Growers will have to rethink the standard practice of overwintering carrots under straw, Agritec International managing director Peter Gresty told last month's Onion & Carrot conference.
"At the standard method of applying 40 Heston bales per acre (100/ha), you can do six acres a day, but -20 degsC is as much as that method can deal with," he said. "Once you have cell damage, there's no way back."
Aside from straw's practical limitations, there is also a major problem just around the corner, Gresty warned. "The dry spring has affected availability. Farmers may hold onto straw for bedding or to renutrify the soil.
"But there is also growing demand as a biomass fuel for power stations. The carrot industry needs 280,000 bales a season and we have to compete with all of these."
Continental growers, who are used to prolonged freezing conditions, rely more on overwinter storage, he said. "But you lose weight and finish and there is the risk of Sclerotinia."
Discussing alternatives, Gresty said: "Windrowing is difficult for the fresh market. Variety selection can help. Eskimo has frost tolerance and can be integrated into planting programmes."
While straw can be re-used, he explained: "You get a recovery rate of around 35 per cent but it's flattened so has lost insulation value."
More radical alternatives included reusable covers or harnessing geothermal heat, the availability of which coincides with carrot-growing areas, according to Gresty.
Applying salt was another option, but he urged more research into the viability of all these approaches.
Packaging review Retail opportunities
Different product formats could provide opportunities for carrot growers, Agritec International managing director Peter Gresty suggested.
"On the continent you see carrots individually wrapped in cellophane. In the USA, carrots are sold as snack foods and are even available from vending machines in schools."
Waitrose fresh produce technologist Caroline Mason said: "We are open-minded. Retailers won't always say no to grower's suggestions."