Star Magnolia sap dripping

Asked June 23, 2020, 1:02 PM EDT

We have a Star Magnolia in our front yard for 20-30 years. Last year it started dripping sap. We didn't check on it then, and this year it is again, even more so. Help! We read that it is magnolia scale and there is a window for treating it. Can you please help us with how to control it? Thank you!!

Montcalm County Michigan

1 Response

Dripping sap is a symptom that can be caused by magnolia scale. We have started to receive reports of magnolia scale in MI, and it's possible this is the cause. I'd advise searching the tree to see if you find any scale adults (https://www.canr.msu.edu/news/check_magnolias_for_magnolia_scale_now)

There's also a possibility the sap could be due to a canker. Check here to rule out that the dripping sap does not resemble this pattern. https://ag.umass.edu/landscape/fact-sheets/phytophthora-bleeding-canker

June to early July is the time to apply systemic insecticide so that it has time to move from roots up to twigs. You can do this yourself but you must read the label, calculate the correct amount to use for your size tree, purchase that amount and apply it 4-8 weeks ahead of when the crawlers are active.

August through September is usually active crawler time in Michigan and is the time to apply a contact insecticide spray to manage the crawler stage. If you choose the systemic you should not need the spray. Follow all label directions to avoid damage to the plant or to people.