The answer to potato blight (From The Oxford Times)

The answer to potato blight

6:40am Thursday 27th August 2009 in Leisure By Val Bourne

I get a lot of stick for being a green gardener — one who has never used a chemical preparation in a garden. Some writers greet me with ‘spray it’ rather than hello for instance. Some gardeners think I’m conning the public: that my garden must be ravaged by hordes of pests. It’s a very difficult to explain that I have a robust ecosystem and that I get fewer problems — not more.

One of the green measures I’ve taken for many years is to grow most of my own potatoes because commercial crops can be sprayed every three days during wet summers to prevent potato blight. This fungal disease hits most gardens and allotments in mid-August in spells of damp, humid weather. The first signs are black lesions followed by wilting foliage and then the disease goes underground and blackens the tubers making the crop inedible. A commercial crop is sprayed an average of 16 times to prevent this and chemical residues must get left in the ground and washed into water sources.

Potato Blight is an old chestnut. It caused The Great Famine of 1845 when the heavy yielding variety called ‘Lumper’ was ravaged but, despite this, potatoes still feed the world. They apparently provide the greatest crop of any vegetable or cereal per acre. Russia funded new research into blight-resistant potatoes in the 1950s and 1960s. The work was carried out in Hungary using potato species originally collected from South America in the early years of the 20th century. These varieties, housed in Russian Botanic Gardens, which are often no longer found in the wild, provided a unique resource of resistant breeding material.

When the Soviet bloc broke up, the chief scientist hid his disease-resistant tubers under his bed and carried on breeding independently in secret. The potatoes came to the West’s attention when Scottish breeders noticed an unaffected crop amid a blight-ridden trial. The foliage was tall and entirely healthy. After careful negotiation, the research project moved to Bangor, in Wales, and blight-resistant potatoes with the Sarpo prefix began to appear about five years ago.

Gardeners have embraced the two varieties of Sarpo potatoes available. ‘ Sarpo Axona’ is a red-skinned potato with creamy flesh and ‘Sarpo Mira’ is similar in appearance but more floury. They both sell well (from Thompson & Morgan) and there are four new ‘Sarpo’ varieties on the horizon which may well be available by 2012. ‘Blue Danube’ is also one of their varieties, but it doesn’t have the Sarpo prefix. The foliage can suffer slightly from blight, although the floury tubers are completely resistant.

Sadly, commercial growers have shunned Sarpo varieties so far. But the writing is on the wall. Chemical use is being restricted by legislation in horticulture and gardening and the Sarpo breeding program offers the only future solution.