The Berks-Mont News (

Weed Warriors: Dedicated to removing invasive plants

By Richard Gardner, Columnist

Tuesday, June 4, 2013

Weed Warriors are people who dedicate themselves to removing non-native invasive plants from private land, parks, trails and wherever the problems are found. They spend their weekends pulling and bagging garlic mustard, mile-a-minute, multiflora rose, wavy leaf basket grass, Japanese stilt grass, Japanese knotweed, Japanese honeysuckle, wineberry and similar. One of the members of my grad committee is Dr. Marc Imlay who is one of the earliest weed warriors. He has taken on parks in the DC area such as Anacostia Park, Greenbelt Park and Paint Branch Park.
Locally, our biggest problems are garlic mustard, Japanese stilt grass, Japanese honeysuckle, Japanese barberry, bush honeysuckles, oriental bittersweet, Russian olive, autumn olive, multiflora rose, wineberry and Tree-of-Heaven. Control of all of these plants except Tree-of-Heaven is to pull the plants out with all the roots if possible before seed set and then bag them. When walking trail, instead of bagging, I often shake the dirt off the roots and hang them from shrubbery or on a rock so they desiccate. Tree-of-Heaven is an important exception. This needs holes 3/8” drilled every 2” around the trunk below the lowest branches and filled with @ 50% glyphosate (RoundUp®). One treatment usually works. Any attempts at pulling out or cutting down this plant will result in clones, even from 2” or 3” tall seedlings.
My greatest concern is mile-a-minute. It is a serious hitchhiker and spreads easily throughout our area. Pull it whenever and wherever it is found or we are in for an awful mess. It has prickles, so be careful. Second to this is Japanese stilt grass which is found all over our trails and appears to be primarily carried on our shoes, socks and other clothing. Fortunately, there is a pathogen that is beginning to kill it.
Multiflora rose and Tree-of-heaven are two more plants beginning to be affected by pathogens. Whenever I walk, I see “witches broom” on multiflora. This is a sign that a mite and its pathogen are beginning to give us hope for its demise. With Tree-of-heaven, I see a wonderful orange, black and white spotted moth, along with its larvae. Along with this are a pathogen and at least one mite which is the probable carrier of the pathogen.
What can we do besides pulling the weeds? When walking trails, check for hitchhiking seeds in socks, on shoes and on clothing, especially after walking through beds of invasives such as Japanese stilt grass and garlic mustard. Brush or wash shoes. Bag any seeds you see and drop them in a trash can at home.
Anyone interested in forming a Weed Warrior group for Berks County, please contact me at and we will start one.
Richard Gardner lives in Upper Bern Twp. His passions are ecology and history because with these we are able to understand our world, our place in it and our future.