Blight. Not great for tomatoes and potatoes.



At this time of year, it’s worth being vigilant for signs of blight. It has a habit of making itself a nuisance in late summer with the warmer weather, especially if it’s wet and humid, and the last thing you want is to see your potato patch or your pots of juicy tomatoes being totally annihilated at the last hurdle.

What does blight look like?

Take a look at your potato and tomato plants (it usually affects tomatoes grown outside rather than in the greenhouse.) If you see some brown patches on the leaves that’s your first warning sign. If it’s more advanced, you may see brown patches on the stems as well, and the leaves will have started to rot. If things are really bad, your potato tubers will be brown and rotting and your tomatoes will have rotting patches too. Not good.

What can I do about it?

If you catch blight early enough then you can probably save your crop.

For potatoes, cut the foliage off altogether at the stems. Be sure to get rid of the foliage ideally by burning it on a bonfire to prevent the disease spreading to other areas of the garden and infecting next years crop too. Leave the potato tubers in the ground for two weeks. This will let the potato skins harden. Then dig them up.

For tomatoes, cut off any affected vines, leaves and stems, and as with potatoes burn them to prevent the disease spreading. Keep an eye on things over the next few days. If the tomatoes do not show signs of infection (i.e. no brown rotting patches) then pick them. You can eat the ripe tomatoes but do NOT eat them if they are infected. For unripe tomatoes, pop them on a sunny windowsill to ripen. If they develop any brown patches, it’s game over and you’ll have to get rid of them, but you might be lucky!

How do I prevent it next time?

Firstly, it’s really important to get rid of any infected plants this year and destroy them. Any tubers or tomatoes that remain in the ground are likely to grow next year into little disease carrying plants that will infect your new crop. If you do see any surprise growers next year, pull them out and get rid of them.

Spacing is important for airflow to prevent the disease spreading, so make sure you plant your potatoes and tomatoes with plenty of space next year.

Don’t grow your potatoes or tomatoes in the same bed two years running. Crop rotation is really good for this and we’ll be delving into this in more detail in another post later in the year.