Potato blight is a nasty disease that can totally devastate a crop within a couple of days, turning your fine potatoes into black mush. This fungal disease is becoming increasingly common in the UK due to the favoured damp summers that we have had of late. Blight can infect both the tuber or the leaves and stems.
Symptoms of blight
The first signs are the development of dark spots on leaves, rapidly turning the infected leaves yellow. You will also notice a whitening on the under-side of the leaf as the fungus blooms and releases more blight spores. In a short period of time, the entire plant will become blackened and die if not treated.
Blight avoidance – the organic way
Here are a few tips on coping with a potato blight outbreak organically on your allotment patch.
- Remove all foliage as soon as you spot blight to avoid the infection washing down the stems onto the tubers. Harvest your crop after 2-3 weeks to ensure that blight spores on the soil surface are dead and potato skins are thicker.
- Use only certified seed potatoes. Using potato cuttings and left overs can quite often lead to an outbreak.
- Select when possible blight resistant varieties (see list below). Although resistance is not 100% guaranteed, it will at least increase your chances of dodging blight.
- Ensure that you rotate your crop; don’t plant potatoes on the same spot as last year. This will cut short the blight growing cycle as the fungus desperately awaits your next crop after the dormancy of winter.
- Earth up your potatoes to protect the tubers from blight.
- Check stored tubers for signs of blight and remove any infections immediately.
Blight resistant varieties
First earlies
Premiere, Orla
Second earlies
Nadine, Cosmos
Main crop
Cara, Romano, Kondor, Sarpo Mira, Brodick, Sante, Balmoral, Lady Balfour, Valor, Pentland Dell, Sarpo Axona, Stirling, Spunta