Shrivelled leaves and yellow spots appeared on my Japanese olive plant after a mealy bug attack, though that seems to have cleared up since I moved the plant into full sun. It is potted in an airy matrix, and I water it twice a week. What can I do to make it healthy again? 

Jeanette Poon

Your olive plant’s leaves look chlorotic and misshapen. It seems to lack nutrients.

The plant’s gritty, well-draining growing mix is good for aeration but does not retain nutrients well. You may want to add slow-release fertiliser pellets to the root zone, which will be a better method of nutrient delivery. Select pellets containing both the major nutrients and trace elements, which provide essential micronutrients.

Foliar fertiliser, which is specially formulated for spraying onto leaves, can also be part of your growing regimen.

What is wrong with my plant?

Chok Ken Sim

Can you scrape the brown particles off the leaves? If you can, your Ficus plant is probably infested with scale insects, a type of sap-sucking pest. An infestation of this severity will be difficult to manage, due to the amount of pesticide needed and the large surface area that has to be treated.