Take care of your potatoes
Potatoes are growing strongly now. In most places they have been earthed up. Remember, when earthing, not to draw the soil up to a greater height than about 6 in. and do not leave a flat top or trough to the ridge. Finish it off to as sharp a point as possible. This prevents spores of potato blight from being washed down by rain to infect the tubers. Don’t try to earth up when the soil is wet.
To a large extent the danger of blight attack depends on the weather: if dry, only local attacks are likely and will not cause serious damage; given frequent spells of warm, moist weather, the tops may be completely killed by the end of July or in August.
The effect on the crop would be serious, if the tops were badly affected. The weight of crop would be greatly reduced; and if the disease spreads to the tubers themselves, they may rot in the ground or after you have stored them.
WHAT TO DO.
If you live within 10 or 12 miles of a large industrial centre, where the air is laden with fumes and smoke, do not spray, but seek advice locally: the secretary of your local allotment society, the horticultural committee of the council or the park superintendent should be able to help you.
And we think we’ve problems with air quality!
Gardeners who are not in areas likely to be affected by fumes from factories should, as a form of insurance against blight, spray their potato foliage with one of the copper-containing sprays recommended for the purpose.
Perhaps the simplest course is to buy one of the ready-made Bordeaux powders or pastes and apply it according to the maker’s instructions. Usually you have only to mix it with water and it is less trouble to prepare than a home-made mixture.
Note on Copper Based Fungicidal Sprays
Bordeaux and Burgundy mixtures, copper based fungicides, are fairly effective against potato blight.
They were mainly superseded by more complex chemical remedies.
Burgundy and Bordeaux mixtures were organically approved until quite recently but are now delisted.
Now the organic grower can only hope resistant varieties will resist the strain of blight attacking and non-organic home growers have little in the cupboard to help them.
If you have a hand-dusting machine, you could apply one of the powders made for the purpose —copper-lime or Bordeaux dust. Dust needs to be applied more often than sprays, however—four or five applications should be given, allowing a fortnight each.
