Symptoms of potato 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 underside of the leaf as the fungus blooms and releases more potato blight spores. In a short period of time, the entire plant will become blackened and die if not treated.
Infection avoidance – The organic way
Here are a few tips on coping with a potato blight outbreak organically.
- Remove all foliage as soon as you notice the first stages of potato blight, to avoid further infection. Harvest your crop after 2-3 weeks to ensure that blight spores on the soil surface are dead. After this time, the potato skins are thicker and a little more resilient to infection.
- Use only certified seed potatoes. Using potato cuttings and leftovers can quite often lead to outbreaks.
- Select blight resistant varieties (see list below). Although resistance is not 100% guaranteed, it will at least increase your chances of avoiding blight.
- Rotate your crop. Don’t plant potatoes on the same spot as last year. This will cut short the potato 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 potato blight. Do this by scraping the soil toward the tubers to form furrows.
- Check stored tubers for signs of potato blight and remove any infections immediately. Do this once a week.
Blight resistant potato varieties
- Sarpo Mira
- Lady Balfour
- Pentland Dell
- Sarpo Axona
Thompson and Morgan sell a great selection of Blight resistant potatoes.