The disease hurting tomatoes is caused by a fungus-like organism that causes the fruit to rot quickly and spreads through the foliage, causing stems to collapse and decay.
Tomato yields could be the worst for years after storms and torrential rain damaged crops, the Royal Horticultural Society (RHS) has warned.
Guy Barter, the RHS chief horticulturist, said: “As a result of wetter summer weather in places, there are higher numbers of slugs and more blight than we have had for several years. Blight spreads like wildfire in wet conditions. The good news is, there is less watering to do.”
A spokeswoman for Waitrose said “it’s been a challenging year for our growers” and said the “changeable weather” has led to late harvests.
Jack Ward, the chief executive of the British Growers Association, said climate change is creating new challenges for domestic and commercial gardeners.