Carelessweed, Pigweed

Amaranthus spp.

Amaranthaceae


Description

Carelessweeds are annual weedy herbs belonging to the amaranth family. Texas has 23 recorded species, which vary in growth forms from prostrate to branching upright. Carelessweed is often called pigweed because swine relish it. It bears inconspicuous flowers from June to November.


Habitat

Carelessweed abounds on disturbed sites - especially in barnyards with rich, moist soils throughout most of the United States. It is also a common weed in croplands.


Toxic Agent

Carelessweeds can accumulate nitrates from the soil to toxic levels. Environmental factors often influence nitrate accumulation. For example, nitrate poisoning is more likely to occur if the plant is growing in soils high in nitrogen, especially during drought.

Plants containing more than 1 percent nitrate are dangerous. The plant is also known to cause bloat. All ruminants are susceptible to nitrate poisoning.


Signs of Livestock Ingestion

Animals with acute nitrate poisoning are often found dead with no previous history of illness. Less acute nitrate poisoning signs often occur in this order: Weakness; Unsteady gait; Collapse; Shallow and rapid breathing; Rapid pulse; Dilated pupils; Delayed abortion; Coma; Death; Blood may appear chocolate brown at time of death.

Pregnant animals surviving acute nitrate poisoning may abort 3 to 5 days later.Animals with acute nitrate poisoning are often found dead with no previous history of illness. Less acute nitrate poisoning signs often occur in this order: Weakness; Unsteady gait; Collapse; Shallow and rapid breathing; Rapid pulse; Dilated pupils; Delayed abortion; Coma; Death; Blood may appear chocolate brown at time of death.

Pregnant animals surviving acute nitrate poisoning may abort 3 to 5 days later.


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