What is the dreaded blight?
Potato and tomato blight is a disease caused by a fungus-like organism that spreads rapidly in the foliage and tubers of potatoes in wet weather, causing collapse and decay. The blight organism enters the leaf of a tomato or potato when it is covered with a film of water and the temperature is warm.
How can blight be prevented?
Blight on tomatoes or early potatoes grown in polytunnels or glasshouses can be controlled by keeping the leaves dry. This can be achieved by watering carefully on to the soil and not getting the leaves wet, combined with ventilating well. This is obviously easier said than done with outdoor potatoes or tomatoes.
Planting a blight resistance variety of potato such as Orla for an early, and the Sarpo varieties (such as Axona & Mira) for a maincrop is probably the best way to minimise the impact of blight.
Check regularly for signs of infection and know how to recognise it. It starts as brown patches on the leaves with a yellowish border. It soon infects the stalks and travels into the tubers in potatoes.
Make sure potatoes are well earthed up to prevent spores getting into the tubers from the leaves.
If you get blight what do you do.
If your plants have blight removing the effected area can be enough to prevent it spreading. In potatoes this means cutting them right back to the soil and leaving the tubers underground.
In tomatoes, our Head Grower Richard has a somewhat unorthodox method. He removes the tomato stems but leaves the side shoots on so the plant can continue to photosynthesise.