Magnolia tree honeydew - Ask Extension
I need help knowing just when to spray my magnolia tree in order to stop the honeydew. I understand it is at a certain growing degree day, but I’m n...
Knowledgebase
Magnolia tree honeydew #878325
Asked July 22, 2024, 5:41 PM EDT
I need help knowing just when to spray my magnolia tree in order to stop the honeydew. I understand it is at a certain growing degree day, but I’m not clear just how to calculate that any help would be appreciated.
Oakland County Michigan
Expert Response
Hello James,
Treating the crawler stage of magnolia scale is at GDD base 50 - 1900-2000. We are approaching that, probably sometime in August.
Today we are at 1633 GDD base 50, in Waterford MI.
See the attached pictures of the GDD Tracker, attached- I have circled in red the pertinent areas on the screens.
To use this tool, go to this website:
https://gddtracker.msu.edu/?model=7&offset=0&zip=48327
Enter your zipcode near the top of the page.
Scroll down the dates in the left hand column(these are for 2024).
The second column from the right within that 2024 group of dates is GDD base 50.
If you have any questions, please ask.
Treating the crawler stage of magnolia scale is at GDD base 50 - 1900-2000. We are approaching that, probably sometime in August.
Today we are at 1633 GDD base 50, in Waterford MI.
See the attached pictures of the GDD Tracker, attached- I have circled in red the pertinent areas on the screens.
To use this tool, go to this website:
https://gddtracker.msu.edu/?model=7&offset=0&zip=48327
Enter your zipcode near the top of the page.
Scroll down the dates in the left hand column(these are for 2024).
The second column from the right within that 2024 group of dates is GDD base 50.
If you have any questions, please ask.
