A hole in your hedge?

We have been seeing a number of hedges around Calgary the last few years that are severely infested with Oystershell Scale. The damage appears as large sections of the hedge that “dieback” or fail to leaf out due to the infestation. This results in a very patchy, ragged look.

Oyster shell scale on Cotoneaster

As you can see in the picture, the insects are shaped like small Oyster Shells. They are part of a group of insects called “Armored Scale”. They are given this name as the outer shell of the Adult insect is “armored” which makes it impenetrable to traditional pesticide sprays. This makes timing imperative when deciding to have your hedge treated. The insect is susceptible at an early stage in June before it had developed its armored coating.

The best defense against Oystershell Scale is prevention, keep your hedge healthy by thinning the thick ends of branches and stems to allow more light and air penetration to the inner canopy. When shaping, attempt to leave the bottom of the hedge a few inches wider than the top, this allows for more light to be absorbed by the lower branches helping to keep them healthy and pest free.

We have lots of information on this insect available on our pest and disease page >>Oystershell Scale