Herbicide-Free Tree of Heaven Removal: a project for winter!

Tree of Heaven (Ailanthus altissima) is a fast-growing invasive species originating from China and Taiwan; and infamous throughout the Eastern U.S and increasingly so in the Midwest and Western U.S… and for good reason. This trees, ironically enough considering the name, is one of the most aggressive and destructive species I have personally dealt with in the U.S.

History

Tree of Heaven was brought here by a botanical gardener on the East Coast, using it as an “ornamental shade tree” all the way back in 1784. Shortly after, during the gold rush, the second wave of these tree came from the West; in California around the mid-1800s. At this time the gold rush was booming and the railroad was rapidly expanding; its construction fueled by borderline slave workers from Ireland and Asia. As far as we know, some of these railway workers brought Tree of Heaven in some form to use for medicine; from which it quickly self-propogated and spread.

The Problem

Tree of Heaven is extremely problematic across many fronts, but the biggest lies in two things: The underground root system they develop and the way we are taught to kill them. When larger trees are cut down (both part-way up the tree and when fully cut) the root system excretes a series of toxic chemicals that kill all other nearby plants- I have heard multiple reports of grass patches “turning black” after cutting Tree of Heaven throughout the SouthEast. But this is just the beginning :D After Tree of Heaven is cut down, it sends out aggressive new tree starts from those root systems; bringing literal hundreds of new shoots every season for one or multiple seasons. Not only that, but the logs or branches from the cut tree can easily reroot themselves months and sometimes even years later if coming into contact with soil. The much bigger problem, however, is how people are taught to kill this tree. The majority of online sources you’ll find instruct to chop the tree down to a stump and then cover it in glyphosate or other pesticides. Those pesticides are absorbed by the tree and “kills” the roots… but as I have personally seen first-hand over and over again this tarely actually kills the tree stand entirely. In fact most of the time the trees and other invasives become more abundant while native trees and plants are killed off by the slow release of those applied chemicals leeching out into the soil.

The Solution

Now I know this all sounds very doom and gloom, but there’s good news! Not only can we get rid of these trees with NO chemicals, but we can actually produce a lot of food by getting rid of them too. A research study undertaken by a tree farm known as “Blue Owl Hollow” undertook a project back in 2010 where they used native Pearl Oyster (Pleurotus ostreatus) mushrooms to inoculate Tree of Heaven strands- with great success! You can see the full study in the link at the bottom of this page, but for this blogpost I’ll be sticking with what I’ve personally experimented with. Late Fall to late winter is the best time for starting this project; where the trees are more dormant and less prone to suckering. Start by getting a series of Pearl Oyster Mushroom (Pleurotus ostreatus) plugs. These are wooden dowels (basically small wooden pegs) that have been inoculated with the mushroom spores. After buying the spores, begin by cutting the Tree of Heaven trunk down to around 2-4 ft off the ground. Cut the resulting logs into 3-4 foot pieces and prune off any smaller branches; leave the logs off to the side for later. The smaller branches can be chipped and left in a pile to age for a couple of years or simply be piled up and left to rot. Next, drill a series of holes every 3-4 inches down the length of the remaining tree trunk. The size of the holes depends on the size of the dowels you bought. Do this 4 times over the whole length of the remaining stump. Do the same thing with all of those logs you cut up; and stack them in squares linking log style nearby or where desired. These will eventually give rise to mushrooms as well. The tree will still send out new shoots until around mid-late summer so be prepared to do some light hand pulling when Spring starts; but be patient. They will stop after a couple of months. The timing of when the mushrooms begin to actually spawn, well, actual mushrooms, depends on your unique climate, the tree itself, and various other factors- but within somewhere between 6 months to 3 years all the trees inoculated with mushrooms will begin to produce fully edible, native oyster mushrooms for your enjoyment. And 3 years is in extreme conditions; it’s much more often within a year or so. All while killing off the tree’s root systems and preventing it from spreading.

I’d recommend planting some native shrubs and ground covers at the site where the trees are removed to heal & nurture the resulting soil. I’ll make a list at the bottom of this post on which ones work best after experimenting more.

Extra Notes

A link to that Blue Owl Hollow project: https://projects.sare.org/project-reports/fnc07-670/

Going back to glyphosate and chemicals for treating inasive plants, this is a huge part of why I wrote this post in the first place: to provide an option that won’t kill the soil and the life around you. I cannot stress this enough: whether it’s Tree of Heaven or any other “problem”, NEVER. I repeat, NEVER. Use chemicals or pesticides when stewarding land. It’s irresponsible, destructive, and has no benefit except making the task “go faster”. Do not use them if you care about your soil or your wildlife.

Native Plants to Follow the Death of The Tree

Non-Edible:

•Eastern Redbud Tree (Cercis canadensis)- It fixates nitrogen into the soil through its roots and shows off captivating pink flowers.

Throu

•

Edible:

•American Groundnut or Hopniss (Apios americana)- a vining species with edible tubers AND bean pods. It also fixates nitrogen into the soil.

•Honey Locust Tree (Gleditsia triacanthos)- a tree with edible pods rich in carbohydrates that grows quickly and can be used for carpentry projects or as biomass to add back to the soil. It also fixates nitrogen into the soil.