GARDEN GURU

Q I sprayed and cut the leaves of a small willow tree after discovering they were covered with a yellow powder. But it’s back, and rapidly covering the tree. What can I do?

Yvonne Scott

A It sounds as if your tree is under attack from willow rust, a common fungal disease that can lead to trees dropping their foliage prematurely. Rake up and destroy all fallen leaves in autumn and spray with a suitable fungicide in spring, just as leaves start to open. Provanto Fungus Fighter Plus and Fungus Clear Ultra will both do the trick.

Q A weed with purplish, clover-like leaves and yellow flowers is appearing all over our garden. What is it?

Neil Traynor

A The plant in the photo you emailed to me is Oxalis corniculata, a vigorous, creeping plant that’s a prolific self-seeder.

Tease it from the ground, making sure you remove as much of the root system as possible.

Q Back in spring I planted some canna lilies in pots that flowered brilliantly all summer. What should I do with the plants now?

Jamie Henderson

A It depends on where you are. If you live in a mild area, move pots into a rain shadow over winter, standing them on bricks to allow excess moisture to drain freely. Also, cut back all top growth once it withers. Those in colder or damper parts should move pots into a garage, shed or cool greenhouse – as plants are dormant, there’s no need to water.