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Bonsai are prone to the same diseases and pests that attack these trees, but because they are small and compact, it doesn’t take long at all for a localized problem to spread over the entire tree, with disastrous results. And because it grows slowly a bonsai is less able to outgrow an infection., or a plague of aphids, iii the same way a full-size tree can.

A twice-yearly precautionary treatment with a systemic insecticide and fungicide will help, but it will not be one hundred percent successful. (Systemic chemicals are designed to he absorbed by the plant and fight the problem from the inside.) Deciduous trees will benefit from a normal garden ‘winter wash’.

Constant vigilance is necessary throughout the year. Once a problem has been spotted and diagnosed remedial action should be taken immediately, using an appropriate commercial treatment.

Always read the pack to make sure the treatment is effective for your particular problem, and follow the manufacturer’s instructions to the letter.

If one brand doesn’t appear to work try another - some insects seem to be able to build up a tolerance if the same brand is used all the time.

Trees may take weeks to recover from fungal infections, so don’t lose heart. If the symptoms stop getting worse, the treatment has more than likely worked.

Never rise systemics on Chinese elms. They will not kill the tree but the foliage will yellow and fall and fine twigs may die back.