Insight into crop agronomy challenges for June

1) Will there be more disease by T3? 

There’s still quite a while for rain to arrive before we reach ear wash spray timing in wheat crops, as this is written, which could change disease pressure quickly.  

If it is dry through flowering then crops will remain at low risk from diseases like Septoria and Fusarium, but warm, humid weather encourages brown rust. Conversely, wet weather will increase risk from Fusarium, with Septoria also a threat, especially if rates or less effective products were chosen at T2. 

Where disease pressure is higher, growers could have the option to use a SDHI-containing product, such as Aviator® Xpro® or Ascra® Xpro®, if they haven’t already used their two applications.  

Both will provide good control of rusts, Fusarium and Septoria and also give physiological benefits prolonging green leaf area retention and helping alleviate drought and heat stress.  

Where that isn’t an option or disease pressure is lower, combinations of prothioconazole, tebuconazole and strobilurins will be popular.  

2) Time desiccation sprays carefully for oilseed rape 

Spraying off oilseed rape with Roundup® is helpful for evening ripening in oilseed rape crops, but you need to be careful of the timing to avoid reducing yield or quality.  

To check whether crops are ready to be desiccated, pick at least 20 pods that are representative of the crop as a whole, and see whether at least two-thirds of the seeds in at least 75% of the pods have turned from green to brown. If they are, spray within four days and then leave for 14 days before harvesting.  

Where annual weeds are present use a rate of 1080g/ha of glyphosate. Increase to 1440g/ha if you’re targeting perennial weeds, alongside desiccation.  

Remember don’t spray off seed crops and if possible, spray in the morning for greater efficacy.  

3) Time to jump back into oilseed rape? 

Oilseed rape is the crop no one quite knows what to do with. Grown successfully, it’s still the best break crop option available, but growers who have lost whole crops to cabbage stem flea beetles, pigeons or slugs are understandably wary of growing it. 

But lower pressure from flea beetles in this season’s crop, which currently looks relatively decent, might tempt some to try again or continue.  

Broadly there seems to be two periods where establishment has the best chance of being successful – either drilling very early in late July or early August to get crops established before peak flea beetle migration, or delaying until after that peak and drilling in September.  

For the latter crops you’re looking for a variety with rapid autumn growth to get past both flea beetle damage and to achieve a good canopy before winter in the more limited time available.  

DK Extremus fits this profile as it has particularly rapid autumn growth, and is also very fast to start regrowing in the spring. It has RLM7-derived resistance to Phoma and strong light leaf spot resistance and provides consistent high yields.  

Like all DK varieties it also has pod shatter resistance and stands well.  

While DK Extremus can also be drilled earlier, DK Excentric is perhaps even more flexible with its drilling date. It has good autumn vigour but has a more prostrate, flatter growth habit. Disease resistance, including turnip yellows virus resistance, is strong, while yields match the Limagrain hybrids in independent trials by NIAB, Scottish Agronomy and trials contractor OAT.  

There are also a couple of candidate varieties to keep an eye out for if you visit variety trials this summer. CWH596, in particular, might be one to think about for the season after next when more seed will be available. It has triple Phoma resistance, both RLM7 and RLMS, plus turnip yellows virus resistance with rapid autumn growth and early spring regrowth traits – it is shaping up to be a good all-rounder.  

We also have a new clubroot resistant variety in DMH585, again with TuYV resistance in-built.  

4) Look out for Alternaria in potatoes 

Alternaria early blight spreads in alternating dry and wet conditions, which irrigating in dry weather could be creating. Usually, it’s less of problem except in certain very susceptible varieties, such as Markies, partly because the widespread use of mancozeb in late blight control programmes provides a level of early blight control.  

But with mancozeb in use up, there will likely be less being used this year, which could leave the door open for Alternaria.  

That could mean a specific fungicide with early blight activity will be needed in addition to the late blight programme. In EuroBlight trials, Caligula® scores highest for efficacy. It can be used at the recommended dose of 0.5 L/ha up to three times in a season but shouldn’t be applied in more than two consecutive sprays.  

5) Clarification of latest timing for Sivanto® Prime 

With sugar beet crops growing quite slowly in the dry weather, and aphids arriving sooner than Rothamsted forecast back in March, a three-spray insecticide programme may well be needed to control aphids that transmit virus yellows.  

That would mean all three of Insyst®, Teppeki® and Sivanto® Prime might be used in some order. The latest growth stage for application of Sivanto® Prime has been clarified as GS19 (nine or more true leaves) which allows for flexible application in the use period.  

In all crops, including potatoes, carrots and peas, there is also a latest date of application of 13 July to protect non-target insects and arthropods. 

6) Visit the Bayer Field Days event at Walpole 

We have a new venue for our Bayer Field Day in East Anglia this year – Pear Tree Farm in Walpole. Come to learn about new and existing wheat varieties in our extensive AHDB Recommended List and candidate variety plot trial, overlaid with different fungicide programmes. Delve deeper into fungicide performance with specific T1 and T2 trials and talk to Bayer experts about herbicide programmes for the autumn. 

We’d be delighted to see you on Thursday 3 July from 10am with the last tour at 3pm.  

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Ascra® Xpro® contains bixafen, fluopyram and prothioconazole. Aviator® Xpro® contains bixafen and prothioconazole. Caligula® contains fluopyram and prothioconazole. Insyst® contains acetamiprid. Roundup® contains glyphosate. Sivanto® Prime contains flupyradifurone. Teppeki® contains flonicamid.  Ascra®, Aviator®, Caligula®, Roundup®, Sivanto® 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