Yellow Sweetclover
 Family Fabaceae
Melilotus officinalis
Designation/Status
Arizona Noxious Weed List -
Not Listed
Federal Noxious Weed List – Not Listed
Origins
Eurasia
Plant Characteristics
Life Cycle:
Biennial, cool season legume. Flowers June and July and dies in
the second year. Bees are the main pollinators, as the plants do
not self fertilize. Produces up to 1,000,000 seeds per plant. Seeds
can last 40 or more years before germinating.
Visual
Appearance: Mature plants are 1-3ft tall. Leaves are
trifoliate, small yellow flowered clusters are borne at the ends
of stalks.
 Habitat
Open, disturbed areas, prairies, fields, agricultural land,
naturalizing in road cuts and borrow pits. Prefers regions where
precipitation is over 14 inches. However it is drought, salt and
cold tolerant but does not like shading or prolonged flooding.
Control Measures
Mechanical and Cultural:
Hand pulling before seeds have formed is quite effective (seeds
are resistant to both soil fumigation and solarization). Mowing is
not as effective as burning. Some fire tolerance when dormant, mow
the first year plants in August then burn is September for
control, Burn in March and early April to stimulate seedling
germination then burn in early May to kill second year plants,
burn in July of the next year to kill the plants that germinated
after the first burn, burning only one year tends to increase
populations. Plant can be grazed by cattle, deer and rabbits.
Biological: Native
sweet-clover weevil if present in high concentrations can help
with control though it has proven to be not reliable overall.
Chemical: 2,4-D is very
effective on first year plants, Glyphosate can be effective as
well.
Other Points of Interest
First recorded in 1664, used as a forage crop and honey
production.
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