Arborvitae hedge struggling in Medford. - Ask Extension
Hi there, I have an arborvitae hedge that is browning, and I believe that spider mites and scale is causing the problem. The trees are 25 plus years o...
Knowledgebase
Arborvitae hedge struggling in Medford. #880446
Asked August 06, 2024, 5:11 PM EDT
Hi there, I have an arborvitae hedge that is browning, and I believe that spider mites and scale is causing the problem. The trees are 25 plus years old, and they are getting adequate water. Is there some sort of application that is suggested for killing the mites and the scale? If so, can you include instructions for the application? If the chemical must be sprayed by a licensed applicator, then do you have a good suggestion for the applicator? Thank you.
Jackson County Oregon
Expert Response
Spider mites are a damaging pest to arborvitae and other conifers. They feed on the sap and chlorophyll of the leaves, causing a stippled appearance and eventually turning the needles yellow, brown, and causing them to fall off. Severe infestations can kill the plant. Here are some ways to get rid of spider mites on arborvitae:
- Hose down: Use a garden hose to dislodge the mites. Spider mites dislike getting wet.
- Insecticidal soap or oil: Spray the leaves with a mixture of 1 quart of water and 1 teaspoon of dish soap several times a day for two weeks. You can also use insecticidal oils, such as neem, canola, or cottonseed oil.
- Isolate: Isolate the affected plants so they don't spread.
- Fertilize: Use a slow-release or low-nitrogen fertilizer, as high nitrogen levels encourage reproduction.
- Water: Keep the arborvitae hydrated, but not too much. Healthy plants are more tolerant of damage, while drought-stressed plants are more susceptible.
