QHow do you prevent tomato blight now we don’t have Bordeaux mix? Jennifer Elsden, Gwynedd

After a lack of heat, the biggest problem for outdoor tomatoes is the risk of blight. This manifests itself as pale-brown blotches on leaves that will quickly spread into a circle of softly collapsing and browning leaves. The fungus can then get to the fruit, making them inedible. The best means of avoiding it is to grow your tomatoes under cover and not over water them, as the blight is spread when it’s damp and needs humid conditions to develop. If you have to grow them outside, choose blight-resistant varieties such as ‘Crimson Crush’ or ‘Mountain Magic’, and give the plants maximum ventilation by spacing them as widely as you can. At the first sign of blight, remove all affected leaves and fruit, and strip away all remaining foliage to expose the green fruit to maximum light and air. By August, tomato fruits will develop perfectly well with no leaves at all, so this isn’t a disaster although it does look pretty dramatic. If the plant isn’t rescuable, remove it and burn it.