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Seed treatment gap could leave some crops uneconomic – The Vegetable Farmer – Andy Richardson

A change in approval conditions for fungicide seed treatments containing metalaxyl-M will leave a range of drilled field vegetables ...

Including onions, pulses and some baby-leaf and herb crops – without effective pre-establishment protection against damping-off, downy mildews and other diseases caused by oomycete pathogens.

Metalaxyl-M was reauthorised as an active substance for a further 15 years in 2020 but with a new restriction, effective from June 30 this year in Britain, that seed treated with products containing it could not be sown outdoors.

“The only remaining use for metalaxyl-M seed treatment will be an amended authorisation for Apron XL for selected brassica crops,” said authorisation-holder Syngenta. “That use will be restricted to seed sown and raised under fully protected conditions, with a minimum of 21 days from sowing to planting out. There are limited alternative seed treatments available for vegetable growers of some crops, for example Maxim 480S (fludioxonil).”

The company said the restriction had been imposed from June 1 in Northern Ireland, just a few days after CRD had issued its notification and after many growers there had already made cropping decisions.

“While it’s good that it’s still available for brassica transplant production, where pythium can be a real problem for plant raisers, its loss is a real issue for drilled crops,” Allium & Brassica Agronomy managing director Andy Richardson told The Vegetable Farmer.

He said the company had run two drilled onion trials using untreated seed that had resulted in one complete crop failure and another where establishment was just 35 per sq m compared with the 45 (from 60 per sq m drilled) that’s accepted as the minimum for a viable crop. “That’s just not economic at current prices,” he said.

“There are no alternatives and the decision [to ban use of treated seed outdoors] doesn’t make sense. I don’t see any evidence that treated seed is being eaten by birds and mammals; if it was growers would be losing crops to them. These were well-targeted treatments using relatively small amounts of product.”

Mr Richardson added: “With no new products coming through its hugely frustrating. There doesn’t seem to be any sense coming out of CRD and growers are getting desperate.”

Wakil XL was the metalaxyl-M treatment used on pea and bean seeds to manage downy mildew and other diseases. PGRO pathologist Lea Herold said: “It looks likely that we will not have any fungicidal seed treatment available for peas for next season. In vining peas, Revus (mandipropamid) is approved for downy mildew control but no foliar fungicides are approved for controlling the disease in combining peas.”

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