Disease control advice for crops in the north this May

1) Options for later drilled wheats at T1

Unless weather has intervened, I would expect earlier drilled and the bigger, more forward crops to have received T1 fungicide applications in late April, but some of the later drilled ones may still be waiting.

If the forecast rain hasn’t amounted to much, and disease pressure remains low on backward or later drilled wheats, then growers can think about using some of the older chemistry, which comes with a cheaper price tag.

In Bayer’s portfolio that would mean Ascra® Xpro®, which gives good broad spectrum disease control. Where yellow rust is more of a concern, for example in variety like Zyatt, you could look at a yellow rust specific product, such as Elatus® Era, while Vimoy® plus a partner is also exceptionally good on yellow rust. It’s broader spectrum than Elatus® Era, which means it also comes at a premium.

If Septoria pressure has increased with rain, then Vimoy® plus a partner or Ascra® Xpro® would also be good choices.

2) Working through an array of fungicide choices at T2

There’s no shortage of fungicide options for flag leaf sprays in wheat, but what you applied at T1, to some extent, could dictate what you might do at T2. For example, isoflucypram can only be applied once in the programme so if you’ve used it at T1, then it’s no longer an option. Similarly, fenpicoxamid (as in Univoq™️) and pydiflumetofen in Miravis® Plus have this restriction.

All three are options, assuming that restriction doesn’t apply, if the weather has become more conducive to Septoria in the run up to flag leaf applications. Miravis® Plus and Univoq® are both very good Septoria products but are not quite so good on other diseases, including rusts, so if other diseases are also an issue that’s where Vimoy® plus a partner could be an option.

Partners for Vimoy® include Jessico® One, Bayer’s version of fenpicoxamid, which is a very strong all-round product including against Septoria for high disease risk, and for high yield potential crops. Like Miravis® Plus and Univoq™️ it comes at a price to match its activity.

Where Septoria pressure is lower, products like Ascra® Xpro®, or Plaxium® if rust is higher risk could be alternatives with lower price tags.

3) Budget considerations for winter barley T2 sprays

While there is no doubt Miravis® Plus has looked excellent in trials as a T2 winter barley fungicide, its cost does mean you have to question whether it is good value as an awns emerging spray. If the weather has been such that there is much higher disease pressure than currently then there could be more justification technically, but it comes at a cost that I’m not sure farmers will want to spend, especially at current barley commodity prices.

Alternatives, such as Ascra® Xpro® and Siltra® Xpro® plus folpet, if you want to bolster Ramularia control are good options for broad spectrum foliar disease control at a lower cost point. Remember you can only apply Ascra® Xpro® once in a barley fungicide programme, unlike in wheat where you can use two applications.

If disease pressure is very low, you could also consider just applying a very cheap azole fungicide.

4) One or two sprays in spring barley?

Spring barley has been drilled in decent conditions and looks to have good yield potential, especially if the forecast rain in April arrived to push crops along.

It’s the old quandary of whether to use one or two fungicide sprays. If disease pressure is low, one might be enough, although timing is always a compromise, while wetter weather will have increased disease risk and justify two sprays.

Picking the right products at the right price is key. Both Ascra® Xpro® and Siltra® Xpro® could play a role, with the bixafen providing additional disease control over just using prothioconazole. If you go with a two-spray approach, apply the first timing at late tillering to early stem extension, with the follow up from flag leaf to awns emerging. For the one-spray approach apply a fungicide from flag leaf to awns emerging.

5) New insecticide to help with aphid control in potatoes

Potato growers will have a new option for controlling aphids that transmit viruses this season with the introduction of Sivanto® Prime.

Obviously particularly important for seed growers, it can also be used on ware crops. The active flupyradifurone has contact and translaminar activity. It’s best used earlier in the programme once thresholds are met as it has good knockdown activity and also a favourable beneficial insect profile to allow predator populations to build.

The product can also be used in sugar beet, peas, beans and carrots.

6) Plan blight programmes

While the dominant blight strain in the UK remains EU_36, a couple of cases of the EU_46 strain, which has caused problems in northern Europe, were found in the UK last season. In Europe this strain shows resistance to products with the OSBPI mode of action, like Zorvec®.

That means alternating and mixing modes of action, while making sure the maximum number of applications of particular groups isn’t exceeded is important in managing both blight efficacy and resistance risk.

With mancozeb no longer available for purchase, existing products are likely to come under greater pressure where growers were unable to buy enough in advance for the coming use up period this season.

Infinito® has a particularly useful place in programmes – neither active propamocarb or fluopicolide are affected by the resistant blight strains, and it provides good efficacy against both foliar and tuber blight, making it useful at all stages of the programme.

It can be used four times in a season. Historically, growers might have saved its use to the end of the season as there were fewer alternatives for tuber blight control, but with the need to alternate modes of action it’s worth considering using it earlier in the season as well, although I would still save at least one application for the end of season period.

7) Good looking oilseed rape crops might need double protection

Oilseed rape crops look better than they have done in previous years in Yorkshire, albeit with a few patchier ones where pigeons have got them.

These might be more varied in growth stages, which can make deciding whether you need a second flowering fungicide spray a trickier decision. Even crops are easier to manage because they are obviously flowering at the same time.

As with barley, the oilseed rape commodity price might influence decision making on second fungicides, but technically a first flowering spray will give around three weeks protection from Sclerotinia, as well as suppressing light leaf spot.

If crops continue flowering much beyond three weeks, it’s worth considering whether to follow up with more protection. That doesn’t need to be a very expensive spray – Aviator® Xpro® will provide protection as well as giving a greening benefit over but if you’ve used an SDHI fungicide as the first flowering spray, you could also consider using Proline® as the follow up.

8) Visit our Cawood Field Day on 5 June 2025

Our regular field day at Stockbridge Technology Centre at Cawood, Selby will be held on 5 June 2025. Starting at 10am, with last tours at 3pm, highlights include wheat variety plots from the current AHDB Recommended List and new candidates, disease control trials focusing on Septoria, yellow rust and brown rust control, plus the ever-popular and informative weed screen.

And if that wasn’t enough, food and refreshments will also be available. Hope to see you there!

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Aviator® Xpro® contains bixafen and prothioconazole. Ascra® Xpro® contains bixafen, fluopyram and prothioconazole. Elatus® Era contains benzovindiflupyr and prothioconazole. Infinito® contains fluopicolide and propamocarb. Jessico® One contains fenpicoxamid. Miravis® Plus contains pydiflumetofen. Plaxium® contains isoflucypram, fluopyram and prothioconazole. Proline® contains prothioconazole. Siltra® Xpro® contains bixafen and prothioconazole. Sivanto® Prime contains flupyradifurone. Univoq^TM contains fenpicoxamid and prothioconazole. Vimoy® contains isoflucypram. Zorvec® contains oxathiapiprolin.

Aviator®, Ascra®, Infinito®, Jessico®, Plaxium®, Proline®, Siltra®, Sivanto®, Vimoy® and Xpro® are registered Trademarks of Bayer. All other brand names used are Trademarks of other manufacturers in which proprietary rights may exist. Use plant protection products safely. Always read the label and product information before use. Pay attention to the risk indications and follow the safety precautions on the label. For further information, including contact details, visit www.cropscience.bayer.co.uk or call 0808 1969522. © Bayer CropScience Limited 2025