Agriculture Reference
In-Depth Information
Redroot Pigweed (a.k.a., green pigweed,
Chinaman's greens, careless weed, green
amaranth, redroot, rough pigweed)
Redroot pigweed is a member of the Amaranth genus, specifically Amaranthus retroflex-
us . It is an annual that reproduces from seeds and can prove quite troublesome in cultivated
crops, orchards, vineyards, etc. As with Amaranthus hybridus, Amaranthus retroflexus can
cause nitrate poisoning of livestock when mature. Amaranthus retroflexus stands four to six
feet high, and branches freely. The taproot of redroot pigweed is quite red. Flowers are
small and green and grouped in spikes. Seeds are black, glossy and lens-shaped or oval.
Leaf tips are notched with the midvein reaching the notch with a temporary bristle. Amar-
anthus retroflexus is easy to control. Joe Cocannouer, in Weeds, Guardians of the Soil , did
not see redroot pigweed as a big nemesis, even though it signals a calcium-potassium ratio
out of whack, potassium too high, calcium too low, with a resultant shortfall in humus. The
phosphate complex also needs attention when the weed proliferates. Calcium, phosphorus,
copper, molybdenum, carbohydrates, humates and vitamin C in some areas will reduce or
chase away this weed when it dominates a field. Chemicals and salts in undigested ma-
nures, magnesium and potassium chloride often contribute to redroot proliferation.
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