The blighted progress of potatoes

Spuds may seem like a humble crop, but it takes a lot to bring them to your plate, writes Guy Singh-Watson.

I have loved growing potatoes since my first memories of helping my mother dig them in the garden. My first commercial crop was harvested with a tiny, gentle, tractor-drawn elevator digger. This sieved the soil to reveal the golden nuggets, which were dropped back on the ground to be hand-picked into sacks. Then came the Faun wrap-around harvester, which delivered the spuds into a bagger – and finally a trailed harvester, which deposited them into a trailer alongside. To speed up harvesting and improve the shape and ‘skin finish’ of potatoes, in the 90s it became the norm to pre-sieve, or ‘clod separate’, the soil before planting. 

But as machines got larger and harvesting got faster, the farm-gate price of potatoes fell. The minimum commercially viable acreage rose from two, to ten, to several hundred acres. Eventually, the specialist investment required drove small growers out of potato farming. I quit 30 years ago. The other casualty was the soil: beaten into a seed bed in spring, then sieved, driven over, sieved again, and (on non-organic farms) subjected to a barrage of synthetic fertilisers and pesticides.

Over all that time, a constant problem has been Phytophthora infestans: the humidity-loving, super-aggressive pathogen that causes potato blight. Its arrival in Ireland in 1845 was one of the triggers of the Great Famine, and blight has been with us ever since. Copper, in various formulations, can be a moderately effective fungicide. This used to be allowed under organic standards; however, copper is persistent in the environment and is non-selective, meaning that it also damages beneficial soil fungi. Over the last 20 years, copper has been progressively restricted, and finally banned as a fungicide on potatoes – leaving organic growers at the mercy of a disease that can wipe out a crop in a week. 

Our growers are trialling disease-resistant varieties, and planting potatoes further apart for better ventilation. Despite that, this wet summer has allowed blight to spread. To stop the dreaded disease from washing off the foliage and down to the tubers below in heavy rain, the crops have been mowed and then burnt. This seals the stems and kills any spores. Later this month, the potatoes’ skins will be set, and (weather permitting) they will be harvested at last. Savour them when they arrive; spuds may seem like a humble crop, but it takes a lot to bring them to your plate.

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