spp.][CDFA list: C] Photographs
Giant dodder [Cuscuta
reflexa][Bayer code: none][CDFA list: A][Federal Noxious Weed] Photographs
Map of Distribution
hair, witchs hair, tangle gut, strangle gut, devils
gut, love vine, witchs shoelaces.
DESCRIPTION:Annual stem parasites with
leafless, thread-like, orange, red, or yellow stems
that twine over other plants. Dodder can be problematic in agricultural
crops, especially alfalfa and tomatoes. In addition, dodder seed
is difficult to exclude from commercial alfalfa, clover, or flax
Develop a small temporary root to support a thread-like shoot,
4-10 cm long. Shoot moves slowly in a circular pattern as it grows
until it touches a support. Upon contact with a suitable host,
knob-shaped organs (haustoria) develop to penetrate the host stem.
Seedlings die without a host within 10 days to several weeks depending
on the species.
1-2 mm thick, glabrous, lack leaves or have appressed, scale-like
leaves about 2 mm long; red, yellow, or orange, but contain some
chlorophyll and are sometimes tinged green. Growing stems branch
and attach to new host stems with haustoria. Each dodder branch
obtains nutrients from the host independent of older branches.
One plant can cover 10-15 ft2.
and UNDERGROUND STRUCTURES:Modified into specialized knob-shaped organs (haustoria)
that penetrate host stems.
depending on species, but generally May-October. Bell-shaped.
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and SEEDS:Capsules spherical, ovoid, or conical; open irregularly
or like a lid at the top (circumscissile). Seeds 1-4, spherical,
oblong, ovoid, or angular.
CHARACTERISTICS:Frost kills plants, but haustorial tissue of some
species can overwinter in host stems and develop new stems the
following spring. Stems do not persist through winter.
communities, but sometimes infests nursery crops, landscaped sites,
and agricultural crops, especially alfalfa, clovers, and tomatoes.
Host range is broad, but monocots (excluding asparagus) are seldom
by seed and vegetatively. Broken
stems can develop new haustoria. Seed disperses by water, animal
ingestion and movement, and especially human activities and machinery.
A proportion of seed has a hard coat that must be weakened by
scarification, microbial decomposition, and winter chilling before
germination can occur. Germination does not require the presence
of a host plant. Under favorable conditions, seed can germinate
in the fruits. Seed can remain viable for at least 10 years in
the soil. Emergence is typically from the top 5 cm of soil. In
most years, the period of emergence ends by mid-May in the Central
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FAVORING/DISCOURAGING SURVIVAL:Many options are available to help decrease crop
infestations. Useful methods include hand cultivation, spot or
field burning, close mowing, later planting time (mid-May or later),
and crop rotation to cereals or corn. Prevent the spread of dodder
seed by thoroughly cleaning agricultural machinery immediately
after it has been used in an infested field. Hand cultivation
is most efficient at 30 days after planting a crop and repeated
at 50 days.
twining, orange, red, or yellow stems easily distinguish this genus.
A thorough report of dodder control in seed alfalfa has
been produced by Shannon Mueller through University of California Cooperative
Extension, Fresno County. The report can be accessed on the World Wide Web at
the following address: http://alfalfa.ucdavis.edu
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