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Weedy annuals include
3 life-cycle types here in Arizona.
Annuals
germinate in fall and die in early spring.
Summer
annuals germinate in early spring and die in fall with the first frosts.
Biennials
live for 2 years, but may produce seeds during both growing seasons.
Each
weed species requires a different eradication strategy, weather and time
of year also factors into weed control. By knowing the life cycles
of common weeds,control will be easier in the future.
To
General's weed control program
London Rocket
Russian thistle
Redstem Flaree
Sow Thistle
Annual Bluegrass
Links:
Pest
Management & Identification - Weeds listed by common name
London Rocket
Sisymbrium irio L.
London
rocket is a European native weed belonging to the mustard family,and
is one of the first winter weeds to appear in southern Arizona. It is abundant
in irrigated land in crops such as alfalfa and small grains, in gardens,
citrus orchards, pastures, and along roadsides. London rocket is a bright
green fleshy winter annual. The stems branch from the base 1 to 3 feet
high. It has a coarse taproot. Small, yellow flowers are borne on slender
stalks in small clusters at the stem tip.
Russian Thistle
Salsola
tragus
Russian
thistle was introduced from Russia and is an annual which reproduces
by seed. It is a round, bushy, much-branched plant growing 1 to 3-1/2
feet high. The branches are slender, succulent when young, and woody when
mature. Russian thistle grows on dry plains, in cultivated fields,
roadsides, and waste places, chiefly in grain-growing areas.
At maturity, the plant breaks
off at the base and because of its round shape becomes an excellent
tumbleweed.
Links:
ARID_GARDENER:
Pest of the month
Redstem Flaree
Erodium
cicutarium
Redstem
Flaree was introduced from Europe native to Mediterranean region. Annual
or winter annual, reproduces by seeds. Overwinters as rosette and blossoms
in early spring. Flowers April to June and is one of earliest flowering
plants in spring.Widespread across North America, abundant on Pacific Coast.
A weed in fields and waste
places, sometimes lawns, pastures, and on dry soil
Sow Thistle
Sonchus
oleraceus
Sow
Thistle, a native to Europe, is a tall, course annual with milky juice.
Sow Thistle is found in cultivated fields, meadows, roadsides and waste
places. A perennial reproducing by seed and underground roots. The stems
are hollow, smooth and branching at the top. The flower is yellow, dandelion-like.
Annual Bluegrass
Poa
annua L.
Annual
Bluegrass, a turfgrass weed that grows best in cool, moist conditions
and rich soil but tolerates a variety of conditions including compacted
soils. This weed lives as an annual and perennial. Reproduction by seed
and favors golf greens and cool, moist conditions. Annual bluegrass can
be controlled with pre- and post-emergence herbicides.
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