Buckthorn stump treatment
We cleared a 20 foot by 80 foot area of land that was covered with buckthorn by having a crew come in and cut the trees and bushes down. We did this 3 weeks ago and did not treat the stumps. The stumps are about 4-6 inches high. I read that the herbicide should have been applied to the stump within 24 hours of cutting. Can we cut the stump down further and apply herbicide now?
Hennepin County Minnesota
Thank you for the question. You will need to make fresh cuts and treat them with herbicide. Please refer to Minnesota Extension publication for additional details: BUCKTHORN CONTROL by Karen Jeannette https://www.extension.umn.edu/garden/yard-garden/weeds/buckthorn-control/
Excerpt: Stump treatment When controlling large quantities of buckthorn, cutting the stems, then painting or spraying the stumps with the herbicide glyphosate (commonly sold as RoundUp™) is quite effective. You will need to buy a concentrated form containing 25 percent or higher amounts of the active ingredient, glyphosate. Stores may carry concentrated forms containing smaller percentages, so it is important to read the fine print on the label. Farm and landscape supply stores often sell this more highly concentrated glyphosate. The proper time to cut buckthorn and apply glyphosate is when the plant is active or when the leaves are fully expanded and temperatures are above 32° F. This will ensure that the herbicide is taken up by the plant. The herbicide must be applied within 24 hours of cutting, but applying it immediately after cutting is best. In cases where more than a few plants are treated, it is beneficial to add a dye to the herbicide to mark cut stumps and bark you've already sprayed. Laundry blueing works well, is inexpensive, and is available at the grocery store. If you choose to use an herbicide as a means of buckthorn control, always read and follow label directions to prevent danger to yourself (the applicator), and to the environment, and to ensure that the herbicide will work effectively.
Thank you for contacting Extension.