Warm and damp summer weather provides the ideal conditions for pests and diseases to proliferate, especially now that plants have lots of soft new growth, which is very susceptible to attack. But don’t panic – not all problems are serious.
Read our troubleshooting guides.
Use our guide to find out what is affecting leaves in your garden.
Apple and pear scab
Symptoms: Greenish-grey scabby spots appear on the leaves, which may fall prematurely.
Treatment: Bin affected shoots, and pick up fallen leaves – the fungus that causes scab can overwinter on them.
Read more about apple and pear scab.
Symptom: Froth appears on leaves and stems. It contains a froghopper nymph.
Treatment: The nymph does little damage but if you’re bothered about it, wipe it off.
Find out more about cuckoo spit.
Symptoms: Red lily beetles and their larvae can ravage the leaves of lilies and fritillaries, making holes in them.
Treatment: Inspect plants regularly for the adults and larvae; squash or spray them.
Read more about dealing with lily beetle.
Symptoms: Adults nibble the leaf edges, while the larvae of vine weevils eat roots, which can cause the plant to die without it showing any problems.
Treatment: Use a biological control.
Read more about treating vine weevil.
Symptoms: Distortions caused by various organisms, often harmless.
Treatment: Bin the damaged parts of small plants.
Peach leaf curl
Symptoms: Blistered, red leaves fall early from peach, nectarine, apricot and almond trees.
Treatment: Shelter the plant in winter with plastic. Bin infected leaves early.
Discover more about peach leaf curl.
Symptoms: Brown-orange marks, worse when it’s damp.
Treatment: Water plants at the base to avoid wetting leaves. Give a balanced feed to susceptible plants.
Read more about rust.
Symptoms: Yellowing, dying, spiralling or narrow growth.
Treatment: Cut out affected shoots and feed plants.
Symptoms: Protected under waxy scales, the scale insects suck sap.
Treatment: Try a winter wash on trees, and use biological controls indoors.
Read more about scale insects.
Symptoms: Weak growth, poor or misshapen crops, yellow or discoloured leaves.
Treatment: Feed the plant with a balanced feed. Liquid feeds are absorbed the quickest.
Symptoms: a white dusting covers the plant and causes dieback.
Treatment: Water well at the base of plants. Bin affected shoot tips.
Read our articles on mildew.
Symptoms: The bugs eat many small holes in the leaves.
Treatment: Tidy nearby weeds and spray with insecticide.
Find out more about treating capsid bugs.
Symptoms: Slugs and snails devour plants at night, leaving large holes, and are more active in wet weather.
Treatment: Use organic slug pellets, nematodes or traps and barriers.
Symptoms: The caterpillars feed on the leaves that they have bound together with webs.
Treatment: Crush them by pinching the leaves together.
Symptoms: The leaves of roses have purple-brown blotches; the leaves then turn yellow and drop off. The stems may also be affected.
Treatment: Pick up and destroy fallen leaves. Cut out any affected stems when pruning. Spray with a fungicide. Choose resistant varieties.
Find out more about dealing with and preventing rose black spot.
Symptoms: On potatoes and tomatoes, yellow/brown patches spread over foliage, killing the plants.
Treatment: On potatoes, bin all top growth (don’t compost it). Dig up the potatoes after two weeks. Remove affected tomato plants so that the disease doesn’t spread to other plants.
Symptoms: Insect larvae make tunnels in leaves.
Treatment: Mostly ignore, but protect onions and leeks with fleece.
Find out more about leaf miners.
Symptoms: Many, including stunted, distorted or mottled growth.
Treatment: Bin affected plants.
Symptoms: Pigeons tear leaves with their beaks, leaving ragged edges.
Treatment: Scare them off and protect vulnerable plants (such as brassicas) with netting.