Potato blight is a fungal disease that can devastate a potato crop. The first sign of infection are black spots that appear on the leaves and then turn yellow. If left untreated, the plant will die back completely and can also affect the tubers.

How to avoid potato blight

• Before planting your seed potatoes, make sure you buy certified disease free seeds. Saving seed potatoes from previous years or using supermarket potatoes can result in problems later in the year.
• Variety choice. If possible, choose a variety of potato that offers some resistance towards blight. Most early potatoes offer very little resistance however they can generally be harvested before blight strikes.
• Earth up. Earthing up your potatoes with soil or other organic matter will help stop spores washing into the soil and infecting the tubers. This also helps reduce water loss from the soil meaning you don’t have to water so often. If you do need to water your potatoes, try to water the base of the plants.
• Check the blight forecast. Check out www.blightwatch.co.uk and sign up for blight alerts in your area.

What to do if you get blight
Should blight strike the first thing you should do is remove all the foliage from the plant as soon as you spot the first signs. After around 3-4 weeks you can harvest your crop. This will ensure the spores on the surface of the soil are dead and will also thicken up the skin on your potatoes. Dry off the tubers before storing them in a cool, dry, dark place. Do not wash them before storing.

Composting infected plants
Some people say don’t, while others say its fine. Personally I compost any plants that are infected by blight. I generally bury them in an established heap and find they break down in no time.