Hi, I just removed two large 30 year old beautiful shrubs with euonymus scale on them that I tried to save for 3 years and lost and would like to know if the ground is now OK to plant new shrubs of the same in the spot?
Thank you for contacting the Toronto Master Gardeners with your query.
What a shame that your two beautiful Euonymus bushes ultimately succumbed to Euonymus scale (Unaspis euonymi). I can understand why you would want to replace them with the same species. However, most evergreen Euonymus are susceptible to an attack from scale, especially E. japonicus and E. fortunei.
There are two types of scale, soft and hard. Euonymus scale belongs to the latter armored type. This scale has several generations in one season, making them a challenge to control. The adult scale feed on the plant fluids in the same spot under this protective coating. Eggs hatch under the female covering, turn into ‘crawlers’, move to another part of the plant, create a cover and stay there permanently to continue feeding.
Plants that are under stress are most susceptible to scale. Make sure you water your new plant regularly, especially during dry spells since the insect is sucking the fluids out of the plant. A good layer of organic compost under the plant will help retain moisture in the soil and feed the plant at the same time.
Keep a close eye on your new plants, checking every two weeks for symptoms. Leaves will develop yellow spots. Adult males are visible on the underside of leaves as white specs. You may want to spray your plants with dormant oil (available in garden centres) in the late winter/early spring which will suffocate the scale. If you still see the beginning of evidence of scale, you can scrape the scale off or just cut off the branch.
Good luck with your new Euonymus shrubs.