insects??? on pachysandra
Hi, In the early spring I noticed a few sections of my pachysandra seemed to be dying out. It seemed to revive, but now I'm noticing that the leaves are spotted yellow in some sections. When I looked at the underside of the leaves, I saw white aphid-like insects??? In some areas the stems are covered w/these white insects. What is this and how do I treat it? Thank you.
New Castle County Delaware
Your pachysandra appear to have a fairly heavy infestation of euonymus scale. The insect feeds on the plant and removes chlorophyll and plant cell contents; thus the yellow spotting on the plant. Males are white and females are a grayish brown. Crawler activity is usually more abundant around mid-July.
Common treatments for this scale insect is insecticidal soap during crawler activity. An application of insecticidal soap should contact all parts of the plant. Insecticidal soap may burn foliage if it is too hot; thus it may be better to use it on a small portion of the plant initially. Another option is to remove infested parts of the planting. A number of other products (pyrethroids, acephate, etc...) are available at garden centers for managing this pest but they also need to be applied during crawler activity. Read the label to find the amount to apply for this particular scale.
Thank you for your response. How long does it take to "heal" the plants (weeks, seasons, ?) Will I see some results fairly quickly? Do I need to do anything to the healthy patches of pachysandra so that it doesn't spread? Does euonymus spread?Our lot is 3/4 of an acre and there is A LOT of pachysandra! Is there anything we should do to prevent this from happening in the future? Thank you!
The damage will persist and the spotting may not recover. The product used to control the insect will determine how soon you achieve control, but usually within a few weeks to a month. You will need to continue to watch for the presence of the insect to be sure the populations are managed to the level you want. Euonymus scale has two generations a year and the insects hatch out of eggs to crawl to new locations. I would physically remove the worst infested pachysandra and treat those plants with low to moderate populations. There are no preventative treatments available for homeowners that work well to prevent the insect from crawling onto new plants, settling and beginning to feed. Those available for professionals are being used less since they are neonicotinoids, and there is concern about possible impact on bee populations (nothing is fully understood yet on the impact these insecticides have on bee health).