Help identifying a weed/tree on my property

Asked September 13, 2017, 1:19 PM EDT

Hello! I am having a difficult time identifying this weed/tree through the identifier and was wondering if you would be able to identify it? I'm located in Portland. It is growing in my yard near the foundation of my house. Thought it was a tree but an inspector let me know it was actually a giant weed and to take it out as the roots could crack the foundation. Didn't catch the name of it and am now curious as it's grown about 10 ft tall now. Here are some photos. The main stalk had around 6 larger stalks with giant leaves. Thank you in advance!

Multnomah County Oregon

3 Responses

Does this plant have an unpleasant odor? It looks similar to Tree of Heaven, but the leaves of that species tend to be narrower and pointed. It may be an ash tree, but the bark doesn't look right. Even if it isn't this https://www.nwcb.wa.gov/weeds/tree-of-heaven or http://nativeplantspnw.com/oregon-ash-fraxinus-latifolia/ if it's growing aggressively and you don't want it there, then it's best to cut it down as close to the ground as possible. If you are vigilant and continue to cut it back so there are no leaves, the plant will eventually die. (This may take several years.) I would be especially concerned if it is affecting your home's foundation.

Hi Sara,
thanks for your response! I don't believe it is either a tree of heaven or an ash tree. The centers when the stalk is cut is fibrous and does not have rings. We have cut it back and are digging near the roots which are quite large - not sure how long they are. If we cut it back not allowing the leaves to grow would the root system also grow? we are mostly concerned the roots will crack the foundation and are hesitant to use any sort of pesticide.
Thank you !

Most plants store energy in the roots and stems as they go dormant for winter. Those stores are used in the spring to create leaves which then use photosynthesis to help the plant grow (more roots, more stems/branches, leaves, etc.) If you deprive the plant of its ability to photosynthesize, it has to use all reserves to create leaves. Eventually the reserves are used up and the plant can't survive.

Although you may want to limit your use of chemicals, there are some legitimate circumstances. For a plant like this, use of a glyphosate may be warranted. I looked for research on other controls and this one popped up regarding vinegar https://extension.umd.edu//sites/extension.umd.edu/files/_docs/programs/ipmnet/Vinegar-AnAlternative.... Since you have a large, fibrous plant, it's doubtful acetic acid/vinegar will be effective. An alternative is boiling water but that will only affect the surface plant and will not go down to the roots.

In this case, I would 'paint' the leaves with concentrated glyphosate today (if you can) so the compound can get down into the plant and roots (it's expected to start raining this weekend so sooner is better.) Once you see the leaves shrivel, cut the plant back and then paint the stems. When using any product, please be sure to read the directions and safety precautions.

Monitor the plant weekly and remove any/all growth as you want to starve the plant.