

“Through the winter, brown rust is clinging on, trying to infect recently emerged leaves from its position on the lowest leaves.

“Its infection efficiency is very poor and its latent period is very long so it struggles to keep ahead of the turnover of leaves that happens through winter.

“If you have a particularly cold spell the lowest leaves can be killed out, taking the brown rust with them and reducing the level of inoculum in the crop.”

Brown rust this season

© BASF

This season, up until December, temperatures were similar to last year, however, January and February have been much closer to, or slightly below average.

“The early season brown rust threat will be dependent on the weather in March and April, which has the potential to make an enormous difference.

“If these months  are exceptionally warm, we could have a problem, ” said Jared.

For more information on Revystar^® XE, please visit the Revystar^® XE product page: Revystar XE – BASF Agricultural Solutions UK