Pesticides regulations in the UK could be even stricter post-Brexit, members of the seed industry were told at the AHDB Potatoes Conference. Ewan Pate reports from Scotland.
Desiccating seed potato crops has always been challenging as regards timing and efficacy. The loss of herbicide diquat after the 2019 season will do nothing to make it easier.
Norfolk seed potato producer Tony Bambridge raised the topic at the AHDB Potatoes conference at St Andrews. Head of SASA (Science and Advice for Scottish Agriculture) Gerry Saddler acknowledged the problem but said there would probably be little scope for diquat to be retained post- Brexit.
“Europe will always be a main partner so it is very likely that we will have to abide by EU rules if we want to trade. That will mean that the chances of using diquat will be incredibly limited,” he said.
Rob Clayton, director of strategy at AHDB Potatoes said he would support a derogation for using diquat as a desiccant, particularly for seed crops, but he warned that pesticide regulation in the UK post-Brexit could be even tougher than in the EU.
“There are some diquat replacements and we will be trialing them on the SPot Farms next year,” he said.
This however brought a retort from Scottish Agronomy’s Eric Anderson : “There is quite a difference between demonstration plots at SPot Farms and trials. Which is it to be?” he asked. Mr Clayton replied: “ I know we that need both robust trials and demonstrations.”
The loss of diquat also featured in a blackleg workshop, with Professor Ian Toth of James Hutton Institute saying that it was the best material for killing bacteria in a blackleg-infected crop.
“It is simply a case of faster haulm death equaling less pectobacterium. Spotlight is the next best material, it leaves more pectobacterium but there is noticeably better stolon separation which is an advantage. Gozai is effective but on senescing plants only,” said Prof Toth.
He added that the best results he had seen commercially were in North Angus, where a grower had pre-treated a crop with one litre per hectare of Spotlight in 400 litres of water followed by flailing. He had then applied Gozai followed by a final application of Spotlight at 0.6 litres per hectare.