HERITAGE varieties of potato have been the subject of recent 'field lab' trials in Scotland and England aimed at finding alternative techniques to manage blight.

Organised by the Innovative Farmers network, the trials found that all heritage varieties, including some of the newer breeds, performed well for yield and blight resistance. A taste test also found that all of them tasted good when cooked as chips and mash.

Soil Association head of horticulture Ben Raskin said: “Late blight is likely to challenge all potato growers as conventional chemistry becomes more restricted. There are some systems and management strategies that can help, for instance agroforestry planting can slow the spread of the disease across a field, and plant tonics and stimulant can help boost the crops natural resistance.

"However these are limited and the reality is that most certified organic growers either top the crop – using a burner or a flail mower – when late blight arrives, or use copper to control its onset and spread.

“By raising awareness of different varieties amongst growers and consumers in this Innovative Farmers field lab we hope to find more natural answers to such a common and devastating problem as blight.”

The most dangerous current strain of blight is the 13-A2 and traditionally resistant varieties such as Cara and Lady Balfour are now no longer able to withstand the disease. Breeding by the Savari trust and Agrico has helped increase the number of blight resistant varieties available, but not all match the appearance and taste specifications favoured by the majority of the market.

The heritage variety trials involved a small number of growers across the UK – two in Gloucestershire and one in Scotland on the Black Isle. The group tested the performance of up to 11 varieties of potato against blight, and then performed a taste test to help convince consumers and retailers that different varieties can also be good to eat.

Daniel Ross of Fearniewell Farm said: “I wanted to find out what grows well in the conditions here – our soil is 3.1 or 3.2 so slightly marginal compared to most potato growing conditions, so the plants might not perform as expected. The only disease we have here so far is blight and so growing blight resistant varieties is something of interest to me. We don’t spray with copper as it has detrimental side effects, so proper resistance is crucial, otherwise a lot of time is spent removing and destroying diseased tissue, to help an adequate yield be reached before dehaulming.

“Customers can be particular about potato variety and characteristics, so I have grown a range to see what’s popular with them in the past, but having found a high performing – yield, flavour, disease resistance – and properly blight resistant variety I’ll be growing only one main crop variety this year.”

Full trial results are available on the Innovative Farmers website.