eFloras 2011 [Online]. (Available online at, Brainard, D. C., A. DiTommaso, and C. L. Mohler. photo by Robert Videki via Doronicum Kft., Bugwood.org, Click above for the chemical control of Redroot Pigweed from the Cornell Weed ID site. Tumble pigweed has a shrubby growth habit, and prostrate pigweed extends its stems parallel to the ground (this is often a sidewalk-crack rather than an agricultural weed). (Available online at: Knezevic, S. Z., S. F. Weise, and C. J. Swanton. 2b), and Powell amaranth (Fig. Powell amaranth (A. powelii) 4. Veins of the leaf lower surface are predominantly white. (Available online at, Brainard, D. C., R. R. Bellinder, and A. DiTommaso. The three species are discussed together because they are difficult to distinguish from one another in the field, have similar life cycles and habits of growth, and present similar management challenges in crop production. 2c) … redroot pigweed or Powell amaranth. However, the competitive effects of smooth pigweed on lettuce has been attributed by the weed's rapid uptake of soil P (Santos et al., 1998). Male and female flowers are separate and the male flowers fall off soon after the pollen sheds. These are still susceptible to flaming or cultivation, but will become much tougher to control if allowed to grow beyond this stage. • Male and female flowers on same plant. Figure credit: Lynn Sosnoskie, University of Georgia, Bugwood.org. Leaves are round to oval in shape and have prominent veins; both leaves and stems are covered in fine hairs (pubescent). If you have a garden and the weeds get out of hand, no problem! Pigweed identification can be difficult, especially at the seedling stage of growth. Studies in Florida indicate that heavy canopy-forming summer cover crops such as cowpea, velvetbean, and sunn hemp can suppress the growth of smooth pigweed, provided that cover crops are planted in narrow rows and sufficiently high seeding rates to promote early canopy closure (Collins et al., 2008). Blades are dull and green above while hairy beneath or at least along the veins. A. Photo credits: (a) Joseph M. DiTomaso, University of California - Davis, Bugwood.org. Homepage; Broadleaf; Grasslike; Other; redroot amaranth. 1994. Base of plant. Redroot Pigweed. The leaves are alternate, stalked, dull green, oval-shaped, rough and 3-4 inches long. 1 and 2a), smooth pigweed (Fig. Close mowing or weed-whacking between crop rows can greatly reduce seed formation, though axillary buds at basal leaf nodes on the stem can regenerate side shoots and thereby set seed. Cooperative Extension Service, Kansas State University. This can be similar to redroot or smooth although they tend to be more egg shaped and widest in the middle. This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Response of weeds to soil phosphorus and potassium. Temperature effects on germination of nine. Uva R H, Neal J C, DiTomaso J M. 1997. Bryson, C. T., and M. S. DeFelice. Branches are usually longer than those of redroot pigweed. 1998. 5), and may overtop lower growing vegetables, causing a crop loss. 44. The redroot pigweed grows to 2-6 inches in height. A. Dusky, W. M. Stall, and D. G. Shilling. In Powell amaranth, inflorescences are linear or sparingly branched, with branches 4–8 inches long and thicker than a pencil (Horak et al., 1994) (Fig. They are ovate or rhombic-ovate. (Available online at: Tompkins, D. K., D. Chaw, and A. T. Abiola. 2007. Redroot pigweed grows in cultivated fields, pastures, roadside ditches, and undeveloped areas. Pigweed causing farmers to rethink farming methods. One effective management method is a stale seedbed, including a one- to two-week lag between initial and final seedbed preparation in late spring or summer. The stems are erect, light green, stout, branched, 60 … Weed Science 44:74–86. It is a common annual weed, producing many seeds that remain viable for up to 5 years. During weed-crop competition, pigweeds respond to partial shading by increasing stem growth and deploying foliage at greater heights above the ground, thereby enhancing light interception. • Flowering structure is branched, with many thick, flowering stems that range from 4 to 7 inches in length (Figures 1 and 2). If those weeds are Redroot Pigweed Amaranth. Pigweed identification can be