Broad-spectrum ascra boosts barley disease arsenal

The convenience of having a broad-spectrum disease protectant for wheat and barley crops is realised with Ascra’s (prothioconazole + bixafen + fluopyram) approval in barley.

Ascra’s dual loading of two SDHIs offers a bit more punch than previous standard Siltra (prothioconazole + bixafen) and recent arrival Revystar (mefentrifluconazole + fluxapyroxad). In a range of 2021 and 2022 independent trials, it delivered mean yield responses over both.

That was reflected in on-farm trials with Bayer’s Forward Farmers group. Here mean yield responses above Siltra were 0.3 t/ha in winter barley comparisons and 0.2 t/ha in spring crop trials.

But there’s probably no better place than Ireland to test fungicides for wet weather diseases and Ascra has shown itself to be particularly active against wet weather disease threat number one, Rhynchosporium.

Teagasc researcher Dr Tom McCabe considers Rhynchosporium the major winter barley threat in Ireland and throughout much of the UK. A polycyclic disease, crops can be exposed to multiple infections and research has shown that this trash-borne disease can be spread by infected seed.

He puts this activity down to Ascra’s SDHI loading. He sees Ascra as a flexible option, suiting both key timings but is particularly useful as a winter barley T1 application due to the importance of protecting tillers. “Barley is a sink capacity crop so ear numbers are vital for yield. The T1 is all about tiller protection and retention. That SDHI loading is also giving an uplift to net blotch control, and with a good dose of prothioconazole it is effective against mildew too,” he notes.

SRUC Prof. Fiona Burnett agrees. SRUC trials have shown a slight slide in SDHI performance against net blotch resulting in higher rates being needed to maintain control. “Ascra’s high SDHI loading is bolstering activity,” she notes.

With SRUC spring barley trials she ponders whether the uplift in yield is partly down to physiological properties. “We know that plant stress is a factor in Ramularia infection, so any benefit in plant health is helpful. Much of the SDHI family have these additional properties, which we saw with strobs. Also, research has also shown that healthier plants photosynthesise more efficiently,” she adds.

She also welcomes the news that there has been no shift in the efficacy of prothioconazole, given that it is the cornerstone of most barley programmes. Ramularia control is still very dependent on azoles and she sees Ascra and Revystar as the two best options.

Dr McCabe is also reassured by the stability of prothioconazole and notes that Siltra is still performing well. He isn’t opposed to prothioconazole being used twice in barley disease control programmes, but urges that use remains at the two key timings. If a T0 is required to damp down winter barley disease he would prefer to see cyprodinil or spiroxamine applied.

One farmer who used Ascra for wheat and barley disease control programmes last season was Roger Hopley of Halfhead Farm, Stone, Staffs.

With strong yields and specific weight, LG Skyscraper has been his ‘go-to’ wheat. Mr Hopley likes to test agronomy tactics on-farm so he tried winter wheat KWS Dawsum, his aim to see if claims about high yields with good specific weight were justified and if its superior Septoria rating could help him keep on top of disease. He also had a look at winter barley LG Mountain too, comparing it against KWS Tardis.

A mixed enterprise, Mr Hopley doesn’t have the burden of black-grass so prefers to get winter wheat away early. Grass leys also help crops get off to a flying start given access to plenty of organic matter and also help nullify possible pest threats. Of course, as with most things there is often a downside, in this case, the risk of increased Septoria pressure.

He also looked at various fungicide programmes last season to evaluate effectiveness and returns. This added further proof that varietal resilience helps cap fungicide spend. Of the various Dawsum programmes he tried the best value came from a combination of Univoq (prothioconazole + fenpicoxamid) followed by Ascra.

The programme started with a T0 of Iodus (laminarin) followed by 1.5 l/ha of Univoq + Thiopron (sulphur) at the T1. This was supported with a 1.0 l/ha of Ascra at the T2 and the programme closed with an ear spray of tebuconazole. “We had a bit more rainfall here and the use of laminarin and sulphur helped check Septoria development and avoid higher fungicide rates. The programme wasn’t a significant outlay and it kept the crop clean, even with a September drilling date,” he notes.

Mountain might be described as the barley equivalent to Dawsum but without its disease resilience. It offers the same combination of high yield and specific weight but is a little dirty, rated just 5 for Rhynchosporium, net blotch and mildew.

With its susceptibility, Mr Hopley amended his two-spray Siltra programme with a switch to Ascra at the T2 and was pleased with all. “Mountain performed well last season so I’m sticking with it but it needs managing. A two-spray programme will suffice but it needs to be a robust one,” he concludes.