Hello,

Sorry you didn’t find good information at your extension office.

This information is from an earlier question similar to yours:

“( Best practice is) removing the tree-of-heaven at least 30 days after fall application of herbicide. Cutting the tree alive in early spring and treating the stump is the second best option. Reserves are lowest in the tree at this time, so there will be reduced sprouting compared with cutting the tree in the summer. However, it will still result in considerable root sprouting that can be reduced by waiting until the fall and following your arborist’s recommendation. Either method may be used successfully, and both will require following up to control root and stump sprouting.

For more information:

https://plant-pest-advisory.rutgers.edu/tree-of-heaven-best-herbicide-treatment-and-removal-timing/

When looking for research based information, stay with University Extension sources(.edu) , and non-profit (.org) associations dedicated to conservancy, ecology, etc., such as bulletins and videos published by these groups.They are vetted by professional horticulturalists and use proven methods.

Here are some references for you-

https://mipncontroldatabase.wisc.edu/search?name=tree-of-heaven&season=68

https://extension.psu.edu/tree-of-heaven-control-strategies

https://extension.purdue.edu/extmedia/FNR/FNR-633-W.pdf

To find a certified arborist, one who has been trained and passed certification testing, search by zip code here—

www.treesaregood.org

If you have questions and want to speak to a trained Master Gardener volunteer, call the MSU Extension Garden Hotline Mon, Wed., or Fri. From 9am to Noon. Not all are invasive plant experts, but they will know how to find the contacts and answers you need. <personal data hidden>.

You may also reply here with follow-up questions about tree-of-heaven.