Tifft Nature Preserve Management Plan - Buffalo Museum of Science

Biological Control – There are currently no USDA approved biological control
agents for Japanese knotweed and research on this topic is being considered but
has not begun (Shaw and Seiger 2002).
Garlic Mustard (Alliaria petiolata)
Garlic mustard is a biennial European plant that is rapidly invading forests and
woodlands in eastern North America. Garlic mustard colonizes disturbed areas, but
unlike most other invasive species, it has the ability to invade intact forest communities
(Blossey et al 2005). The plant can form large near-monotypic stands that blanket the
forest floor and lead to the decline of native understory vegetation. Recent research
has suggested that garlic mustard suppresses the growth of native tree seedlings
through antifungal phytochemistry (Stinson et al 2006) and limits tree regeneration by
suppressing arbuscular mycorrhizal fungi (Matin and Titus 2008). Like all mustards,
garlic mustard produces many tiny seeds that are dispersed on the fur of animals,
flowing water, movement of dirt for fill or landscaping, and even on hiker’s boots. These
seeds can remain viable in the soil for up to ten years.
At Tifft Nature Preserve, garlic mustard is abundant in the woodlands and has
been present since the early 1980’s when Klips et al (1993) described it as widespread
with a few dense colonies occurring. There have been no major efforts to control the
plant and after flowering and setting seed for three decades the seed bank will be large
and take up to ten years to exhaust. Despite the challenge of controlling garlic mustard,
efforts should made due to the negative effects the plant has on tree seedlings and the
importance of improving tree regeneration on the preserve. Since the plant is a biennial
and only sets seed in its second year, control efforts should target these seed producing
plants. Several control options are discussed below.
Hand Pulling – Hand pulling the plant is convenient since it requires no
equipment and volunteers can be trained in minutes. Second year plants can be
pulled early in the spring and into the summer, as long as they are pulled before
the seed pods open. Efforts to pull the entire S-shaped root should be made
since a broken off root will continue to grow. Pulled plants need to be bagged
and discarded in the trash (do not compost) since the seeds will continue to
develop. Although hand pulling works well for small infestations or around
sensitive vegetation where herbicides would be inappropriate, hand pulling alone
will not control garlic mustard on the preserve.
Herbicide Application – Herbicides are commonly used to control garlic mustard
since the extent of invasion often leaves no other option. Foliar applications of
glyphosate (e.g. Roundup) or 2,4-D will kill the plant, but care needs to be taken
since these are nonselective herbicides and other vegetation will be affected.
However, garlic mustard greens up early in the spring when most native
vegetation is still dormant and application at this time of year will reduce damage
to non-target plants. All individuals mixing, applying or handling herbicides need
to be Certified Pesticide Applicators by the NYS DEC.
Tifft Nature Preserve Management Plan 25