Ben Lowe is an Agrovista agronomist based on the East Coast of Scotland, supporting customers from Dundee up to South Aberdeenshire. With a specialism in row crops, in this article he provides an update on potato crop herbicides.

Although we’re all a little tired of talking about the weather, the main thing I’ve been keeping my eye on is soil moisture, because it’s key in ensuring we get the best out of residual chemistry.

“To make sure pre-emergence herbicides work most efficiently, moisture on the ridges is needed. And by moisture, we don’t want too much either, because this will wash away the active ingredient, or move it into the crop and cause damage.

“Despite the driest May on record, it seems that pre-em sprays have been successful and worked reasonably well for most of the farms that I advise for. Crops are beginning to emerge in most cases and monitoring the success of those pre-em sprays as well as pest numbers will be important.

“We can top-up with follow up herbicides, but really we want our pre-em sprays to be successful. Ultimately, if growers have grass weeds in their crop now, it’s a red flag for harvest. Grasses cause clumping in the bed, meaning the soil needs more agitation which impinges on harvest practicalities. It also of course impacts seed return for following rotations.

“One of the best ways we can overcome weeds naturally is by getting the crop to canopy closure as soon as possible. Blocking weeds’ access to sunlight through a vigorous crop will suppress them before we even think about chemicals.

“At the moment, crops are well ahead of where we have been for the past five years. We set a target of reaching crop canopy by the longest day of the year, maximising daylight for photosynthesis. This year, achieving that target IT be an issue.

“Using forecasting and tools such as weather stations and soil moisture probes help me to plan for my customers, especially during the Covid-19 restrictions. For those with their own weather stations, this gives site-specific remotely-accessible data, which provides invaluable insight into the potato plant’s development. If this data is field-specific, even better due to the huge variances we experience in rainfall.

“Organisation will be key as we continue to work together to overcome the challenges of Covid-19. Keeping in regular contact with agronomists, albeit at distance, will help to mitigate supply chain issues.

“And without diquat, it’s likely the whole weed management programme will need to be adjusted for many.”