Allegheny River Headwaters Watershed Conservation Plan

Allegheny River Headwaters Conservation Plan
Chapter 4. Biological Resources
With few natural enemies, Japanese honeysuckle is able to flourish, rapidly out-competing native
plants by vigorous root competition and blocking sunlight. It also has the capability to kill young trees
and shrubs when its vines tightly twist around the stems and trunks, cutting off the flow of water and
nutrients.
In order to control the spread of Japanese honeysuckle, manual and chemical treatments can be
effective. The methods used will depend on the location and size of the infestation. For small infestations,
repeated pulling of the entire vine and root system is effective, although frequent monitoring and
maintenance are needed to prevent reestablishment. Large infestations can be removed by holding the
vine mass off the ground, while cutting the stems as close to the ground as possible. Mowing is also an
effective control practice; however, it requires at least two cuttings per year. Chemical treatment is also an
effective management technique, especially because Japanese honeysuckle continues to photosynthesize
after most native plants are dormant. The herbicide must be used on green, growing plants. It is more
effective when combined with mowing techniques.
Canada Thistle and Bull Thistle
Two non-native species of thistle have established throughout McKean and Potter counties. Thistles
are problematic in crowding native species and reducing crop and forage areas. The plants typically start
growing in disturbed areas, such as ditches and abandoned lands, then spread into open fields and
farmland. Thistles reduce pasture lands, because cattle typically will not graze near an infestation of the
species.
Accidentally introduced through shipments of farm seed in the 1600s, Canada thistle is a creeping,
perennial weed that is difficult to control. It reproduces via seeds and vegetative buds in its root system;
and within two years, one plant can colonize an area three to six feet in diameter and can produce 1,000–
1,500 seeds per flowering shoot. Canada thistle seeds remain viable in soil up to 22 years. Seeds are
dispersed via wind, water, animals, farm equipment, and vehicles. The very extensive root system is able
to grow six to 15 feet deep and spread over 15 feet horizontally. New plants can sprout from vegetative
buds on the roots at anytime.
In order to control the species, the plant needs to be stressed so it is forced to use stored root
nutrients. Control methods need to be repeated, and it takes several years before there are any signs of
success. Mechanical control is ineffective, unless it is conducted at one-month intervals for several
growing seasons and/or it is combined with chemical, biological, or cultural treatment (Beck, 2010).
Bull thistle is a biennial plant—plant with a two-year life cycle—that infests grassy areas, excluding
other herbaceous plants from growing there. Each flower head produces up to 250 seeds, with each plant
producing approximately 4,000 seeds. The seeds are dispersed by wind, and rapidly colonize in disturbed
areas, with flowers typically present from June to October.
Similar to Canada thistle, controlling the spread of bull thistle requires the combined use of
biological, chemical, and manual techniques. During manual treatment, flower heads are removed. If
flower heads are removed before seeds are produced, then the dead plants can be left on site. However, if
the flower heads are removed once seed production has begun, then they should be placed in bags,
removed from the site, and burned.
Cheatgrass
Native to Europe, Asia, and Africa, cheatgrass—an annual winter grass—was accidentally
introduced into the U.S. in 1861 through seed contamination and ship ballast. It bears many finely-haired,
drooping, yellowish-green, bristly spikelets in a loose, much-branched, terminal cluster. Cheatgrass
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