The twin pressures of losing standard herbicides and the difficulty of registering new ones will make conventional weed control a challenge for vegetable growers in the coming years, consultant Cathy Knott said at the SCEPTRE vegetable weed-control open day last week.
"Alternatives are needed by the industry - without them, vegetable growing could become uneconomic," she told Grower.
"But it's more and more difficult to find new ones. For a while there wasn't any new chemistry coming through - the companies weren't interested in bringing them into Europe for minor crops. It's difficult enough for them to get chemicals into Europe for their major markets."
Knott oversees trials of candidate herbicides for use on field vegetables at Elsom's trial grounds near Spalding, Lincolnshire, which were open to industry visitors for the day.
This year's trial compares the effects of three unnamed conventional herbicides that are already authorised at EU level, used preand post-emergence on 15 field vegetable crops as well as volunteer potatoes at standard, halfand double-dose rates, requiring a total of 768 plots.
One conclusion to be drawn is that newer herbicides generally have a narrowed weed spectrum, so would have to be used in combination, she said. One candidate, an alternative to Linuron on carrots, could be available as soon as next year.
"Linuron is going to go - it's up for review in 2016 and has already been lost in Germany and Denmark," added Knott. "We are more than likely to lose Bromoxynil for salad onions and leeks. We have already lost a lot of controls and if we lose Stomp (pendimethalin) too then we might as well pack up."
Funding programme Fresh-produce studies
SCEPTRE (Sustainable Crop & Environment Protection - Targeted Research for Edibles) forms part of Defra's now closed HortLink programme to fund applied fresh-produce research.
It is currently in year three of four, although the tests SCEPTRE continue a programme of candidate herbicide trials that began in 2004 and transferred to the Elsom's site in 2010.