Herbicide use near established trees?

Asked March 12, 2018, 12:19 PM EDT

Hello, I've read on this extension site that Roundup and/or Crossbow (or a mix) can be used to control blackberries and poison oak. I have plenty of both and routinely go at them manually, in a part of my yard with plenty of established trees (mostly Doug fir, with a few big leaf maple, white oak, madrone, and native cherry). There are some gaps in the canopy that have allowed the blackberry to thrive the last couple years. Can I use the herbicides sparingly without threatening the trees? I've been trying to avoid using the stuff entirely, but the blackberries are starting to get away from me and turn a significant portion of my property into a thicket. I'm wondering if the herbicides are safe to use in any amount near established trees. I'm hoping to knock the blackberry back and establish other plants to keep the area more shaded, and it would be a shame to mistakenly kill a tree. Thanks!

Benton County Oregon weed control herbicides

1 Response


Yes, it is quite reasonable to safely use herbicides in the situation you describe. I must point out that Crossbow is not registered for use in forestry, but there are several other effective and legal options.

I would need to talk to you about the situation before giving you any specific guidance. But here is a link to the first of a series of short articles I wrote that gives some general guidance for using herbicides in a situation like yours. http://blogs.oregonstate.edu/treetopics/2013/08/15/weed-control-and-herbicide-basics/ Another link at the bottom of the article will lead you to the next.

We should speak after you have read through this. My number is 541 766 3554 and my email is brad.w-r@oregonstate.edu if you want to leave me a message with a name and phone number, and I can try calling you. Be sure to reference this, so I know we have already communicated.