Po­ten­tial prob­lems for the potato

Han­nah Stephen­son re­ports on the ef­fect of weather on the spud

The Peterborough Evening Telegraph - - Advertisement Feature -

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.

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