You may notice your sidewalk turning black this time of year. What’s happening? Time to look up.
I walk past a Saucer Magnolia every day when I come to work. It had beautiful flowers in the spring.
It looks pretty healthy from far away, but as you get closer, you can see sticky honeydew on the sidewalk
and plants below.
Honeydew is a sugary substance and is a waste product that comes from sucking insects that feed on the phloem of plants.
This honeydew will support the growth of sooty mold.
Some of these insects that feed this way include Aphids,
Spotted Lanternfly,
and soft scales
to name a few.
In this case, the magnolia is being fed on by Magnolia Scale. A close look shows the female scale in clusters on the branches of the tree.
The females are feeding and exuding honeydew that falls on everything below.
In the case of Magnolia Scale, we are approaching the time of year to treat the crawlers. A good explanation of how to approach treatment can be found in Joe Boggs’ BYGL Article attached:
https://bygl.osu.edu/node/2383
Another resource is a video by Dr. Dave Shetlar that speaks to many types of sucking insects and explains the true nature of honeydew:
https://www.youtube.com/watch?v=uei0QgUBZYE
If it’s sticky below, look up!
