Scale on Euonymous

Asked July 30, 2019, 6:13 PM EDT

Hello, I have what looks to be quite a bad infestation of scale on several euonymous bushes. It seems to be through the bushes, discoloring some areas and potentially killing a few branches, so I am wondering what treatment is recommended, and what the proper timing would be in our area. Thank you.

Montgomery County Maryland euonymus scale shrub

3 Responses

Here is our page on Euonymus Scale, a sucking insect.
https://extension.umd.edu/hgic/topics/euonymus-scale-shrubs

This shrub is pretty hardy. At this point we'd suggest either removing it or cut the plant back to the ground or healthy tissue and let it regrow. Keep an eye on the new growth and treat as needed.

Marian

Oof, not what I was hoping to hear but valuable information! These are a pretty significant, mature element in my landscape, so if I choose to cut them to the ground for regrowth rather than remove them, would there be any benefit to using horticultural oil preventatively as they regrow, to be sure to infestation is knocked out? Based on the fact sheet, I just couldn’t tell. I do have euonymus ‘Manhattan’ recently planted elsewhere in my yard so I want to be sure the scale doesn’t spread.

Euonymus japonica is susceptible to this scale. You have the option of cutting and letting it regrow. You can treat the crawlers with a summer rate of horticultural oil in May and June and August through September. Follow label directions and do not spray in high temperatures.
A dormant rate of horticultural oil can be sprayed to control light bark infestations when the plant is dormant. You have to read the label for application and timing.

Euonymus kiautschovica 'Manhattan' is relatively resistant to this pest. You have the option of replacing the plants with this species and may be a better plan. However, It is always good to diversify with some other plant species so you do not lose the stand to a disease or insect pest.

Marian