Mite fever...

Bob explains how you can protect your greenhouse crops in hot weather if they fall prey to red spider mites

- Bob Flowerdew

THE giveaway is that your plants undercover start to look pale, with a sort of sickly yellowing. Look closer, and you may see that each leaf has a multitude of tiny pin pricks. If you have excellent eyesight, you may be able to see tiny critters moving around. These are not red but buff-looking – a bit like minuscule spiders. But they are not spiders: rather, they are red spider mites. The confirmatory sign is fine cob webbing over the youngest shoots of plants.

These pests are mainly a problem when the weather is hot and dry, and less so in a cold, wet year. In very warm summers, they may even bother plants outdoors, particularly if those plants were started undercover and carried the pests out with them. They are mostly a nuisance undercover, though, and will spread on to most plants.