Organic potato crops have been hit by a blight which means this year’s harvest may be only a quarter of the normal yield, organic farmers trade organisation Bionext has said.

Phytophthora, from the Greek for ‘the plant-destroyer’, is a type of mold which does particularly well in the warm and humid conditions which have been prevalent this summer. It spreads very rapidly and farmers who spot the condition must burn the affected plants.

Farmer Annewillem Maris from Dinteloord in Noord Brabant, who stands to lose some 30,000 kilos of potatoes, said the disease would be eradicated in a few years’ time when new, resistant varieties come in. ‘But for now I will lose a huge amount of money,’ he told broadcaster NOS.

But according to Bionext director Michaël Wilde, the switch to new resistant varieties can be a risk for farmers because demand remains low. ‘We can’t be sure consumers will suddenly start buying organic potatoes in greater numbers,’ he told the broadcaster.

There are 9,500 potato growers in the Netherlands but only 262 are organic, producing some 70,000 tonnes of potatoes in total.