Blight is an extremely common disease that affects tomatoes and potatoes. It can be easily identified as leaves and fruit start to turn yellow and then black within a matter of days. You may also notice white mold ‘threads’ on the underside of leaves.
The onset of blight is the allotment gardeners worst nightmare and can totally devastate a crop with very little warning. It is noticeably worse in wet weather
What to do if your tomatoes develop Blight
Firstly (and this applies also to potatoes), pull up and destroy all affected plants. Do not compost them as this will only spread the problem as the fungal spores will transfer to the compost to wreak havoc another season. Burning is the best method of containing blight. There really is no reasonable hope for a blight infected tomato.
How to prevent Blight
- Never grow tomatoes or potatoes on the same spot for at least three years. Crop rotation is a good method for avoiding many diseases and pests.
- If you are growing your tomatoes on an allotment, ask your neighbouring plot holders where they grew their tomatoes and potatoes last year as it is a good idea to plant your crop as far as possible from last year’s crop.
- Before blight starts, spray your crop with copper fungicide in June/July and then repeat a few weeks later.
- There are a number of blight resistant varieties of tomato on the market such as ‘Ferline’ or ‘Totem’.
- If you are growing tomatoes in a greenhouse, then ensure that there is plenty of ventilation. This will minimise the chances of blight infection.