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Written by: Matt Nespeca
Invasive Species Consultant
cell: 843-833-5250
Overview of the Impacts of Chinese Privet (Ligustrum
sinense):
Chinese privet is a significant threat to native forests and natural
habitats throughout the southeast and eastern US. The impacts from
Chinese privet include:
• Reduction in the aesthetic value of forestland and grasslands
by creating walls of vegetation that block wildlife observation
and recreational use.
• River bottoms, streamside zones and bottomland hardwood
forests are readily taken over by privet, reducing recreational
access and visibility.
• Chinese privet can dominate the shrub layer in forests,
shading out valuable wildlife friendly plants such as forbs and
grasses and desirable hardwood regeneration.
• Chinese privet is shade tolerant, and can establish in shaded
woodland environments, but when disturbance occurs (like logging,
tree removal, ice or wind storms, or road construction), it can
take over the site, and impede the recolonization by desirable native
plants.
• USDA Forest Service research indicates that Chinese privet
infests 5% of all forestland from Virginia to Florida, and the infestation
has doubled in the past two decades
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| Picture 1: No Treatment |
Picture 2: 1 year after treatment,
2.5 pints/acre glyphosate plus
1.25 oz./acre Escort XP plus 1% surfactant.
Treated by mistblower in December
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Chinese Privet Treatment Methods and Strategies
Chinese privet infestations can be controlled using a variety of
methods. Because privet is evergreen, there are many options (both
foliar treatment and individual stem treatment) to control privet
without damaging hardwood regeneration, forbs and grasses. Before
conducting herbicide treatments, carefully read all herbicide labeling
and directions.
In a working forest environment, such as southern pine plantation
management, Chinese privet can be controlled in the course of regular
forest management activities, such as chemical site preparation
and woody release treatments with tank mixes that contain products
like Chopper® or Arsenal® AC. Chinese privet becomes more
of a management problem in more low intensity management situations
and recreational settings, such as bottomland hardwood flats, streamside
management areas, and park areas. Once privet becomes the dominant
plant in bottomlands and streamside areas, any future disturbance
in the overstory will enhance privet spread and cover. Natural regeneration
of more desirable hardwood species such as oaks, hickory and blackgum
will become stressed by privet competition, and the forest will
likely never recover a mature overstory condition. This situation
can be seen along streamsides and in forested wetlands throughout
the Southeast.
Large contiguous stands of Chinese privet can be difficult places
to work, with coverage and selectivity being essential for a successful
treatment. As with many invasive plant problems, even a successful
treatment will require follow-up treatment and monitoring. There
are professional applicators and specialists that focus on selective
invasive plant control work, so always consider the value of professional
application when attempting to control large stands of privet.
Manual Control
Manual control for small seedling and saplings is an option
for small privet infestations. Young Chinese privet seedlings and
saplings can readily be pulled out of the ground. Because privet
can grow in an extremely dense condition (sometimes more than 40,000
stems per acre), manual control and root pulling is rarely the sole
method of control for landowners and land managers, unless it is
a very small area of seedling and sapling sized privet.
Foliar Treatments
The biggest opportunity to control vast stands of Chinese
privet is with broadcast foliar treatments in the dormant season.
Beginning several years ago, researchers at US Forest Service, University
of Georgia , Clemson University, and elsewhere began to look at
dormant season foliar treatments. Because of the safety of these
treatments in mature hardwoods, with little potential damage to
desirable vegetation, operational treatments on privet in the dormant
season are becoming a standard practice in ecological restoration.
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In recent years, demonstrations have been conducted
to determine the feasibility of backpack mistblower applications
on Chinese privet in the dormant season, and the results provide
excellent coverage, control and safety for non-target species.
Whether utilizing foliar treatments by backpack, mistblower or vehicle
mounted sprayers, treatments should be conducted in the dormant
season after all desirable hardwoods, grasses and forbs have dropped
leaf or entered dormancy. Privet is evergreen, but treatments should
not be attempted when the plants are extremely stressed by prolonged
freezing temperatures or drought. Applications appear to work best
when daytime and nighttime temperatures are staying above freezing.
