Have your tomatoes gone brown? It could be blight...

TOMATO blight is among the most frustrating diseases for gardeners. You spend months growing and nurturing these beauties when that telltale brown stalk appears, spreading like wildfire to decimate the fruits of your labour and, before you know it, you’ve lost the lot.

I always consider late blight to be the most brutal of diseases, just when all your tomatoes are starting to ripen and you have already harvested quite a few, which is what has happened to me this year.

So, is there anything you can do to prevent the late summer scourge decimating your tomato crop?

WHAT CAUSES TOMATO BLIGHT?

Generally, it is warm, humid weather from mid-summer onwards, when temperatures are above 10C (50F) and your crops don’t have adequate ventilation. Spores are spread by wind and rain – and can be carried up to 30 miles – needing only a minute film of moisture on the foliage to cause damage. Late blight (Phytophthora infestans) is fatal to the plant.

WHAT ARE THE SYMPTOMS?

Initially dark spots or brown patches appear on the leaves, which curl up and wither, followed by fastspreading brown patches on the stems as the disease makes its way rapidly to infect the fruits, which turn brown, leaving them inedible.

The tomatoes will develop a brown discoloration and may appear to shrink inwards, quickly dropping off the diseased stems.

Potatoes may also be attacked, although they succumb slightly earlier than tomatoes.

HOW DO YOU DEAL WITH IT?

You could spray every two weeks with Bordeaux Mixture – a combination of copper sulphate, lime and water – available from garden centres.

As the main ingredient is copper, it’s not off limits for organic gardeners. It’s likely to be effective only if you spray early as a preventative measure, not once the