Fall Weed Control Season Has Arrived!

As weeds prepare themselves for their winter dormancy, they are particularly vulnerable to any and all attacks made against them. Whether you prefer chemical, manual, or cultural methods, now is the ideal time to treat those weeds and get the upper hand!

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Yellow archangel, field bindweed, and English ivy (picture in order above) are all renowned as “nearly impossible to kill” weeds and can be particularly aggravating to urban gardeners and homeowners. Not only are they incredibly aggressive in the home landscape, but they are a real threat to Washington’s natural areas and forests when they escape the backyard.

Yellow archangel effectively crowds out important native plants in the forest understory. Field bindweed is sure to drive your neighbor crazy when it creeps under the fence, but it also strangles nearly every plant it comes in contact with. English ivy can invade a tree’s canopy, shading out its host and making it “top heavy” which increases the likelihood that strong winds snap the top of the tree clean off.

English ivy is even recognized by many insurance companies as a potential threat to homes and structures and may result in the denial of coverage for some homeowners.

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A fall application of a broadleaf herbicide such as BioAdvanced Brush Killer, or Ortho Weed B Gon can be used very effectively in the home and garden landscape to get a systematic kill that is from the inside-out. These selective herbicides only cause damage to broad leafed plants, so grasses will not be harmed. If grasses are of no concern, a non-selective herbicide that contains glyphosate, such as RoundUp, will cause damage to any vegetation that it is applied to. When used in accordance with the label, herbicides are both safe and effective for weed control in the home and garden environment.

Manual control of weeds is also very effective when done in the fall. Many biennial weeds such as tansy ragwort will start their life cycle in the fall, so hand-pulling the young plant, or "rosette", now will save you the time and trouble in the summer. For the yellow archangel, the field bindweed, and English ivy, manual removal requires more patience and perseverance , but it is possible. When tackling these tenacious perennial weeds, removing as much as the root as you can is beneficial. Within weeks of hand pulling the vegetation, new shoots will appear. Continue pulling these shoots every couple of weeks and eventually the carbohydrate reserves will be depleted and the plant will not survive.

When using manual methods to control English ivy that has taken over a mature tree, use the 3x3x3 method. Approximately 3 feet up the tree trunk, cut every ivy stem around the entire trunk. Remove as much of the ivy vegetation as possible from this 3 foot section of the tree’s trunk and what vegetation may be growing on the ground around the base. Once the vegetation has been removed, apply a landscape fabric and/or mulch around the base of the tree that extends 3 feet out from the base, and is at least 3 inches deep to prevent sunlight from reaching the soil. Remove new sprouts or vines as they appear. With time, the ivy that remains on the tree should begin to wilt and die back. There is no need to remove this dead ivy from the trunk or canopy as this will eventually deteriorate.

Cultural weed control methods include basic “good house keeping” and maintenance chores. Applying soil amendments will favor desirable vegetation, giving them the competitive advantage against weeds. Seeding wildflowers and grasses is best done in fall and will go a long way toward occupying otherwise “empty” space where weeds would quickly fill in. Refreshing mulches will also help in the fight against weeds.

Ideally, a well thought out weed management plan would incorporate many, if not all of the methods discussed. Lewis County Noxious Weed Control supports and promotes Integrated Pest Management (IPM) as the best management practice for good land stewardship. We are happy to work with all Lewis County residents and landowners to identify how best to control invasive and noxious weeds on their property. If you need help controlling noxious weeds on your property, or if you have any other weed related questions, please get in touch with Lewis County Noxious Weed Control at #(360) 740-1218 / (360) 740-1215, or visit us on the web https://lewiscountywa.gov/departments/weed-control/

Posted: September 17, 2021