If you are asking yourself; “Why has my conifer tree turned brown”, your tree may have fell victim to the pest known as Cypress aphid (Cinara cupressivora).
It’s possible that the browning is due to poorly stored de-icing salt, drought or wind damage but over the last five years in Scotland I have noticed that this problem has become more prevalent and it is most likely due to the Cypress aphid moving further north.
Around seven years ago I attended a tree pests and diseases seminar organised by the Arboricultural Association in Perth. When they showed a couple of images of conifer hedges or trees that had brown patches I thought that the owner had maybe just been a little over zealous with their hedge-cutters on a frustrated Sunday afternoon. When they confirmed that the culprit was in fact something called Cypress aphid but that it was confined to trees and hedges in Southern England I concluded that I could just ignore this section.
So it took me by surprise when I noticed a row of 15m conifer trees in one of my long-term client’s front garden in Clarkston in the South side of Glasgow start to exhibit signs of dessicaiton.
I immediately remembered the information in the lecture and unfortunately had to remove his trees along with the stumps and then replant a more resilient species that wouldn’t look out of place.
What is Cypress aphid?
It is a tiny insect that works in large numbers to dry out particular conifer hedges and trees by feeding on the sap during the summer.
What are the signs?
- new growth turns yellow in summer eventually turning brown and dying off
- brown patches on hedges
- black sooty mould on foliage
- lower parts of hedges can be particularly vulnerable
- eventually the entire tree or hedge might die
The ubiquitous Leyland and Lawson Cypress will be affected in numbers and result in a real change to the landscape in parks and gardens but some other lesser known species are also affected, namely Thuja occidentalis and Cupressus macrocarpa.
What is the solution?
- Regular trimming of hedges throughout the summer will ensure they will be less affected
- Organic sprays designed to control aphids are the safest solution but are only practical for smaller trees and will need to be constantly reapplied
- Tree Wise Tree Surgeons do not endorse the use of pesticides due to their known harmfulness to either humans and/or pollinating insects
- Tree or hedge removal and then replanting may be the only solution
If you suspect your conifer tree or hedge may be infected with Cypress aphid we would be happy to carry out an inspection. Contact us today on 07969306387