Late blight

This destructive disease is caused by the pathogen, Phytophthora infestans. Grow a blight resistant variety (‘Consuelo’ and ‘Mountain Magic’ did well in our trial). Wet foliage aids its spread so avoid overhead irrigation of outdoor plants in vulnerable periods (see blightwatch. co.uk). Greenhouse plants are less vulnerable; move outdoor potted plants under cover in warm, wet weather. If blight strikes, pick off and destroy mildly damaged leaves, and if the whole plant is affected, dispose of it (don’t compost).