How to cope with dry or wet weather in crops this summer

1) Weather determines ear disease risk 

It seems likely there could be one of two scenarios you will be facing when it comes to ear wash sprays – either it has remained dry or the weather breaks, and almost inevitably, it’s turned quite wet.  

If it has remained dry and disease pressure is low, at least from wet weather diseases like Septoria and Fusarium, growers will be looking to save on fungicides where they can. But dry, warm weather can favour brown rust so that will need looking out for, remembering last year it was found in Yorkshire on susceptible varieties.  

If the weather does break, then a stronger T3 could be required. Talking to agronomists, it seems a decent amount are currently favouring Univoq® at T2, which would mean there is a slot available at T3 for a SDHI-containing fungicide, such as Aviator® Xpro® or Ascra® Xpro®. That would provide a little bit more activity on key diseases and some physiological benefits contributing to prolonged greening. 

Timing for ear sprays will depend on what you’re targeting. If Fusarium becomes the main threat, then it’s important to spray around early to mid-flowering, while if you’re topping up foliar disease control then you have a bit more flexibility as far as labels permit. 

2) Timing crucial for OSR desiccation 

Given the current weather pattern oilseed rape crops might ripen naturally without the need for glyphosate, but assuming the weather does change, and there’s some uneven maturing, using Roundup® will help create the uniform conditions for a successful harvest.  

Timing shouldn’t be judged by a calendar date of when you think you might want to harvest the crop – you need to adapt to the season. Right now, it looks like harvest could be early this year, although some rain could change that. Going too early with Roundup® not only will reduce yield and have a detrimental effect on oil content, it can also lead to a higher proportion of red seeds at harvest and potential rejections.  

To judge when to spray Roundup®, take a representative sample of around 20 pods from different areas of the field, and only spray if at least two-thirds of the seeds in at least 15 of the pods have turned from green to brown.  Using a Roundup® branded product typically will work more effectively, especially if sprayed in less-than-ideal conditions. Remember you can’t apply Roundup® to seed crops and there’s a 14-day harvest interval after spraying before combining. 

3) Look for autumn vigour in OSR varieties 

Oilseed rape in the north looks decent this year – it feels like it’s being a good growing year – which might tempt some people back in or to even increase area. The crop remains, if you can get it established, a good break crop, especially on heavier land where spring cropping is difficult, or where root crops are not part of the rotation.  

One of the keys to success is establishing into moisture, while gradually growers seem to be shifting into two distinct camps with drilling date – either very early in August or even late July to try to get the crop established before cabbage stem flea beetle populations build or waiting until after the peak migration and drilling in September.  

Good autumn vigour is an important trait for either drilling window. Generally, all the Bayer DEKALB® varieties have good autumn vigour and offer flexibility on drilling date.  

DK Excentric is a particularly flexible variety, which might suit someone looking to drill when moisture is available rather than in a specific window. It has good vigour, disease resistance including turnip yellows virus and grows with a more prostrate canopy. In independent trials, it’s yield performance matches Limagrain varieties, such as Ambassador and Aurelia, with a high oil content. Like virtually all DK varieties, it also comes with in-built pod shatter resistance.  

If you’re particularly looking to drill later, take a look at DK Extremus. It can also be drilled earlier, but has particularly rapid autumn growth that makes it a good variety for September drilling. It has good disease resistance, but one of its other strengths is that it gets away particularly quickly in the spring, which could be helpful in getting away from cabbage stem flea beetle larval attacks. It’s also shown good tolerance to Verticillium wilt in ADAS trials.  

4) Watch out for early blight 

Potatoes have been slow to emerge in the dry weather, although planting was done at pace in good conditions.  

While late blight will continue to take most focus, warm and humid weather, particularly if alternating between dry and wet conditions can also favour early blight development. Irrigating crops in dry weather can create such conditions. 

In the past, the wide use of mancozeb in late blight programmes has provided more than useful incidental control of early blight but, with it in use up this year, for some growers who didn’t purchase supplies for this season last year it won’t be an option.  

That could require the use of a specific product to control Alternaria, the fungus that causes early blight, particularly on susceptible varieties. Markies is particularly susceptible, but it can also cause problems on the likes of Hermes, Maris Piper, Maris Peer and Vivaldi.  

EuroBlight trials have found that Caligula® at 0.5 L/ha to be the strongest product on early blight. It doesn’t provide any control of late blight so needs to be used in addition – you can use up to three applications in the season, but no more than two consecutive sprays. 

5) Aphid control in sugar beet 

Like potatoes, sugar beet growth has been slowed by the lack of moisture, while the dry, warmish weather has also helped bring earlier flights of aphids into beet crops than originally forecast.  

That could well lead to all three foliar insecticide products being used in a programme to control aphids transmitting virus yellows this season.  

One of the products with label approval is new in Sivanto® Prime. There has been some confusion over the latest time of application with the product – in sugar beet it is GS 19, which is nine or more true leaves unfolded, which gives the flexibility to use through the danger period, including as a third spray. 

6) Test for resistance in grass weeds where appropriate 

Success or otherwise of grassweed control becomes apparent in June, making it a good time to look around the farm to review weed control programmes. Make a note of areas of poor control to help with strategies in the coming season, and also look for new or emerging threats – are patches of other weeds starting to appear or are they getting worse? Generally autumn residual herbicides appear to have worked well this season but if you have areas of unexplained poor control, it can also be worth thinking about doing a resistance test, especially for Italian ryegrass after the finding of resistance to glyphosate last season in a few isolated cases.     

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Ascra® Xpro® contains bixafen, fluopyram and prothioconazole. Aviator® Xpro® contains bixafen and prothioconazole. Caligula® contains fluopyram and prothioconazole. Roundup® contains glyphosate. Sivanto® Prime contains flupyradifurone. Univoq® contains fenpicoxamid and prothioconazole. Ascra®, Aviator®, Caligula®, DEKALB®, 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