The products that work best for selective control of Chinese privet
in hardwoods in the dormant season include foliar treatments of
glyphosate (such as Accord® XRT II), Escort® XP, and combinations
of the two products. Both glyphosate formulations and Escort XP
are labeled for wetland environments, but aquatic glyphosate formulations
(such as Rodeo®) should be used alone when standing water is
present in the treatment area. Also, Accord XRT II or Rodeo should
be used alone when a forest stand contains redbud, winged elm, and
other sensitive hardwoods that may be damaged by Escort XP. The
rate of Accord XRT II and Escort XP necessary for excellent control
of Chinese privet will depend on the expected water volume of the
application and the density of the privet infestation. In any case,
full coverage and wetting of the privet foliage is necessary for
good control. Also, additional surfactants may provide enhanced
uptake and activity, depending on the product formulations that
are used.
Individual Stem Treatment
While dormant season foliar treatments provide selectivity
due to the timing of the treatment, individual stem treatments such
as hack-and-squirt, basal bark and cut stem methods provide very
specific selectivity due to placement on the target stems. All of
these individual stem treatment methods provide good control Chinese
privet, and are commonly used as stand alone methods in sparse infestations,
and in combination with foliar methods. These individual stem treatment
methods can be done all year long, with the greatest ease of application
being in late fall and winter. It has been suggested that late spring/early
summer is not a good time to utilize individual stem treatments,
due to sap rise, and a reduced level of downward translocation in
the stem during that time of year.
Hack-and-Squirt
Hack-and-squirt treatment involves making hacks with a
hatchet or machete around the stem near ground level, and spraying
a small amount of concentrate herbicide solution into the hack marks.
Generally, one hack is made for every 2 inches in diameter for a
single stem. Products like Garlon® 3A and Accord XRT II in 50%
solutions with water are effective at controlling privet when utilizing
hack-and-squirt treatments.
Cut Stem
Cut stem treatment involves cutting a stem at or near ground
level, and spraying an herbicide mixture directly onto the cut stem.
This can prevent resprouting, and provide control of Chinese privet.
Products that are effective at cut stem treatment include Pathfinder®
II, Garlon 3A, and Accord XRT II.
Basal Bark Treatment
Basal bark treatment involves the use of products like
Garlon® 4 Ultra, which is mixed with an oil carrier, and is
sprayed around the circumference of the Chinese privet stems so
that the treatment encircles the stem. Treatment of approximately
18 inches of stem length near ground level should be sufficient
to top-kill the privet, and it will translocate herbicide downward
as well. Pathfinder II is a ready-to-use formulation that can be
used in basal bark applications as well.
Summary
Chinese privet infestations are extremely impactful to
the ecological and recreational values of a property. When deciding
as to whether or not to control a Chinese privet infestation, consider
seeking advice from an invasive plant control specialist who has
experience with privet treatments. Also, seek advice and assistance
from the local NRCS or state forestry or wildlife agencies to determine
if there is cost-share assistance available for controlling invasive
plants like Chinese privet. For example, in South Carolina, landowners
are receiving management planning and cost-share assistance for
Chinese privet control through several different agencies, including
NRCS conservation programs and US Fish and Wildlife Service Partners
Program. Whether you treat the site yourself, or contract the treatment
with a professional, it will take additional re-treatment and monitoring
to insure that the site remains free of privet. When a landowner
or land manager has a desire for improving the recreational, aesthetic,
wildlife, and ecological values of forests or open natural areas,
privet control treatments can be extremely rewarding.
About the author: CWC Chemical
employs Matt Nespeca as an invasive species consultant. Matt has
12 years of experience in vegetation management, and has worked
extensively with complex invasive plant problems throughout the
southeast. He worked for 7 years for BASF Corporation as a technical
specialist, sales representative and product manager. Matt has a
M.S. in Forest Biology from Virginia Tech, and a B.S. in Forest
Resource Management from Auburn University. Matt is both a registered
forester and commercial applicator, and partners with a network
of specialized applicators and professionals to provide results
for landowners, land managers and other clients.
1 Harrington and Miller, 2005: Effects of Application Rate, Timing
and Formulation of Glyphosate and Triclopyr on Control of Chinese
Privet (Ligustrum sinense), Weed Technology Vol. 19: 47-54.
Harrington and Ahuja, 2001: A Comparison of Timing, Rate and Formulation
of Glyphosate and Triclopyr for Control of Chinese Privet (Ligustrum
sinense), Proceeding of the Southern Weed Science Society, Vol.
54: 124
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