Features
What Do Organic Growers Do About Blight?
Blight is the chief cause of concern for potato growers. Warm wet summers favour the spread of the disease. The first signs of blight are brown patches on the leaves of plants which eventually turn black and destroy them. The spores then fall onto the soil where they are washed down by the rain to infect the tubers. On tubers, brown spots can be seen beneath the skin where they quickly spread and destroy them.
Plant Early
As blight is often not a problem till mid-July, gardeners in milder parts of the country can sometimes grow an early crop which they can harvest before the disease arrives. In most other parts of the country the only way to achieve this would be by growing a crop under protection in a polytunnel or glasshouse. Or by covering an outdoor crop with horticultural fleece.
Resistant Varieties
A solution, in part, is to grow a disease resistant variety. Not that any variety of potato is completely resistant to blight, but research has shown that varieties such as Cara, Home Guard, Pimpernel and Croft have a better resistance than others.
Some organic gardeners choose Golden Wonders because they find that, although the foliage is often completely destroyed by the disease, little damage is done to the tubers.
Damage Limitation
Opinions vary about what to do to limit the damage caused by blight once it has occurred. To prevent the disease spreading to the tubers, some gardeners cut all the haulms at ground level and take them away. Others believe that cutting the stalks helps blight to reach the tubers and prefer to delay digging the crop until after the first frost has killed the disease. Maybe they are both wrong and the spread of blight depends on the resistance of the tubers of particular varieties?
Blight Prevention
The most common form of blight prevention among organic gardeners is the use of copper sulphate in the form of Burgundy mixture. The formula is fifty grammes of copper sulphate and sixty grammes of sodium carbonate (washing soda) mixed with five litres of water. The mixture is sprayed on the foliage every ten days when blight conditions exist. It's often recommended in organic literature as an 'organic' spray, which it clearly isn't. But because its use goes back many generations, it is not considered as dangerous as modern chemical sprays.
Blight can also affect tomatoes. But few gardeners concerned with producing chemically free? food would want to spray copper directly onto their home-grown tomatoes. Some gardeners claim they prevent the disease by mixing crushed onions or garlic in water and regularly spraying the solution on their plants.
There is also some evidence that plants deficient in minerals are more susceptible to blight. If so, foliar feeding with fermented nettles, comfrey or seaweed would increase your plants' resistance to the disease.
At the moment scientists in Germany are working on a biological cure for blight using microorganisms found in compost heaps. A magic cure from muck?
Well known organic goat’s cheese makers, Inagh Farmhouse, have launched two new products in the St. Tola range. Named ‘Divine’ and...
