Potato blight

What is Potato Blight?

Potato blight, also known as late blight, is a fungal disease that wreaks havoc on tomato and potato plants, causing leaves and fruit to turn yellow, blacken, and rot within a matter of days. The presence of white, mouldy ‘threads’ or ‘whiskers’ on the underside of leaves further confirms the presence of this dreaded disease.

The onset of blight is an allotment gardener’s worst nightmare, capable of wiping out an entire crop with alarming speed, especially during wet weather conditions. It’s a disease that can spread rapidly, making prompt action crucial to prevent its spread and minimise damage to your precious tomato plants.

What to do if your tomatoes develop Blight

If you notice the telltale signs of blight on your tomatoes, swift action is essential. The first step is to remove and destroy all affected plants. Do not attempt to compost them, as this will only serve to spread the fungal spores and perpetuate the blight problem. Burning is the most effective method of containing blight and preventing its spread to healthy plants.

How to prevent Blight

Never grow tomatoes or potatoes in 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 or 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.

Moisture Management

Avoid overhead watering, as this can spread fungal spores. Instead, water at the base of the plants to keep the foliage dry.

Thompson and Morgan sell a great selection of blight-resistant potatoes.

This Post Has 2 Comments

  1. Howard Templeton

    I saw a gardener give a tip to Rick about preventing potato blight on one of Rick Stein’s Cornwall tv series, recently. “Mix 1 part whole milk to 10 parts water and spray before blight appears” old wives tale or not I’ll give it a go.

  2. James Middleton

    Sounds like a good idea worth pursuing. Mix a little bi-carb and Neem oil in there and you should have a killer formula! 🙂

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