No septoria resistance was detected to QiI fungicides, like Inatreq, last year despite a wet and mild spring leading to very high septoria pressure in 2024.

Steven Kildea told the National Tillage Conference that although winter wheat crops were quite dirty last year, this was due to the very high disease pressure and the fact that it was very difficult to apply fungicides at the correct timing.

This is positive news for the tillage sector and gives confidence in QiI fungicide efficacy against septoria for the coming season.

However, when it comes to some of the older chemistry, Kildea explained that “there is a continual erosion of sensitivity to the SDHIs and the azoles. There’s nothing new there, it has been happening for the last 15 years. It hasn’t gotten significantly worse, but it’s something we’re keeping an eye on.”

To help farmers choose fungicides for disease control, Teagasc has produced fungicide star ratings (see image) to give an indication of the efficacy of different products. Trials were conducted where one application of each fungicide at full rate was applied at the flag leaf stage.

Looking at the graph in Figure 1, Univoq, which contains Inatreq, a QiI fungicide, remains the most effective fungicide on winter wheat for septoria control, giving nearly twice the yield response of the next best fungicides.

“It’s still not absolutely perfect,” added Kildea, leading to a score of four stars out of five.

Revystar XL had a high level of efficacy at the beginning of 2024, but Kildea noted that this dropped off throughout the year, and it was reflected in the yield response. The product is now very similar to Ascra Xpro in its efficacy against septoria, when it would have had a higher efficacy in previous years.

When it comes to multisites, folpet and sulphur (Thiopron) perform quite weakly, with poor disease control and a low yield response. However, Kildea explained that this is due to the design of the trial. In a commercial crop, he expects these multisites to be around 2.5 stars, in addition to protecting the remaining fungicides from resistance. He reminded farmers that IPM (integrated pest management) is not just about disease control and reducing fungicide use, it also involves trying to prevent resistance building up to the chemistries that we still have available.

Their similar performance means they can both be used in a fungicide programme. With only two applications allowed of folpet each season, Kildea suggested that sulphur can be used in an early-season application where there is high septoria pressure, but that this is regarding sulphur products that are registered as fungicides rather than any nutritional sulphur products.

Barley

When it comes to barley, Kildea saw high levels of ramularia, rhynchosporium, brown rust, and net blotch in trials. These disease populations showed that the net blotch population is dominated by the F129L mutation which is resistant to specific strobilurins, and that ramularia has some SDHI, strobilurin, and azole resistance, which can affect the efficacy of some products.

However, despite this, Kildea noted that there was good overall control of barley diseases in 2024. Star ratings were also produced for fungicides applied to barley, and the focus in Figure 2 is on ramularia.

Revystar XL and Macfare Xpro were the top performing products, achieving three stars and nearly 60% control of ramularia.

Siltra Xpro, Elatus Era, and Prothioconazole all achieved two stars. This shows that the additional active ingredients in Siltra Xpro and Elatus Era, which also contains prothioconazole, are not providing any additional protection against ramularia over prothioconazole by itself.

However, Kildea noted that they are effective against other barley diseases and can be included as an important part of a disease control programme.

“You need to mix and match the different modes of action to reflect the disease pressures that are there,” he said.

Folpet and sulphur are shown to perform poorly against ramularia.

Kildea commented that there is not enough research on sulphur in barley crops so far, so folpet is still required. While it may not control ramularia, it protects the other chemistries used against resistance and can give additional control as part of an effective disease control strategy when applied at 1.5l/ha. While these rankings are a useful tool for farmers for wheat and barley, Kildea reminded the audience that spray timing is critical.

“We need to make sure that we are applying these chemistries at the optimal timings from an activity perspective,” Kildea said. “The upper canopy is where we capture yield,” and correct timings will protect the upper canopy to maximise yield potential.