The removal of buckthorn plants ½” and over in diameter is best performed by the cut and treat. The plants are cut at the base as low to the ground as possible and chemically treated with a herbicide. The best time of year to use herbicide treatment is after the leaf out stage, (usually June) when energy created is traveling to the roots. The Herbicide is absorbed into the plants crown and roots to kill new growth. Herbicide is often mixed with a dye to note treated areas.
Using herbicides for treating
Note: Check local laws about applying herbicides, you may have to be certified to apply chemicals on some private and public areas. When using herbicides always read the complete product label plus follow all product manufacturers’ usage labels and safety instructions.
Don’t cut buckthorn close to the ground without immediately treating the freshly cut stump. Vigorous re-sprouting will occur without treatment, creating many new buckthorn stems. Instead of cutting and treating one original plant stem, many new sprouts will each require cutting and treatment. If re-sprouting occurs after a cut was made, make a single cut below the re-sprouts, and treat a single freshly cut stump.
Don’t use a weed wrench tool or a shovel to dig out larger buckthorns. This practice is discouraged for several reasons. The disturbing of soil is susceptible to erosion, especially on sloped areas. Also, disturbing the soil provides a perfect environment for buckthorn, garlic mustard and other invasive plant seeds to germinate. Wrenching and digging are more time consuming than the cut-stump method. The small buckthorn seedlings may be hand-pulled when soil disruption is minimal.
An important step in removal of buckthorn plants in an area is to target and prioritize. The plants that need to be removed first are the female buckthorn, the plants that produce berries or fruits. The berries or fruits will contain up to 4 seeds in each berry. The seeds are the primary means of the spreading of buckthorn. The seeds can be transported long distances by birds and small mammals. By removing plants with berries or fruits first, future seed production is stopped. This step is critical in controlling buckthorn.
The second priority for removal is the buckthorn plants that surround valued native plants. The cut and treat method of plant removal can be used. Native tree seedlings, shrubs and wildflowers are of high value to restore areas to there native habitat.
The third priority is to remove buckthorn by starting with the largest plants. The larger the buckthorn means the more shade that will cut off sunlight to native plants. The base cut and treat method does work on large plants, but sometimes a two-step approach is needed.
1. Cut buckthorn plants about waist height. Remove the cut plants from the area. Removal of the cut buckthorn plants can be very difficult in densely populated areas of buckthorn, due to the plant canopies intertwining each other. If plants are removed from the control area special care needs to be taken with the plant that has berries or fruits, because the buckthorn plants produce berries when they reach maturity. Each berry will contain up to 4 seeds which will remain viable in the soil for approximately 5 to 7 years. If the cut buckthorn bush is moved, the berries can fall off stems, which could create new areas for the plant’s seeds to grow. By chipping the plants at the removal site, seeds from the plants are not relocated. Also, special care is needed if the wood chips from buckthorn plants are used in other areas, as the seeds may germinate in areas where the plants may never have been before.
2. Return to the site at later date and cut the remaining portion of the buckthorn close to the ground. Treat the freshly cut stumps immediately with a herbicide. The cut stems can be left in the area to decompose or be removed from the site. The stems make good firewood when dry.
Herbicides are useful tools an effective option for buckthorn control if used correctly. The effects of herbicides on buckthorn plants depend on the growing stage. When the plants are in leaf development the plants' energy travels upward, which will decrease herbicide efficiency when used treating fresh cut stumps and cuts at base of stems or trunk (basal cuts). After all the leaves come out (leaf out stage) and blooming of the flowers, energy travels to the roots which is an effective method for treating stumps or basal cuts.
The following are some common name herbicide products with the Trade names used to control buckthorn stumps and basal cuts.
Glyphosate with a concentration above 20% (Roundup®, Touchdown®) (Bonide KleenUp ® Concentrate)
Triclopyr (Garlon4™) (Bonide Brush Killer BK-32 RTU)
One Product that works will of buckthorn seedlings and young plants is Bonide Weed Beater® Ultra.
The buckthorn plants are very difficult to control and will need to be monitored for many years. One of the main reasons Buckthorn is difficult to control is the seeds lay dormant and viable in the soil for 5 to 7 years. It is also important to locate and control seedlings after initial control effects are started. If no follow up is performed Buckthorn will come back.
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