Allegheny River Headwaters Watershed Conservation Plan

Allegheny River Headwaters Conservation Plan
Chapter 4. Biological Resources
Japanese knotweed grows from seeds and is able to regenerate from vegetative pieces. It can grow to
over 10 feet in height. The very small, shiny, triangular shaped seeds can be dispersed via wind, water,
fill-dirt, and on the soles of shoes. It is a very durable plant, capable of surviving high temperatures,
droughts, and flooding.
In order to control populations of Japanese knotweed, a combination of mechanical and chemical
treatment techniques must be employed. Single young plants may be pulled by hand if soil conditions and
root development is right. However, to prevent resprouting, all roots and runners need to be removed
from the site. Chemical treatment using glyphosate and tricolopyr herbicides can be applied to freshly cut
stems or foliage (Swearingen, Reshefiloff, Slattery, & Zwicker, 2002).
Japanese honeysuckle
Japanese honeysuckle is a perennial vine that escaped cultivation and invaded natural areas.
Introduced to the U.S. from eastern Asia during the 1800s, it was used to control erosion and as cover and
food for wildlife. Populations of Japanese honeysuckle have been established in Potter County, while no
populations have been reported in McKean County.
It is capable of spreading rapidly due to its vigorous root competition and its ability to twine itself up
trees and shrubs in order to dominate the light source. These activities destroy nearby vegetation and
girdle trees and shrubs. Like evergreens, Japanese honeysuckle is able to continue growing while most
native species are dormant, providing additional opportunities to overtake the native vegetation.
Manual and chemical control methods can be utilized to reduce Japanese honeysuckle populations.
Manual removal of small infestations can be effective when the whole plant, including the root, is
removed. Sites undergoing manual treatment need frequent monitoring and removal of new outcrops.
Creeping vines need to be cut and removed in order to protect trees and shrubs from being girdled. In
order to remove larger patches of honeysuckle, hold the vine mass above the ground with a rake while
cutting the stem as close to the ground as possible. Mowing is also applicable, but requires two
treatments—mid July and mid September. Combining mowing with chemical treatment increases the
effectiveness of treatment. Chemical treatment is most effective when desirable native species are
dormant and Japanese honeysuckle continues growing. Apply the herbicide to healthy, green leaves
during temperatures in which the honeysuckle continues to grow. This will control the honeysuckle
population with reduced risk to native species.
Mile-A-Minute
Initially introduced to the U.S. in the late 1800s, mile-a-minute is native to eastern Asia and the
Philippines. It is an herbaceous, annual, trailing vine that contains recurved barbs on the stems and leaf
blades that can self pollinate. The leaves, light green in color, are shaped like triangles. Ocreae—cup
shaped leaf structures that surround the stem and nodes—are where the flowers and fruits emerge. The
deep blue fruits are located in terminal clusters, with each berry-like fruit containing a single glossy black
or reddish-black seed known as an achene. Mile-a-minute is a prolific seeder, producing many seeds from
a single plant. The seeds are durable, remaining viable in soil up to six years, with staggered germination
and buoyancy in water for seven to nine days (Okay, Goldstein, & Swearingen, 2010).
Mile-a-minute invades open fields, forest edges, roadsides, ditches, streambanks, and uncultivated
fields. Its rapid growth allows it to cover existing vegetation and restricts light availability, potentially
killing plants below. Dense mats of mile-a-minute can restrict the establishment of new vegetation. It is
often found in extremely wet soils with poor soil structure and prefers sunlight, but can tolerate shade.
Populations of mile-a-minute have established in Potter County. A variety of control methods, such
as biological, chemical, and mechanical practices, can be implemented to reduce or eradicate mile-a-
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