Cotswolds Garden - FAQs
Frequently asked gardening related questions
If your magnolia is covered in a sticky residue, it's almost certainly honeydew, a sugary substance excreted by sap-sucking insects, most commonly scale insects or aphids. Inspect the underside of leaves and stems for these pests. The honeydew can then lead to the growth of sooty mould, a black, non-harmful fungus that lives on the honeydew itself, not the plant. To resolve this, you need to control the underlying pest infestation using appropriate methods like horticultural oil or insecticidal soap, or by encouraging natural predators.