difficult, especially in the early stages of seedling growth as many species look the same. Amaranth Identification The first and often critical key to managing Palmer amaranth, or any weed for that matter, is to scout and identify the species that exist in each agronomic field. Erect summer annual. A buckwheat green manure suppressed the emergence and growth of Powell amaranth, partly by taking up available soil N, and partly by releasing allelopathic compounds from decaying buckwheat residues (Kumar et al., 2008, 2009). Presence of hairs on the leaves, stem, and petioles indicates that it is redroot or smooth pigweed. Interference of redroot pigweed (. All three pigweed species emerge mostly from seeds in the top 0.5 inch of the soil profile, and rarely from below 1 inch. Leaves are diamond-shaped to oval or egg-shaped with the broader end nearest the petiole (ovate). At emergence before a full set of true leaves appear, pigweeds can be confused with other weed species such as wild buckwheat, eastern black nightshade, and ladysthumb. Teyker, R. H., H. D. Hoelzer, and R. A. Liebl. Photo credit: (a) Phil Westra, Colorado State University, Bugwood.org; (b) Phil Westra, Colorado State University, Bugwood.org. Redroot pigweed emerging with crops demonstrated this response in field trials in Ontario; however, higher levels of shade (due to higher crop population, or later weed emergence relative to the crop), greatly reduced the weed's growth and development (McLachlan et al., 1993a, 1993b). and WNMU). Comparative growth of six, Steckel, L. E., C. L. Sprague, E. W. Stoller, and L. M. Wax. Redroot pigweed (Amaranthus retroflexus) can be found in a wide range of soil textures and types though it is usually found in open areas that are exposed to the elements. 1998. Weeds of the South. (a) Two-leaf stage of redroot pigweed, easily killed by shallow cultivation or flame weeding. Its most common habitats are roadsides, waste places, gardens, and river banks. Seedhead and leaves of redroot pigweed. Mature plant: Stems of the mature plant are stout with a thick and smooth lower part and a hairy, branched upper part. Smaller inflorescences may also occur in upper leaf axils. Redroot Pigweed; Virginia Pepperweed; Witchgrass; Yellow Nutsedge; Vegetables Toggle the sub-menu. Various mammals, including mice, also eat Pigweed seeds. Although seed longevity in soil up to 20 years has been reported, the majority of seeds either germinate or become nonviable within several years after they are shed. Green and smooth pigweed very similar. Nitrogen fertilizer rate effects on weed competitiveness is species dependent. Redroot pigweed. 130. Pigweeds have the C4 photosynthetic pathway, which gives them an ability to grow and develop rapidly in high temperature and high light conditions. Redroot pigweed. 2000. Timely cultivations or flame weeding during late spring and early summer, followed by organic mulch, have been found effective for managing Powell amaranth in upstate New York (Mohler and DiTommaso, unpublished), and are likely equally effective for smooth and redroot pigweeds. Image Gallery ; Similar Species. This guide will help in making a correct identification based on typical pigweed characteristics. Seed maturation generally occurs a few weeks earlier in Powell amaranth and northern populations of redroot pigweed than in smooth pigweed; thus, the former two species are better able to complete their life cycle within a short frost-free season. The stout, hairy stem can grow up to 6 1/2 feet in height. • Powell amaranth is very similar to redroot pigweed and smooth pigweed. Deeper burial in the soil profile enhances seed dormancy and longevity in redroot pigweed (Omami et al., 1999). Because of the great genetic variability, adaptability, and hybridization potential of these three weeds, populations at different locales may respond differently to temperature, other germination stimuli, and weed control tactics. For example, seeds from Powell amaranth growing on dairy farms in upstate New York with a corn – alfalfa (multi-year) rotation were more dormant and longer lived than Powell amaranth seeds from fields under intensive vegetable production (Brainard et al., 2007). Publication anticipated in 2012. Fall moldboard plowing in plots with high seed