Pigweed

Pers.], johnsongrass, pigweeds, and nutsedges were the most frequently reported weeds. 

Pigweeds Amaranthus spp. corn, cotton peanuts, sorghum soybeans, tobacco corn, sorghum soybeans, tobacco soybeans, corn CD... 

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. 

Treatment Grass 5 Redrootc,d Pigweed Q Common Lambsquarters c Common Ragweed... 

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. 

Teasdale JR, Mohler CL (1993) Light transmittance soil temperature, and soil moisture under residue of hairy vetch and rye. Agronomy J 85 673-680 Teasdale JR, Mohler CL (2000) The quantitative relationship between weed emergence and the physical properties of mulches. Weed Sci 48 385-392 Teasdale JR, Pillai P (2005) Contribution of ammonium to stimulation of smooth pigweed germination by extracts of hairy vetch residue. Weed Biol Manag 5 19-25 Teasdale JR, Beste CE, Potts WE (1991) Response of weeds to tillage and cover crop residue. Weed Sci 39 195-199... 

Pigweed Amaranthus spp., foxtail Setaria spp., velvetleaf Abutilon theophrasti Medikus Carpetweed Mollugo verticillata L., common... 

In studies on test meals, Walker et al. (32) discovered that the calcium of Swiss chard, which has a high oxalic acid content, was poorly absorbed. Children excreted more calcium during the 6 hours after a test meal of milk, Pumpkin leaves, cassava leaves, or pigweed leaves than after Swiss chard. All supplements contained 200 mg calcium. 

Compounds 272 are useful as herbicides and inhibitors of nitrification of amino nitrogen in soil, and they are used for the control of Echinochioa crusgalli without damage to rice. 5-Fluoromethyl-7-methoxy-l,2,4-triazolo-[l,5-a]pyrimidine-2-sulfonamides are useful for the control of pigweed (85USP4818273). 

Carotenoid Yellow to violet Dehydrated isoprene Carotene Pigweed (Amaranthus sp., Amaranth aceae) Sorrel (Rumex sp.) Little hogweed (Portulaca oleracea L.) ... 

The development of herbicide-resistant weeds has also been an influence on the selection of herbicides used on field corn or soybean. Weed resistance now affects nearly every decision a farmer makes about herbicide selection either a farmer is trying to control resistant weeds or is selecting herbicides that may reduce the possibility of weed populations becoming resistant. The adoption of the imidazolinone- and sulfonylurea-tolerant com hybrids mentioned above was in part a response to the presence of atrazine-tolerant pigweeds or kochia in many fields. However, a recent decrease in die use of imidazolinone and sulfonylurea herbicides can also be attributed to the development of populations of weeds that have become resistant to these herbicides. 

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)). 

Velvetleaf Tumble pigweed Sandhills amaranth Prostrate pigweed Bouchons amaranth Redshank, red amaranth or Italian amaranth Smooth pigweed... 

Yerkes et al. (1996) reported that although chlorophyll fluorescence measurements and C02 assimilation in resistant jimsonweed leaves were affected within 1 day of atrazine application, they returned to normal (at rates and levels equivalent to those in untreated leaves) within 5 days. Atrazine-resistant jimsonweed was cross-resistant to simazine, but was susceptible to prometryn, metribuzin, terbacil, and other herbicides. Chlorophyll fluorescence was unaffected in triazine-resistant pigweed, which showed cross-resistance to some triazines, moderate resistance to metribuzin and terbacil, and negative cross-resistance to bentazon and pyridate. 

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