Knowledgebase
Crape Myrtle Bark Scale #867869
Asked May 10, 2024, 11:38 AM EDT
Good morning. I have a small crape Myrtle that has exploded with bark scale essentially overnight. I plan on trying to wash it with soapy water, but it looks too far along for that to make a difference. I’ve read about the soil drench insecticide options , but would like to avoid insecticide if possible. Are there any other remedies that you suggest? I would also note that a number of cats live in the area, and I would be curious if you know if the soil drench could negatively impact them. I’ve included photos of the tree. Thank you!
District of Columbia County District of Columbia
Expert Response
Good morning! I'm sorry to hear about the sudden onset of the crape myrtle bark scale on your tree. If you're looking for non-chemical options, you could consider a few methods:
1. **Physical Removal**: Scraping the scales off with a brush or cloth can help reduce the population. This is most effective when the scales are not yet encrusted and are still soft.
2. **Soapy Water**: While you mentioned that it might be too late for this, a gentle soapy water spray can help dislodge the scales. It's best to do this early in the day so the tree has time to dry off before the evening.
3. **Horticultural Oils**: Horticultural oils can be applied to the tree, but they should be applied when temperatures are above 45 °F and below 90 °F to be effective. They can help control the scales by suffocating them, but they may need to be applied multiple times for best results [2].
4. **Prune Affected Branches**: Pruning can help reduce the scale population by removing the affected branches. This is most effective when the tree is dormant, typically in January or February [1].
As for the safety of these methods for cats, horticultural oils are generally safe for pets, but it's always a good idea to keep them away from the treated area until the oil has dried. Soapy water is also safe for pets, but you should rinse the tree thoroughly after applying it to ensure no soapy residue remains.
If the scale infestation is severe, it might be necessary to consider a soil drench insecticide, but you should consult with a local extension service or a professional to determine the best product and timing for application. If you're concerned about the safety of these products for your cats, you can also consider using a systemic insecticide, which is applied to the soil and absorbed by the tree, rather than a contact insecticide that needs to be sprayed directly onto the tree [3]. The downside of using a systemic insecticide is that it is absorbed into the leaves and flowers, and hence could impact other insects and bees.
Remember, early detection and treatment are key to managing crape myrtle bark scale effectively. If the infestation is severe or you're unsure about the best course of action, I recommend contacting your local arborist service for more personalized advice.
Here is a link to further information. Please let us know if you have further questions.
Lesley
DC Master Gardeners
