Seek safety from rot risk

The British Potato Council (BPC) is urging growers to remain vigilant in the drive to reduce the risk of serious disease threats to UK crops.

Ware growers should keep a close eye on crops for unusual symptoms, take hygiene measures on farm to protect against diseases such as Dickeya dianthicola and above all ask their supplier for Safe Haven seed, says BPC seed and export manager Iain Dykes.

"We're fairly sure Dickeya is far more widespread than the 40 cases reported to date," he reports. "But that's only one of several disease threats growers face. The best protection for the industry from devastating diseases such as ring rot and brown rot is to source seed produced under the Safe Haven Certification Scheme. Around half of the British seed area is now in the scheme, and I'd strongly encourage non-assured seed growers to join."

D. dianthicola, one of the Erwinia chrysanthemi complex of bacteria, can cause tuber rots and up to 100% crop loss, this disease is already having financial implications for the industry but the potential impact of the disease becoming widespread could be much greater. Quarantine diseases like ring rot could have an even greater impact with conservative estimates put at around £10.7million per year and this doesn't take into account the cost of disposals and clean-up to individual businesses.

"There is no insurance or compensation available in Britain for ring rot, and a serious outbreak would devastate the company involved and have serious consequences for the industry," points out Mr Dykes. "That's why growers should think carefully about where their seed comes from."

When growers delay ordering their seed, he notes, it can leave them with limited choice. "Place your seed order now, and source Safe Haven seed wherever possible."

Only those seed growers who can demonstrate the highest hygiene standards, and can show that they have not grown seed from imported stocks, can join the Safe Haven scheme. This policy of exclusion offers the industry the best guarantee there is of ring rot-free seed, and provides the best protection against D. dianthicola and other serious diseases.

"For the vast majority of seed growers in the UK, these measures will be normal practice. So it makes sense to join the Safe Haven scheme and make the industry's protection against serious disease more robust."

"We need to know how widespread D. dianthicola is in GB crops. It is hard to diagnose, so if you spot unusual wilting in your crop, send samples in to get it diagnosed."

There is no treatment for the seed-borne disease, adds Mr Dykes. "If you've any doubt over your seed, it's safest to have a diagnostic test done to detect latent infections, pathogen identity and pathogen levels."

BPC advice to growers includes checking varietal susceptibility, removing rots and cleaning the grader prior to use. To reduce the risk of rots developing in store, harvest early, minimise damage to tubers and ventilate using dry air. Grower should avoid poorly-drained fields and short rotations, and try to minimise de-sprouting at planting.

More research has been commissioned by the BPC to improve understanding of D. dianthicola and other Dickeya species in British stocks and imported seed. The study, which will be carried out by John Elphinstone of Central Science Laboratory, will provide the first detailed information on the distribution in Britain and the rest of Europe.