I don’t know of any kitchen gardener who doesn’t relish the annual ritual of sowing and growing their own potatoes, from the special, muddy-fingered pleasure of burying the chitted seed deep into the cool, dark soil in early spring, to the cheering sight of those green shoots pushing their way up through the bare ground. There’s even the curiously enjoyable process of “earthing up” to look forward to, as well as the joy of harvesting and eating the crop come summer. Few things, I reckon, taste as good as a handful of freshly dug potatoes, lightly steamed and then tossed in butter and a dusting of sea salt. All of which brings me, with a reluctant sigh, to the only fly in the ointment of this otherwise hugely rewarding process, which is the threat of potato blight.
As every Irish schoolchild learns, the damaging fungal disease known as potato blight, or Phytopthora infestans, is capable of destroying an entire crop of potatoes with speed as well as with surprising stealth. As gardeners, we’ve had to devise various strategies to get around this problem. Many, for example, concentrate on growing “early” varieties such as ‘Orla’ that are less vulnerable to blight by virtue of the fact that they can be harvested within 12 or 14 weeks of being planted, before the disease has had a chance to strike. The downside of this particular tactic is having to forego the pleasure of growing and eating many of the delicious but much slower-growing maincrop varieties, such as ‘Kerr’s Pink’, ‘Pink Fir Apple’ or ‘Mayan Gold’.
Fungicides
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Other gardeners choose to protect their plants by spraying them with a fungicide. But while undoubtedly effective, even the copper-based fungicides traditionally approved for organic use are known to have an adverse affect on the health of humans and garden wildlife as well as that of the soil (classed as a heavy metal, copper does not break down in the ground but accumulates over time). A new, much more environmentally friendly alternative is Herfomyc, a concentrated herbal spray (available from Fruithill Farm) that stimulates the defence system of the potato plant, making it much more capable of resisting attack by potato blight. But just like traditional fungicides, it works only if used as a preventative rather than a cure.
For those of us who don’t have the time or the inclination to spray, another organically friendly option is to grow blight-resistant varieties such as ‘Sarpo Mira’, ‘Bionica’, or ‘Tibet’, which have an exceptionally strong genetic resistance to the disease. Relatively new to cultivation but few in number, these varieties are becoming increasingly popular, especially on allotment sites where the risk of the disease leapfrogging from plot to plot is of especial concern.
The different stories of why and how these particular varieties acquired their strong genetic resistance to the disease are interesting. In the case of the Sarpo range, it’s the result of a decades-long breeding programme that began in the Lake Balaton region of Hungary as part of an initiative by the then-Soviet empire, using South American and Mexican wild potato genes. That same breeding programme is carried on today by the Sarvari Research Trust in Wales.
The Dutch-bred ‘Bionica’ is also the product of a decades-long breeding programme that started when researchers from the Dutch university of Wageningen discovered wild varieties of potatoes growing in the Andes which, while not especially tasty or productive, showed exceptional resistance to blight. After much painstaking breeding work using these plants as genetic material alongside other tastier or more productive varieties, the result was ‘Bionica; not only did it exhibit exceptional blight resistance, but it produced very flavoursome floury tubers. As for the story of ‘Tibet’, this slow-to-crop but exceptionally blight-resistant, floury potato was supposedly discovered in a market stall in Nepal.
If you find these potatoes’ stories intriguing, you’ll be delighted to hear that the well-known organic gardener and author Klaus Laitenberger – as part of a group of professional gardeners and growers that includes Hans Wieland of the Organic Centre in Co Leitrim, the Kenmare-based grower Jan van Soest, and Alex Lavarde, head gardener at Mount Falcon Hotel in Co Mayo– is inviting Irish kitchen gardeners to participate in an informal, experimental potato-breeding trial this summer.
The group’s aim is to explore and encourage the possibility of new, exceptionally blight-resistant varieties of potatoes arising naturally from seed as the result of cross-pollination. With that in mind, each gardener will be growing anything from four to 14 different varieties of potato this year (some known for having a good degree of blight resistance, others for their exceptional flavour.productivity) and collecting their seed come autumn. By seed, I mean the potato plant’s true seed, as found inside the small, green, spherical berries that appear on the stems after flowering has finished (these look like miniature apples).
To encourage your potato plants to cross-pollinate and set seed, Laitenberger suggests growing the different varieties quite closely together in a square, with three seed potatoes per variety and three plants per sq m. He also suggests spraying them against blight. After harvesting the resulting seed in autumn and then cleaning and storing it somewhere cool and dry for the winter (much as you would tomato seed), you’ll need to sow it into seed trays the following spring before transplanting the baby potato plants into the garden in April. After that, it’s simply a case of measuring and recording the different plants’ varying ability to fight blight as well as, importantly, the tastiness of the resulting tubers. If Lady Luck is on your side, you might have a champion spud on your hands.
Klaus Laitenberger will launch his potato project in The Organic Centre in Co Leitrim tomorrow, Sunday 13th March, as part of its 20th Annual Potato Day celebrations. See theorganiccentre.ie
This week in the garden
Prune mophead hydrangeas (varieties of Hydrangea macrophylla), using a sharp secateurs to remove three or four of the thickest and oldest branches by cutting them right down to the ground. Then remove any remaining dead flowers by cutting the stems back to the first strong pair of leaf buds below each faded bloom. With very neglected or leggy plants, bite the bullet and cut all the stems back to about 40cm above ground. Finish off with a generous mulch of compost or manure around the base of the plant.
If you grow herbs such as chives in containers, now is a good time to start giving them a fortnightly, seaweed-based liquid feed to encourage lots of healthy, leafy growth.
