Crape Myrtle CMBS - Ask Extension
I have identified what I believe to be Bark Scale on my Crape Myrtle tree. In researching treatment it appears that the product recommended is not ava...
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Crape Myrtle CMBS #867176
Asked May 06, 2024, 8:22 AM EDT
I have identified what I believe to be Bark Scale on my Crape Myrtle tree. In researching treatment it appears that the product recommended is not available in this area (Ferti-lome tree & shrub systemic insect drench) .Other recommended are also not sold. What is the recommended treatment in my area ?
Montgomery County Maryland
Expert Response
James, you don't say where you are but to comply with Maryland law, if using a neonicotinoid systemic, you must hire a professional to apply it.
Here is more info on the Crapemyrtle bark scale from U of Md Extension:
https://extension.umd.edu/resource/crapemyrtle-bark-scale-new-problem-home-landscapes/
Thanks for contacting Ask Extension.
Here is more info on the Crapemyrtle bark scale from U of Md Extension:
https://extension.umd.edu/resource/crapemyrtle-bark-scale-new-problem-home-landscapes/
Thanks for contacting Ask Extension.
Thank you for your response. I am in Montgomery County. Is there a DYI solution that is not neonicotinoid systemic that I can acquire and spray. I was thinking maybe Bonide Horticultural oil. Is that effective for control? Or do I need an arborist to handle the problem? the tree is about three years growth. In reading the material, I'm thinking that we may have over pruned the tree in an effort to control growth as it is in front of the house garden. Are other common plants subject to the problem?
Regards,
Jim
Jim
Hello Jim,
Like many scale insect species, Crapemyrtle Bark Scale is named for one of its prominent host plants, but it is not restricted to that species or even that plant family; it can utilize a wide range of unrelated plants. That said, this particular scale insect is fairly new in our region and research is ongoing as to what species of plants it can feed and reproduce on successfully. So far, we've really only seen it on crapemyrtle and purple beautyberry.
As noted on our Introduction to Scale Insects page, horticultural oil can be a treatment option as a topical insecticide (that is, it will only impact the insects it contacts directly, and dried residues do not have any affect). The target with these applications are the crawlers, so since we are still collecting data on exactly when that tends to happen in Maryland for this scale, we can only guess as to the date. Based on limited observations so far, that seems to be sometime around mid-June for the first peak of crawler activity (for central Maryland, anyway). Overlapping subsequent generations can occur later into the summer (late August and early October peaks have been observed, but we need to see how consistent that is from year to year), and this scale species seems to have at least two full generations per year here, maybe three. Dormant oil, the winter dilution rate of horticultural oil, can be applied once foliage has shed for the winter to help suppress overwintering scale.
Bear in mind that dead/dying scale won't necessarily look different or fall off the plant right away, so a treatment might be working while not necessarily changing the appearance of the infestation for some time. Eventually, they will wear off.
Since pesticide sprays, including lower-toxicity options like horticultural oil, need to be applied very evenly and thoroughly to be effective, if a plant is too tall to reach with a home sprayer, hiring a professional can still be the best course; they will have professional-grade equipment that is kept calibrated and can produce the right droplet size to coat the bark well and/or which will have enough water pressure to reach higher canopies.
Miri
Like many scale insect species, Crapemyrtle Bark Scale is named for one of its prominent host plants, but it is not restricted to that species or even that plant family; it can utilize a wide range of unrelated plants. That said, this particular scale insect is fairly new in our region and research is ongoing as to what species of plants it can feed and reproduce on successfully. So far, we've really only seen it on crapemyrtle and purple beautyberry.
As noted on our Introduction to Scale Insects page, horticultural oil can be a treatment option as a topical insecticide (that is, it will only impact the insects it contacts directly, and dried residues do not have any affect). The target with these applications are the crawlers, so since we are still collecting data on exactly when that tends to happen in Maryland for this scale, we can only guess as to the date. Based on limited observations so far, that seems to be sometime around mid-June for the first peak of crawler activity (for central Maryland, anyway). Overlapping subsequent generations can occur later into the summer (late August and early October peaks have been observed, but we need to see how consistent that is from year to year), and this scale species seems to have at least two full generations per year here, maybe three. Dormant oil, the winter dilution rate of horticultural oil, can be applied once foliage has shed for the winter to help suppress overwintering scale.
Bear in mind that dead/dying scale won't necessarily look different or fall off the plant right away, so a treatment might be working while not necessarily changing the appearance of the infestation for some time. Eventually, they will wear off.
Since pesticide sprays, including lower-toxicity options like horticultural oil, need to be applied very evenly and thoroughly to be effective, if a plant is too tall to reach with a home sprayer, hiring a professional can still be the best course; they will have professional-grade equipment that is kept calibrated and can produce the right droplet size to coat the bark well and/or which will have enough water pressure to reach higher canopies.
Miri
