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A native to
tropical Asia, Dioscorea bulbifera or air potato was first
introduced to the Americas from Africa. It was introduced to
Florida in 1905. Due to its ability to displace native species
and disrupt natural processes such as fire and water flow, air
potato has been listed as one of Florida’s most invasive plant
species since 1993, and was placed on the Florida Noxious Weed
List by the Florida Department of Agriculture and Consumer
Services in 1999.
Air potato is in Yam Family. It is an herbaceous twining vine,
growing 70 feet or more in length. Leaves are broadly heart
shaped and alternately arranged on stems. A distinguishing
characteristic of air potato is that all leaf veins arise from
the leaf base, unlike other herbaceous vines such as morning
glories. Although considered to be a species of yam, these
plants are very toxic and should not be consumed.
Vegetative
reproduction is the primary mechanism of spread. This is through
the formation of aerial tubers, or bulbils, which are formed in
leaf axils. These vary in roundish shapes and sizes. In
addition, large tubers are formed underground, some reaching
over 6 inches in diameter.
Air potato can grow extremely quickly, roughly 8 inches per day.
It typically climbs to the tops of trees and has a tendency to
take over native plants. New plants develop from bulbils that
form on the plant, and these bulbils serve as a means of
dispersal. The aerial stems of air potato die back in winter,
but resprouting occurs from bulbils and underground tubers. The
primary means of spread and reproduction are via bulbils. The
smallest bulbils make control of air potato difficult due to
their ability to sprout at a very small stage.
Prevention is a
key step in the management of air potato. Bulbils are the
primary mechanism of spread, and research has shown even
minutely small propagules can sprout and form new plants. How
these bulbils are spread is speculative, but it appears movement
of contaminated brush, debris or soil is the primary mechanism.
Mowers and other brush-cutting equipment may also disperse long
distances, either through contaminated equipment or throwing of
the bulbils during the mowing operation. Spread via birds and
other animals may occur, but this has not been confirmed. Water
is also a major means of dispersal, so care must be taken to
first eliminate populations along water bodies where bulbils may
be easily spread. In addition, extra time must be utilized after
flood events, as spread may be extensive.
Cultural:
Weeds such as air potato generally invade open or disturbed
areas – following a burn, clearing mowing, etc., so these areas
are particularly vulnerable to invasion. Therefore, a healthy
ecosystem with good species diversity will help to deter
infestation.
Mechanical:
Mechanical methods are limited for air potato, as control of the
vines generally results in damage to the vegetation being
climbed/smothered by the air potato. Burning also results in
excessive damage to the native vegetation, as the fire follows
the vines into the tree canopy. Mowing will help to suppress air
potato, but as mentioned previously, this may increase the
overall problem sue to spreading of the bulbils.
Biological:
There is limited research and data on biological control of air
potato.
Chemical:
Chemical control is one of the most effective means of control
for air potato, but single applications will generally not
provide complete control. Contact Sarasota County Cooperative
Extension for recommendations. This is due to resprouting of
bulbils or underground tubers. Care must be exercised to
minimize off-target damage. If air potato vines are growing up
into trees or other desirable species, vines should be cut or
pulled down to minimize damage to the desirable vegetation.
Pulling the vines down without severing them from the
underground tuber will allow the herbicide to move into the
tuber and provide better control. The best time to apply an
herbicide is in the spring and summer when air potato is
actively growing. Be sure to allow adequate time for the plant
to regrow from the winter to ensure movement of the herbicide
back into the underground tuber. (As plants grow and mature,
they begin to move sugars back into the roots and below-ground
tubers). However, treat before the plants begin to form new
bulbils. Persistence and integration of control methods will be
the key to complete air potato management.
For more
information log onto
http://plants.ifas.ufl.edu/node/133 sensitive areas.
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