Suffolk wheat grower Richard Duchesne looks to select an early fungicide spray with a good broad-spectrum of disease control, and is pleased with his first use of the new SDHI Iblon at keeping yellow rust and septoria at bay.

He used the new fungicide in its first year of approval in 2024 in a mixture with two azoles at the T1 stage in late April across all his wheat, and the result has given him confidence to look at using it again this spring.

His aim is to keep feed winter wheat fungicide spend at £120-£130/ha, largely focused on a two-spray programme. He was impressed by the way his comprehensive T1 set him up well for choosing a later T2 spray.

See also: How the latest fungicides fit with barley ramularia control

“I can see us using Iblon again at the T1 stage this season due to its broad-spectrum disease cover, if it proves value for money,” says Richard.

Champion winter wheat © David Jones

He is growing newer feed wheat varieties such as Champion, Beowulf and Typhoon with generally good genetic disease resistance to minimise the need for a rust-specific T0 fungicide and keep overall costs under control.

Last harvest, one of Richard’s first wheat crops, which was drilled during late January after sugar beet, touched a yield of 11.5t/ha, beating his five-year average of 9t/ha, which he puts down largely to good early disease control.

Iblon, being sold under the brand name Vimoy, plus its recommended azole partner, prothioconazole, will compete with other fungicide mixes such as Miravis Plus + Era, Univoq and Revystar this spring and all are likely to cost more than £50/ha at recommended rates.

They will also compete against older products, such as Ascra and Elatus Era.

The SDHI Iblon can be used only once in a season, either at T1 or T2, but many agronomists believe it will be used mainly at T1 due to its broad-spectrum disease control, while specialist septoria products such as Miravis Plus and Univoq may be used more at the T2 stage.

Septoria in winter wheat © David Jones

Growers can only use 75g/ha of the active isoflucypram (Iblon) over two successive years, which at recommended rates will likely rule out its use on a second cereal, as a recommended Vimoy rate of 1 litre/ha will contain 50g of isoflucypram.

Bayer launched Vimoy last season in a twin-pack with the azole prothioconazole, while for this season the agrochemical giant has also added a new three-way mixed formulation with an extra SDHI fluopyram, called Plaxium.

Plaxium is a similar three-way mix to the group’s Ascra fungicide, with the new SDHI Iblon replacing the older SHDI bixafen in Ascra.

T1 strategy

Richard’s philosophy for T1 fungicide sprays is to look for a broad-spectrum product to control his main disease threats of yellow rust and septoria, while a later T2 spray can be more focused on diseases likely to be prevalent later in the season.

He grows 500ha of feed wheat and 180ha of milling wheat on the 800ha that he and his family farm at Hall Farm, Stanningfield, on owned and contract farmed land, six miles south of Bury St Edmunds.

This is alongside sugar beet, oilseed rape, spring barley and winter beans on largely medium clay loam soils.

Richard Duchesne © David Jones

His experience of growing the yellow-rust susceptible variety Skyfall has made him very focused on the threat of rust, and for this season he has switched most of his milling area to the newer and more yellow rust-resistant milling variety Cheer.

After using a T1 and T2 of a Myresa (azole mefentrifluconazole) and Syrex (SHDI fluxapyroxad and
strobilurin pyraclostrobin) mix in the 2023 season, he was keen to try some new chemistry to his boost disease control for 2024.

Last season

In 2024, his feed wheats generally didn’t receive an early T0, and then he used Vimoy at 1litre/ha along with its chosen partner, prothioconazole, and added another azole, tebuconazole, to give a quick knock-down effect on any yellow rust present.

He kept his Myresa-Syrex approach at the flag leaf T2 stage and again added tebuconazole to boost rust control, while only his milling wheats had a T3 head spray of prothioconaozle.

“We were pleased with the Iblon mixture for disease control and it fitted in well with our 2024 fungicide programme. Yellow rust is my key worry, especially after growing a lot of Skyfall,” he adds.

Richard points out that T1 sprays largely act in a protective way against disease, so it is important to get the choice of products right to give good activity against septoria and yellow rust, and also against any possible brown rust infection.

His disease control was good in the high-disease season of 2024, with yellow rust and septoria largely controlled on the upper leaves by his T1 and T2 treatments.

He has not made his final decision for a T2 treatment this season, but will make his choice based on the main disease threats at the flag-leaf stage in late May.

• Next week we travel to Dorset to find out about one grower’s experience of using Syngenta’s new Miravis Plus fungicide.