‘Zapping’ brown rot away

A LINCS POTATO grower under irrigation restrictions because of brown rot disease has used an ultraviolet water filtration unit to overcome the problem. As well as being cheaper than chemicals, it has found favour with buyers and requires little maintenance.

Until recently, chemical treatment was the only option for growers banned from irrigating where abstraction sources are designated brown rot contaminated, says producer Michael Scott, the UK”s first potato grower to use the UV system.

He bought two UV units last year for separate blocks of drip-irrigated land at EA Drings farm near Boston. Supplier was Wroot Water Systems of Doncaster, S Yorks.

The one-off £16,000 investment for both units was a better prospect than an annual bill of a similar amount for chemical treatment, reckons Mr Scott.

Buyer confidence was also an issue. “Food buyers are increasingly turning against chemical treatments of any kind. Chemicals for treating brown rot in watercourses have been approved, but I was keen to look at alternatives.”

Each unit can handle enough water for 40ha (100 acres) of potatoes. About 80ha (200 acres) of packing potatoes are grown in total, mainly for supermarkets like Marks & Spencer.

Being the first producer in the country to use the UV system in this way meant there were some minor technical difficulties at first, admits Mr Scott. But once the units were up and running, maintenance was minimal. The system was monitored by DEFRA, and officials gave full approval, after testing showed 100% kill of harmful bacteria.

“Chemical treatments cause corrosion in irrigation pipelines, and a lot of labour is needed to keep the system topped up,” says Mr Scott. “By comparison, the UV system is fairly straightforward to run. I am expecting to get several seasons out of each unit, because the design is so simple, although the UV bulbs do need to be changed every so often.

“DEFRA has deemed the system reliable, because it automatically shuts down if the machinery is not working properly.”

Although brown rot has been found in the upper reaches of the River Witham, it has not been detected in the section of the river where the farm draws water. “This has all created a lot of additional cost – just because the farm happens to be in the wrong place. But it is something we just have to deal with,” Mr Scott concludes.