Redroot pigweed

Amaranth (pigweed, redroot, wild beet), Amaranthus spp... 

In another greenhouse study, sunflower debris increased the P0 concentration of redroot pigweed but did not alter the concentrations of B or K (21). When nutrient solutions were added, the P0 and N responses were the same, but K+ was slightly Increased by the debris. 

Amaranthus Palmeri S. Wats., Palmer amaranth, is a coarse, weedy, drought-resistant, dioecious member of the Amaranthaceae and is related to A. retroflexus L., redroot pigweed, and the ornamentals k. tricolor L., sumner poinsettia, and /. caudatus L., love-lies-bleeding. Palmer amaranth was used by natives of the North American desert as a protein source and cereal to supplement maize and beans. Another member of the same family, A. spinosus L., spiny amaranth, has been reported to exhibit allelopathic activity toward coffee... 

Common millet Panicum miliaceum L., barnyard grass E. crus-galli (L.) P. Beauv., bristly foxtail Setaria verticillata (L.) P. Beauv., redroot pigweed Amaranthus retroflexus L. 

Weed species resistant to the triazines that have been found in one or more fields in 10 or more states, provinces, or countries include smooth pigweed, Powell amaranth, redroot pigweed, common lamb s-quarters, kochia, common groundsel, black nightshade, and annual bluegrass (Tables 10.1(a) and 10.1(b)). 

In studies with a sulfonyl-resistant biotype of redroot pigweed, the first weed in Israel to exhibit ALS resistance, Sibony et al. (2001) found it was cross-resistant to all other classes of ALS herbicides. From nucleotide sequencing, they concluded that a proline to leucine change in Domain A at position 248 is the only difference in the amino acid primary structure of the regions sequenced, indicating that it is responsible for all ALS inhibitor resistance observed. 

Ferguson et al. (2001) confirmed resistance to ALS inhibitors (imazethapyr or flumetsulam) in populations of Powell amaranth and redroot pigweed in Ontario. High-level cross-resistance to thifensulfuron was found in two populations of each species. On the other hand, Poston et al. (2001) found that a population of imidazolinone-resistant smooth pigweed was 10-fold more sensitive to cloransulam-methyl (another class of ALS inhibitors) than the sensitive population. 

McNaughton, K.E., J. Letarte, E.A. Lee, and E.J. Tardif (2005). Mutations in ALS confer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii). Weed Sci., 53 17-22. 

Research by an Iowa State University botanist concluded that on the nonchemical farm, weed populations in the plots hoed four times were similar to those in herbicide-treated fields on other farms (Jurik, 1993). He also estimated that seed production from redroot pigweed that emerged on the farm was between 40 million and 400 million total seeds per acre (100 million to 1000 million seeds per ha). In an effort to improve the efficacy of the rotary hoe operations, experiments have been conducted using double rotary hoe passes on fields on the same day (Thompson and Thompson, 1994). 

Redroot pigweed Amaranthus retroflexus (L.) Gliocladiiim virens Miller, Giddens Foster peat moss contg. 22 sucrose and ammonium nitrate ... 

Strek HJ, Weber JB. 1982b. Adsorption and reduction in bioactivity of polychlorinated biphenyl (Aroclor 1254) to redroot pigweed by soil organic matter and montmorillonite clay. Soil Sci Am J 46(2) 318-322. 

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