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Glyphosate risk awareness

1 August 2011

Seed potato growers should start building a glyphosate risk awareness programme now to help protect their crops from accidental but potentially costly contamination next summer.

As fields are selected and discussions on land rents begin, growers should make the most of these opportunities to assess the risk and talk with neighbours and landlords, says Mark Prentice, AHDB Potatoes head of seed and export.

The use of glyphosate has increased dramatically over the past 10 years as a pre-harvest desiccant for oilseed rape and wheat, he explains.

While that’s good news for those crops, it is potentially bad news for any seed potatoes nearby.

“Glyphosate is a non-selective weed-killer which is incredibly damaging to seed potatoes. Even at levels which cannot be detected it can cause horrendous problems with germination and emergence in the daughter crop.”

The most common cause of glyphosate contamination is spray drift, usually from a neighbouring oilseed rape or cereal receiving a pre-harvest spray.

Problems are most likely to occur when crops are grown on rented land, he adds. “The landlord may not be aware of the risks of glyphosate on a seed potato crop.

“So growers who are looking to rent land would be well advised to have a chat about these issues, as well as the more usual discussions about rent levels, to ensure that whoever sprays the neighbouring crops next summer is fully in the picture. These discussions will have to be followed up again in the summer, but it is important that every opportunity is taken to discuss this.”

Damage is rarely seen in the crop receiving the accidental dose. The problem arises in the daughter crop and may not be spotted until it has been planted, which can lead to very expensive legal claims, and certainly dissatisfied customers.

Typical spray drift effects can reduce emergence to just 25-30% of normal, says Mark. In severe cases it can be as low as 5%.

“Regardless of who causes the damage, the key thing to remember is that the seed grower needs to take positive action to reduce the risk,” he adds. “While the biggest risk of contamination occurs in July, it’s now that growers start to think about which fields they’ll be cropping and what’s surrounding them.”

AHDB Potatoes produced a leaflet and sticker set last year warning of the risks when spraying glyphosate near vulnerable seed potato crops and giving advice on safe application of the chemical to target crops.

“We still have plenty of these available for seed growers to hand out to farm businesses, sprayer operators and contractors,” says Mark.

The use of alternative, safer desiccants or no-spray zones in fields bordering susceptible seed crops are also worth exploring, he adds.

“Our approach is to tackle the root of the problem to reduce the risk, and we’d urge growers to do the same. A conversation or two now could save a lot of problems next summer.”

* Leaflet and stickers are available free from 024 7647 8772 or Sophie Lock on slock@potato.org.uk.

For more information go to Glyphosate Communications in the British Seed category.

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