Conflicting advice regarding ivy-on-tree control
Today's Garden Q & A column in the Baltimore Sun, 26 January 2020, "advised avoiding application of weed killers on trunks or under trees". Past columns about controlling ivy on trees recommended applying glyphosate (AKA RoundUp) after cutting ivy at the base of a tree. This seems to be conflicting advice. Please, explain further how to safely control ivy around trees.
Baltimore County Maryland
Hello. We're sorry to hear that this piece of advice caused some confusion. With regard to using herbicides to control invasive vines on or growing around trees: first, we recommend manually removing (pulling up) plants from the ground and cutting vines that are growing up on a tree. Then, apply herbicide directly to the freshly cut vine stems, avoiding contact with the tree trunk or roots.
For example, to eradicate English ivy that is growing on trees cut the vine off at the base of the tree and paint the newly cut end of the vine with a systemic herbicide (containing glyphosate or triclopyr) at high strength. Read the product instructions pertaining to tough weeds. Do not let the herbicide get directly on the tree. For English ivy groundcover, pull up as much as you can, dig out the roots as well as you can, and repeat until it no longer re-sprouts; or treat the re-growth with an herbicide (applying it directly to the foliage, not the ground).
I hope that helps. Let us know if you have any further questions.