How to Control Bishop's Weed

Bishop's weed colonizes quickly and out-competes native flora.

Bishop's weed, Aegopodium podagraria, also commonly known as goutweed or snow-on-the-mountain, is an aggressively growing, invasive plant that is difficult to control. It grows throughout most of the United States and tolerates a wide range of soil conditions and sun exposure. It spreads underground by rhizomes, making it resilient to attempts to control it. If it is successfully eradicated it in one area, it is likely to emerge in another. There are a few different control methods available, and a combination of all may be required for successful eradication.

Things You'll Need

• Shovel
• Wheelbarrow
• Black plastic sheet or tarp
• Nonselective broadleaf weed killer
• Non-ionic surfactant such as a spreader-sticker
• Pump-sprayer
• Safety goggles
• Chemical-resistant gloves

Instructions

Physical Control

1. 

   For smaller patches of bishop's weed, control can be as simple as digging them out.

   Dig out as much of the bishop's weed as possible. Get the entire root system where possible so that it does not grow back.

2. Place dug-up bishop's weed in a wheelbarrow or other area where it can sufficiently dry out and not re-establish itself. Dispose of dried foliage and rhizomes of bishop's weed where they cannot take root elsewhere.

3. Cover the area where the bishop's weed was growing with black plastic or tarp. This will exclude the sun for the remainder of the bishop's weed colony and their rhizomes so that photosynthesis is impeded. A non-porous covering will also prevent them from receiving rain water. This method can also be tried without digging bishop's weed out first, but that is not practical for larger patches.

Chemical Control

1. 

   Pesticide labels should list the required protective gear to use.

   Mix the nonselective broadleaf herbicide in a pump sprayer according to label directions. Wear all required personal protective equipment including gloves and safety goggles while handling herbicides.

2. Add the spreader-sticker to the mix according to label directions. Bishop's weed has a tough, waxy coating. The spreader-sticker helps to make the herbicide solution more sticky. When the spray is applied to the weed, it clings and does not just roll off of the plant's surface.

3. Repeat applications as needed. Controlling bishop's weed even with chemical herbicides will require diligent monitoring and re-application of the the herbicide.

Tips & Warnings

• Bishop's weed is more susceptible to control methods in the spring before it is actively growing for the season. Control measures are best started at the first signs of growth for the year.

• Expect to make spring, summer and fall applications of herbicide to control bishop's weed.

• Always follow the directions on any pesticide label. Federal and state laws require strict adherence to the procedures for pesticide use as prescribed by the manufacturer.

References

• University of Illinois Extension; Bishop's Weed, Goutweed Aegopodium Podagraria; 2011
• The Ohio State University; Aegopodium Podagraria 'Variegatum'
• National Park Service; Goutweed; Steve Garske, et al.; 2009
• North Dakota State University Extension; Questions on: Miscellaneous; Ron Smith