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Attempts to manage invasive hardy kiwi varies depending on the amount of kiwi, the extent and area of kiwi coverage, and surrounding areas.

Small Patch of Hardy Kiwi

Large patch of hardy kiwi

Hardy kiwi pulling trees down

 

 

Once kiwi is present, it is often hard to control. Its identification can be difficult as it resembles some other vines such as grapevine, oriental bittersweet, and even the native American bittersweet. The suspected kiwi should be evaluated to ensure that it is not a native species and is indeed an invasive.

After positive identification, management becomes the main question. The first step in managing an invasive species is developing a map of how much area is covered by the invasive species.

Kennedy Park Map

GIS Mapping of Invasive Hardy Kiwi in Kennedy Park, Lenox, Massachusetts. Photo courtesy of NHESP

There are three methods of management: eradication, controlling the species, and isolating the species.

Eradication is most effective with early detection and/or when small areas are compromised. It usually involves hand pulling and close monitoring for a few years to ensure that all the invasive was removed and not regrowing. If the area is covered with more mature or dominant invasives, then sometimes herbicide is used to kill the plants. Again, careful monitoring for several years afterward is essential and retreatment is often necessary.

BEAT only uses hand pulling and cutting. We do not use herbicides.

Hand Pulling

Volunteers hand-pulling invasive hardy kiwi in a wooded area before it has become dominant.

With many invasives, eradication is the best case scenario but often, eradication is not possible due to seeds surviving or being dispersed by animals and therefore is often not the immediate goal for organizations. However, awareness of hardy kiwi invading the woods of the northeast may have been started early enough that eradication might be possible.

Controlling invasive hardy kiwi at any site, starts with determining how extensively it has spread. The teams usually do an evaluation of the area and decide how to go about managing the problem. The best option is to use hand pulling whenever possible and when necessary, use minimal, targeted herbicides that only effect the invasive plants and not native species. After this is done, the area is monitored and treated yearly until a better option for management develops, funding and resources run out, or until it is decided that controlling the area is no longer a practical option (Massachusetts Division of Fish and Wildlife Service, Massachusetts Audubon, & Town of Lenox, 2015).

Foliar Spray

Foliar application of herbicides like the above picture of herbicide being applied to Japanese Knotweed, is just one method of management available for controlling hardy kiwi. Photo courtesy of Japanese Knotweed Eradication.

 

The last option of isolation is usually reserved for the worst scenarios or in rare, important habitat. This is when an invasive species is too extreme to manage effectively and the costs and resources required to control it are beyond feasible. It is also used for scenarios where the invasive is overtaking land that is viewed as rare and vital such as wetlands or habitat known to include rare and endangered species (Massachusetts Audubon. 2017). At this point, organizations step in to isolate the invasive and eliminate it in only small doses where the habitat is most prevalent. This method is not ideal but sometimes it is the best option for areas due to the amount of time they were left with no management.

 

In the Berkshires, our current goal is to eradicate invasive hardy kiwi altogether.

 

Invasive kiwi can grow more than 20 feet in a single year and can grow at least 100 feet up trees smothering them. As trees die and fall, the kiwi reaches out to the next trees forming amphitheaters of nothing but kiwi. In Kennedy Park in Lenox, hardy kiwi covers about 85 acres as a monoculture – completely smothering all native habitat.

Measuring 10 months of kiwi vine growth: 18+ feet

 

The photo to the left shows BEAT measuring two “searching” shoots of hardy kiwi. The 2.25″ diameter piece of vine at the bottom of the photo was part of a vine that was cut May 14, 2016. When we came back in March 2017, the vine that was still attached to its roots in the ground, had put out 5 “searching” shoots, two of which had bridged the 6 foot gap from the vine on the ground to the dead dangling vines up in the trees. the two “searching” shoots extend from the cut vine in the foreground of the photo all the way to Elia holding the other end of the measuring tape next to the car.

 

 

 

This is why citizen awareness for early detection is necessary. This plant needs to stop being grown in the Northeast where it is already an invasive species in the Berkshires of Massachusetts, western Connecticut, parts of New York and New Jersey. It also has the potential to continue spreading throughout the Northeast and will contribute to the loss of forest habitat for native vegetation and wildlife (Griffen, 2015). The sooner the public takes action to prevent the spread of kiwi, the sooner we can begin recovery efforts to restore the natural communities of the Northeast United States.

Literature Cited:

Griffen, J. (2015, September 12). Hardy Kiwi: Delicious, Decorative, Destructive. Retrieved March 26, 2017, from http://blog.uvm.edu/fntrlst/2015/09/12/hardy-kiwi-delicious-decorative-destructive/#_ftn2

Massachusetts Audubon. (2017). Hardy Kiwi. Retrieved March 26, 2017, from http://www.massaudubon.org/learn/nature-wildlife/invasive-plants/hardy-kiwi

Massachusetts Division of Fish and Wildlife Service, Massachusetts Audubon, & Town of Lenox. (2015, Fall). Hardy Kiwi Removal in Kennedy Park. Retrieved March 26, 2017, from http://www.mass.gov/eea/agencies/dfg/dfw/wildlife-habitat-conservation/miller-case-studies-for-successful-management-on-town-and-land-trust-lands.pdf

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