For all invasive elimination, expect to continue control efforts for 2-5 years, or even longer, to deplete the seed bank.
Plants should be bagged in plastic and disposed of in the trash to prevent seed dispersal or re-rooting.
Glysophate is the best option as it is a non-selective herbicide, It effective, has no soil activity and has low toxicity to nontarget organisms. Selective broadleaf herbicides such as triclopyr can be used but are less effective, however does not harm grasses.
If the treatment is required near a waterway, there is an aquatic glysophate option available (avoid spraying directly into the water)
Air temperature must be at least 50 degrees for treatments
As with all invasive plant eradication, long term succession planning is ideal to replace with stands of native species.
If removing by hand, the underground tubers must all be dug up and bagged.
The timing of this treatment is the most crucial and difficult because the treatment window is very short in early spring. Glysophate is the most effective product, however triclopyr is often used as celendine is often found growing within lawns and it will not harm grasses.
Ideally, two treatments are applied. Once in the foliar stage only, prior to blossom, and once mid blossom.
Do not mow celendine as it can promote the spread of it.
After two rounds of glysophate, seed the areas to outcompete, but continue to monitor the area and plan to treat the following spring with Triclopyr.
If only treating with Triclopyr, don’t attempt seeding until after 2 years of treatments.
The primary objective in controlling Japanese knotweed is eliminating the rhizome system.
There are two phases of knotweed management: initial control and maintenance. The control phase for knotweed takes at least two seasons and consists of either two applications of herbicide or a cutting with a follow up of herbicide. Late season application of herbicide in the control phase is especially effective. After initial control efforts have nearly eliminated the knotweed, you will need to periodically monitor the site and treat any new growth to prevent reinfestation.
Cut and treat method is best. Cut down to the ground in June and wait 7-8 weeks for it to regrow to treat with Glysophate Set up two treatments, spaces 2-4 weeks apart.
If no cut method, can use herbicide only. Set up 2-3 treatments July-September. Can not spray overhead.
Swallow-wort can be managed manually, but only if removal is extremely thorough. Plants should be dug up so that the root crown and rhizome is removed before seeds mature.
Mowing can be effective, but only if done every year prior to seed dispersal. Note: this will not stop the spread through rhizomes.
The cut and treat method is best. Cut or mow in late June/Early July. Apply glysophate after the plant flowers in late summer ( mid- to late-August) to plants that have been mowed or trimmed in early July may provides the best results. The mowing of plants in early July also ensures that no viable seeds are produced prior to application of the herbicides.
Garlic mustard has a taproot, and unlike some invasive perennials, it does not regenerate from root fragments. Therefore, this is one of the few invasive plant species that can be more easily controlled manually by pulling. Pulling that completely remove shoot tissue will prevent regrowth. Plants should be pulled before the seed stage
Prioritize pulling or cutting before seed set, ideally in the spring or early summer
Hand pull when young
Treating with glysophate is a more targeted approach and can be done anytime during the year prior to seed stage.
Here is a list of other invasive plants that, if found on your property, consider immediate removal:
Common Buckthorn
Japanese Barberry
Bush Honeysuckle
Japanese Stilt grass
Multiflora Rose
Tree-of-Heaven
Giant Hogweed
Common Reed
Norway Maple
Burning Bush
Black Locust
Bradford Pear
Full List: https://extapps.dec.ny.gov/docs/lands_forests_pdf/isprohibitedplants2.pdf
