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Seedling
Stem
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Tumbleweed, Russian
Thistle
(Salsoa kali var. tenuifolia)
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Description
Tumbleweed is a many branched, annual herb growing to a height
of 2 to 6 feet. The plant forms a stiff, prickly, round, bushy
plant at maturity. The spine tipped leaves are oval shaped.
The stems have distinctive dark purplish striations (parallel
to the stem) when the plant is young and growing. It is a
member of the goosefoot family (Chenopodiaceae).
Distribution and Habitat
Tumbleweed is found in every region of the Texas
with the exception of the Pineywoods and the Post Oak Savannah.
This plant is most abundant along roads, irrigated fields
and in disturbed areas.
Regions: 2, 4,
5, 6,
7, 8,
9, 10.
Toxic Agent
Nitrate is the toxic agent. All ruminants are susceptible
to nitrate poisoning, with cattle more frequently poisoned
than other animals. Plants containing more than 1.5 percent
nitrate are dangerous, and nitrate consumption in amounts
as little as 0.05 percent of the animals weight may be lethal.
Environmental factors often influence nitrate accumulation
by such plants. For example, nitrate poisoning is more likely
to occur if the plant is growing in soils high in nitrogen,
such as livestock pens or areas fertilized. Excessive shade,
lack of water, and stress or physical damage may also increase
nitrate levels.
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Livestock
Symptoms
With acute nitrate poisoning, animals are often found
dead with no previous history of illness. Less acute nitrate
poisoning can be identified by the following symptoms, in the
order of their appearance:
- weakness
- unsteady gait
- collapse
- shallow and rapid breathing
- rapid pulse
- dilated pupils
- abortion
- coma
- sudden death
Un-pigmented parts
of the body, such as the whites of the eye, the tongue
and lips will often have a blue-brown discoloration, while
the blood may be chocolate-brown in color.
Integrated Management Strategies
Areas infested with this
plant should be avoided if they have received a heavy
application of nitrogen fertilizer, during drought or
after a period of extended cool and cloudy weather. Rations
high in carbohydrates will also help reduce losses from
nitrate poisoning. Animals poisoned should be kept quiet
and administered methylene blue intravenously. Generally,
a 1 to 4 percent solution which also contains 5 percent
dextrose at a rate of 1 gram of methylene blue per 250
pounds of animal weight should be used. Diagnosis of nitrate
poisoning should be certain before treatment with methyl
blue.
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