Weed eradication

Asked June 11, 2020, 12:32 PM EDT

Greetings, I live in Eugene and I am being slowly overrun by weeds, especially Shining Geranium, though many others are present as well. We have been hand-pulling plants for weeks, but cannot keep up. Some of the weeds are in large patches, others mixed in around rhododendrons and other trees/plants. I'm looking for a way to eradicate (for good, if possible) the weeds without the immense labor of hand-pulling. Getting stung 8x by Yellowjackets the other day have convinced me that there must be a better way. I'm trying to steer clear of nasty chemicals, but I am open to any alternatives you can suggest. I do have access to a small flamethrower, if that's an option to be explored. Many thanks, John

Lane County Oregon

1 Response

Shiny geranium is truly a challenging weed to deal with. I have past professional experience trying to control it with methods including hand removal, flame weeders and herbicides. Due to its many seeds that are ejected long distances from the plant, it may not always be possible to get rid of once it's established. Here are some suggestions from Extension forester Glenn Ahrens in response to a similar inquiry:

The weed in your photos is shiny geranium (Geranium lucidum), which, along with the often-associated herb Robert (Geranium robertianum) is a class B noxious weed in Oregon

http://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/ShinyGeraniumProfile.pdf

http://www.oregon.gov/oda/shared/Documents/Publications/Weeds/HerbRobertProfile.pdf

While it is important to control these Class B noxious weeds, they are well established in western Oregon and often difficult to control. As with most weeds it is important to take control measures before the plants go to seed. It appears the seeds of shiny geranium may only be viable for several years, so a few years of consistent effort to control these plants before they go to seed can greatly reduce the problem. Shiny geranium plants seed in late June through July so March and April are the ideal times to take corrective action.

Options for controlling shiny geranium depend on the size of your weed infestation, how it is co-mingled with desirable plants, and your own preferences for weed control methods. Small patches can be controlled with hand pulling and digging. Weed suppression with landscape fabric and mulch can work. Herbicides can be quite effective. Ultimately, the long-term solution depends on the combination of initial control followed by replacing the weeds with more desirable plants that can dominate the area and resist future invasion.

Rather than repeat more details here, I refer you to several sources describing specific control options:

The Tualatin Soil and Water Conservation District has good information about dealing with weedy geraniums at http://www.swcd.net/invasive-noxious-weeds/geraniums/

The King County weed program in Washington has good information https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/shiny-geranium.aspx but you should note the noxious weed information specific to Oregon that I cited at the beginning.

Please refer to herbicide labels for site specific control information and refer to the PNW Weed Management Handbook for additional information on herbicide use. http://pnwhandbooks.org/weed/

https://pnwhandbooks.org/weed/problem-weeds/geranium-shiny-geranium-lucidum-herb-robert-geranium-robertianum

Glenn Ahrens Forester, glenn.ahrens@oregonstate.edu Oregon State University Extension Service http://extension.oregonstate.edu/