Potential problems for the potato

Hannah Stephenson reports on the effect of weather on the spud

The wet weather over the past couple of years has prompted reports of poor harvests, and claims that the nutrients the rain has washed away will affect our home- grown produce. Among the crops worst hit in vegetable patches across the country is the humble spud, a staple of the British menu for centuries, whether boiled, mashed or chipped.

A n d wh i l e g a r d e n e r s throughout the UK will be celebrating National Potato Day with events up until the end of the month, experts are now warning that gardeners must start to grow a mixture of varieties to stem the loss of crops to late blight.

Affected plants develop brown spots, especially around theedgesoftheleaves, thestems turn brown and potatoes develop scabby cankers that lead to brownpatchesinsidethetubers which soon rot.

BobSherman, chiefhorticultural officer of charity Garden Organic, warns: “Rare types of potatoesareunderthreat. There isn’t muchthattheamateurgardenercandotoprotectpotatoes from blight.

“Late blight is a very rapidly evolving organism. It’s not quite a fungus, but acts like one. Spores flow in the air, usually coming from old tubers left in the soil which haven’t been harvested from the previous year because they’ve been missed.

“Most of the old varieties of potato are highly susceptible andevenonesthatwerethought to be resistant have succumbed to new strains of the disease. We used to think that ‘ Cara’ was blight resistant, but it isn’t any more. Awholerange of interesting textures and flavours from old varieties are under threat.”

Incessant wet weather causes both disease and physical problems with potatoes.

“Whenpotatoesgettoomuch moisture, you might get one or twohugepotatoesunderthesoil instead of a nice little clump of medium- sized tubers. Thehuge ones might be hollow inside or just not very tasty. Dry weather tends to enhance flavour, but wet weather reduces it.”

Somegardenershaveturned to resistant varieties which is keeping blight at bay.

Otheradviceistoharvestearlier, or grow spuds in pots and bring them under cover later in the year. Blight usually strikes from July onwards, depending on the weather and which part of the country you live in.

Of course you can enrich your soil with plenty of organic matter, but if the weather’s damp, it won’t make any difference to blight, because the spores are carried in the air.

Covering the plants with tunnels or cloches may also not makeadifferencebecausepotatoes need good air flow. If your tunnels are plastic, blight will thrive in the humidity. If you have a good- sized greenhouse, you may have more luck if you constantly remove the leaves showing signs of blight.

If the blight is widespread, take all the leaves off, which will mean a smaller crop, but at least you’ll have a crop. However, if you do remove leaves, don’t lift any potatoes for at least two weeks afterwards, because the spores will still beonthesurface of the soil, and if they come into contact with a tuber, they will affect it.