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Emily Harrod

East Anglia: Helpful advice for May’s busy agronomy period

Article overview

Emily Harrod runs through some advice for key agronomy decisions in May

Crop Progress

The variation in drilling dates and crop potential has taken quite a bit of managing, and even in mid-April I was still taking phone calls about herbicides rather than fungicides, which probably shows the range of crops and growth stages growers are dealing with.

It wasn’t hard to find Septoria or yellow rust in susceptible varieties around the T1 timing in late April, which suggests disease pressure at the timing was high. Timing sprays correctly was also tricky, and there may well have been some T1s applied a little early, which might require a T1.5 if the cold weather continues to slow growth until flag leaf sprays.

Emily’s agronomy tips for May

Finish off late T1s in wheat

An immediate priority in wheat crops in early May will be finishing off any remaining T1 applications.

Just because these crops were late drilled and / or crop potential is relatively low doesn’t mean cutting completely back on fungicide programmes, as these crops will still be at risk from disease.

Either Ascra® (bixafen + fluopyram + prothioconazole) or Vimoy® (isoflucypram) + Proline® (prothioconazole) could be suitable for this timing offering broad spectrum disease control. Which one you select will depend on variety disease risk rather than crop potential.

This will also help reduce pressure on T2s – cutting back too much at T1 with the high disease pressure could easily see difficult situations at T2 this year.

Assess disease risk at T2

With around a month before T2 sprays will be due when writing this, it’s impossible to know what the disease risk will be at that point.

If the weather continues to be showery through May, probably with warmer temperatures, that will increase the risk from Septoria, while yellow rust and brown rust could also threaten.

That will likely mean using a robust programme. This year, if you haven’t used Vimoy® or an Inatreq® (fenpicoxamid) containing product at T1, could mean using Vimoy® + Jessico® One (fenpicoxamid) at T2, which are two of the best Septoria actives available, along with the newly approved adepidyn® from Syngenta.

I think using different modes of action and actives at T1 and T2, where possible, is important, and with the new fungicides available this season that is easier than in recent seasons.

Other possibilities include mefentrifluconazole products and Univoq® (fenpicoxamid + prothioconazole).

Where crops are clean because of good T1 timing and product choice, and / or if disease pressure has dropped off because there’s been little rain between T1 and T2, then Ascra® at 1.2 L/ha is another possibility, as well as Vimoy® + Proline® (prothioconazole).

Apply awns emerging sprays in winter barley

Similarly, to wheat T1s there will likely be a few remaining winter barley awns emerging sprays left to do in early May.

Ramularia, along with the usual foliar diseases like net blotch, Rhynchosporium and brown rust, will be the main concern. Ramularia seems to be exacerbated by crop stress, which could make it higher risk this season. Low nitrogen, scorch and exposure to light also increases risk, as does the process of flowering as plants mobilise nutrient resources away from the leaves.

It’s easy to confuse with abiotic spotting but the key difference is Ramularia leaf spotting is on both sides of the leaf, rather than just one side with physiological leaf spotting.

With resistant strains of Ramularia widespread it is important to use as many different modes of action as possible, with Ascra® (bixafen + fluopyram + prothioconazole) or Revystar® (mefentrifluconazole + fluxapyroxad) plus possibly folpet the main choices at T2 for Ramularia, while Siltra® (bixafen + prothioconazole) is also an option especially where disease pressure is lower and Ascra® has already been used at T1.

One or two sprays for spring barley disease control?

I would imagine most growers are thinking about just one fungicide spray for spring barley this season. While I understand that view, especially in late drilled crops with relatively poor potential, it might not always be advisable especially where trying to obtain highest quality grain for what is likely to be a competitive malting spring barley market.

The case for two sprays is also there when you expect there to be a Ramularia risk – the timing for one spray will likely compromise either control of early foliar diseases or Ramularia, so I wouldn’t completely throw out the second spray option.

