Potato growers have been warned to be on the look-out for rotting tubers appearing soon after stores are loaded. Localised heavy showers have led to small pockets of soft rots in some fields, which can cause problems in store.
"Generally the state of the crop looks good this year," notes Adrian Cunnington, operations manager at the British Potato Council's Sutton Bridge Experimental Unit. "But we have had some enquiries come through from growers calling the BPC storage advice line about rots, so there's cause for vigilance."
Soft rot, a seed-borne disease, is caused by Erwinia bacteria and shows itself as blackleg in the crop. Wet conditions tend to exacerbate the disease. The rotting tubers can be seen at harvest time as potatoes are loaded into trailers or boxes. This causes tuber break-down in localised pockets in the store, and can spread through an entire heap in a bulk store.
"A rogue temperature reading is often not a rogue probe, but an indication of trouble in store. But the first sign of trouble in a store is usually the smell. Any rotting tubers will need to be ventilated thoroughly and, if possible, cooled quickly. Storage life will inevitably be compromised by soft rot." advises Mr Cunnington.
Otherwise conditions have brought a very healthy-looking crop into most stores this season, he reports. "There was enough rain to keep some soil on the web, so bruising is not a problem. But it has been dry enough to ensure potatoes are fairly clean and generally sound for storage."
For fresh and pre-packed outlets, the emphasis now is to keep diseases, such as black dot, to a minimum. "Recent BPC research at Sutton Bridge has shown a fast temperature pull-down helps preserve skin finish and keeps black dot in check. Get the fans on, get the moisture off the crop and cool it down. Once it is at the desired temperature – 2.5 to 3.5°C– keep crop quality closely monitored so there are no surprises at unloading."
