Sap-feeding scale insect leaving shrub branches bare
Question: About a month ago I noticed that the leaves had fallen from the centre of this shrub at the front of my bungalow leaving bare branches which were heavily infested with some sort of disease or insect but, at the same time, there would appear to be new buds forming on the end of these branches. I wonder, therefore if there is any hope of survival for this plant or is it destined for the green waste bin? (Mr A Tolver, Hoveton)
Answer:
The problem you have on your shrub is Euonymus scale. This sap-feeding scale insect Unaspis euonymi is particularly attracted to Euonymus japonica, although it will feast on other evergreen euonymus too.
The white males congregate on the leaves, but the brownish-black females live on the bark, making them hard to spot.
Large numbers cause yellowing of the leaves, dieback and loss of vigour.
They are most visible from mid-July to early September.
With light infestations, you can control the problem by scraping off the scales by hand and dispose of them. For heavy infestations, prune out those branches that are badly affected.
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Spray with a plant oil wash in winter if you don't want to use non-organic chemicals. If you are willing to use chemicals spray the young scales in mid-July and early September with a systemic insecticide containing imidacloprid or thiacloprid. These are in Provado the ultimate bug killer.
The buds breaking at the end of the leaves is more down to the plant having one last go at getting over the problem with the scale.
This Euonymus is about as badly infested as I have ever seen so you may be best advised to remove it and plant something unrelated to Euonymus in its place. And clean the area thoroughly with Jeyes fluid or similar to kill all the scale insects that are in the area.
•This article was first published on November 17, 2011.