If you do plan on one-spray Ascra® at 0.9 L/ha possibly plus folpet would be a good robust treatment.

Also consider micronutrition requirements – with crops not having been drilled in the best conditions, it will be even more important to make sure the plant is receiving the right micronutrients to improve plant health in conjunction with fungicide treatments.

Prolonged oilseed rape flowering requires attention

It’s been a prolonged oilseed rape flowering period this spring and as I write it doesn’t look like ending anytime soon.

That could mean a second flowering spray will be required – most fungicides give about three weeks protection against Sclerotinia, and the showery weather will have been conducive to increased risk, albeit with cooler temperatures being a confounding factor.

If you do think a second spray is worthwhile from a resistant management point of view using a straight azole at flowering is not going to be robust enough. It will be fine though if you used a more robust product as a first spray. Other options include Filan® (boscalid).

Where straight prothioconazole was used as the first spray, another option could be Aviator® (bixafen + prothioconazole), where the addition of the SDHI will help bolster control.

Take care with beet herbicide applications

Sugar beet drilling only started in earnest in mid-April. Pre-emergence herbicides have been more popular this year where the available soil moisture will have helped with efficacy.

That should help take some pressure off very early post-emergence contact treatments, such as with Betanal® Tandem® (phenmedipham + ethofumesate), which will be a good cornerstone of the programme.

Applying contacts to slightly bigger beet should reduce crop damage risk, which will be important in reducing any growth check to the crop in the race to get to the 12TL stage where it becomes more tolerant of virus yellows.

Even so, in hopefully warmer weather in May be careful when using contacts especially with mineral oils. With Betanal® Tandem® we advise not adding in a methylated rapeseed or vegetable oil if forecast temperatures are over 21C, with a sliding scale for the amount of oil to use when temperatures are below that.

Where Conviso® Smart herbicide tolerant beet are being grown also have a look at our Stewardship guide, which helps protect the future use of the system.

Be prepared for fast emerging potato crops

Potato planting in late April and into May will likely be into warming seedbeds with potato seed that has broken dormancy, which means emergence could be much quicker than earlier planted crops.

Where using herbicides that means being extra careful with timing. If you’re planning to use Roundup® (glyphosate), which might be required with the difficulty in applying pre-planting sprays, timeliness needs to be spot on as you need to be very sure that crops are nowhere near emerging. If in doubt, it is best not to apply it.

Similarly with Emerger® (aclonifen) pre-emergence sprays, our guidance is that it should be applied at least seven days before crop emergence to avoid crop damage. Emerger® will provide good control of a wide spectrum of broadleaf weeds and help also against grassweeds.

Artist® (flufenacet + metribuzin) makes a good partner where grassweed pressure is higher, while Sencorex® Flow (metribuzin) can be used to fill in and improve broadleaf weed control.

Both Artist® and Sencorex® Flow can only be used on metribuzin tolerant varieties, while also being mindful of soil types. If you’re unsure about your variety, check either on our website, refer to breeder’s technical sheets or get in touch.


Ascra contains bixafen + prothioconazole + fluopyram. Vimoy containts isoflucypram. Proline contains prothioconazole. Jessico One containts fenpicoxamid. Adepidyn contains pydiflumetofen. Univoq contains fenpicoxamid + prothioconazole. Revystar contains mefentrifluconazole + fluxapyroxad. Siltra contains bixafen + prothioconazole. Filan contains boscalid. Aviator contains bixafen + prothioconazole. Betanal Tandem contains phenmedipham + ethofumesate. Conviso One contains foramsulfuron + thiencarbazone. Roundup contains glyphosate. Emerger contains aclonifen. Artist contains flufenacet + metribuzin. Sencorex Flow contains metribuzin. Ascra, Vimoy, Proline, Jessico One, Siltra, Aviator, Betanal Tandem, Conviso One, Roundup, Emerger, Artist and Sencorex Flow 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 or call 0808 1969522

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