Flexibility will be key for fogging strategies

With so many concerns about the quality of potatoes going into stores (Arable, 7 September), flexibility will be vital for fogging strategies this autumn.

Most CIPC sprout suppressants have a minimum 28-day interval between treatment and movement out of store but, with such variable quality, many growers fear stocks will not last this long, says John Purslow from Eagle Services, which treats around 100,000t of potatoes each season across western England.

“It’s going to be the worst storage season ever. I think there will be big problems with processing potatoes and we could see a lot of breakdown between now and Christmas.”

Store managers need to be extra vigilant for problem tubers and crops need to be dried, cooled, heeled and treated with a sprout suppressant as quickly as possible, he says. “We’ll probably use Gro-Stop 100 [chlorpropham] to start with, as this is the only one with a 48-hour interval, rather than 28 days for most others. The normal rate is 20-30ml per tonne for the first application, but you’ve got to assess the state of the store first. If the eyes are starting to open, we’ll probably go with the higher rate.”

Problem crops should be moved out of store quickly, he says. Better quality crops can then be treated with products that have a longer interval between treatment and movement. “Also make sure all your fans and probes are working properly,” he adds.


The combination of tuber blight and soft rot can have a greater impact than either disease alone, even in well managed stores, says the Central Science Laboratory’s John Elphinstone. At-risk crops – such as those from waterlogged spots or tramlines – should therefore be sampled prior to harvest, he says.

“This can be done by sampling and washing 300 tubers at random from the field and incubating them in a ‘hot box’ at 18-25C and observing disease development over one week. Alternatively, consider sending samples for laboratory analysis.”

  • Higher risk of storage problems
  • Test before harvest
  • Consider sprout suppressants with shorter intervals
  • Monitor stores closely
  • Maintain equipment