By Judy Kunz, Colorado Master Gardener

Tree of Heaven – The Time Is Now

Those who have been plagued by the invasive Tree of Heaven (Ailanthus altissima) and have attempted to eradicate it know how seemingly impossible this task is. Chopping it off just encourages more growth, with additional sprouts coming up from the extensive root system. Trying to dig it up can lead to a deep webbing of underground roots. Hand pulling young seedlings can be frequently futile if the entire root is not removed because root fragments can continue to sprout into new plants. This invasive plant seems to pop up just about anywhere, actually preferring neglected areas and thriving under hot, dry weather conditions. In addition, it sends out runners that parent more trees; its roots tend to kill surrounding vegetation; and mature female trees produce seeds in almost unbelievable quantities.

The good news is that mid to late summer is the ideal time to destroy this invader. During this time of year, the tree is actively moving the products of photosynthesis to the root system, so the most effective treatment is to target roots with systemic herbicides containing triclopyr or glyphosate. These herbicides are recommended because they have very little residual presence in the surrounding soil. Waiting to remove the tree at least 30 days after herbicide application will allow it to penetrate the roots and do its job. Because of the expansive root system, follow up treatments may be necessary in the fall for two to three years to completely eradicate it.

See this link for detailed information on Tree of Heaven eradication: https://plant-pest-advisory.rutgers.edu/tree-of-heaven-best-herbicide-treatment-and-removal-timing/