ASK DIARMUID

QWehave a laburnum tree in our garden overhanging a 14ft x 7ft pond and nearby table and chairs. We’re used to having the yellow flowers dropping, followed by the pods which we net up regularly when we need to – but we now have a sticky substance dropping onto the table and chairs and into the pond.

It appears to be covering the lily pads and other pond plants and also laying on the water surface. This has never happened before in the 25 years we’ve been here.

We have wiped and moved the furniture, but are more concerned about how it affects the pond and the fish. We would be grateful if you could possibly advise us on what this may be and what we can do about it.

Sue and John Mills

AThis

sounds like a case of honeydew – a sticky substance excreted by aphids – greenfly or blackfly – a very common presence in gardens and they like to suck sap from trees and shrubs and then freely deposit the end result you are seeing.

They are probably not doing harm to your tree but are more of a nuisance. Likewise, I don’t think honeydew would be harmful to pond life.

Aphids can be removed by hand or hosed off but this may not be practical depending on the size of your tree.

Instead, you could encourage natural predators such as ladybirds which are capable of eating as many as 50 aphids a day.

They will appreciate you growing herbs such as mint, fennel and dill, and flat-topped flowers such as yarrow as well as a messy little spot of logs, leaves or uncut perennials so that they can overwinter in comfort.