populations reduced redroot pigweed emergence the following spring by more than 90 percent (from 3,500 to 250 per 10 square feet), but plowing fields in which seed production had been prevented for six years brought deeply buried seeds to the surface, and thereby increased emergence from 1 to 25 per 10 square feet. 2011. Slender pigweed, also known as Green pigweed Seed germination in redroot and smooth pigweeds is promoted by high temperatures (86–104°F), diurnally fluctuating temperatures (e.g., 59°F / 95°F), and light (Guo and Al-Khatib, 2003; Schonbeck and Egley, 1980; Steckel et al., 2004)–stimuli which are related to proximity to the soil surface and absence of shading vegetation. Uncomposted manure is a common source of pigweed seeds. Redroot pigweed (, Schonbeck, M. W., and G. H. Egley. Guo, P., and K. Al-Khatib. The stem of the pigweed is what makes this plant so distinctive. Seeds are produced late summer through fall. redroot pigweed (Amaranthus retroflexus) Identification Tips tall, erect, branching summer annuals that reach heights of 3–6 feet and occasionally more Stems and leaves may be smooth and hairless, or covered with fine hairs. A Quick Pigweed Identification Exercise Aaron Hager. Permalink . Flowering structure is highly branched with male and female flowers on the same plant. University of Arkansas Cooperative Extension Service. Stems & Roots: Stems erect, 10cm-2m (4in.-6½ft) high, but usually 50-90cm (20-36in. If you have a disability and are having trouble accessing information on this website or need materials in an alternate format, contact web-accessibility@cornell.edu for assistance. Its most common habitats are roadsides, waste places, gardens, and river banks. Figure 3. Smooth and redroot pigweed have an upright habit like Palmer amaranth and waterhemp, but both have at least slightly hairy stems. Plants have a long, fleshy, reddish to pink taproot and stems that are erect, light green, branched, 23-35 inches high, rough and angular. The leaf margins are wavy and the petioles are purplish and hairy. Phosphorus effects on the competitive interactions of smooth pigweed (, Schonbeck, M. W., and G. H. Egley. There are from 65 to 75 species of amaranths, many of which are important field weeds. Omami, E. N., Haigh, R. Medd, and Nicol. Weeds of the Northeast. Life cycle: Summer annual Growth Habit: Erect Propagation: Seed Leaf Margin: Wavy Leaf Hairs: Hairy petioles Leaf Structure: Ovate or rhombic-ovate Leaf Arrangement: Alternate Root Type: Taproot Flower Color: Greenish. In growth chamber experiments conducted under two day/night temperature regimes (72°F / 57°F, and 82°F / 72°F), and in field trials in Ontario, Canada, Powell amaranth germinated and grew more rapidly–and produced more seed–than either redroot pigweed or smooth pigweed (Weaver, 1984). Changes in germinability, dormancy, and viability of, Qasem, J. R. 1995. Plants have a long, fleshy, reddish to pink taproot and stems that are erect, light green, branched, 23-35 inches high, rough and angular. 4d). It has a long, fleshy, reddish to pink taproot. I thought it might be a good idea to refresh weed identification skills based on characteristics of the flowering structure. In the axils of the lower leaves are small clusters of flowers arranged on a branched stem (inflorescences). Redroot pigweed, a summer annual broadleaf plant, is found up to 7900 feet (2400 m) in the Central Valley, northwestern region, central-western region, southwestern region, Modoc Plateau, and most likely in other California areas. Photo credit: Phil Westra, Colorado State University, Bugwood.org. The inflorescence has a stiff, rough texture (hence the other common name for this species, "rough pigweed"), and consists of a much-branched spike with individual branches usually less than 2 inches long, and thicker than a pencil (Horak et al., 1994) (Fig. Weed Identification. The leaves are hairy … Effect of windrow composting on weed seed germination and viability. The allelopathic effect of three, Santos, B. M., J. Assessing variability in fecundity of Amaranthus powellii using a simulation model. Seedlings Stems below the cotyledons (hypocotyls) are without hairs (glabrous) but may sometimes be slightly hairy, and are often red in color, especially near the base. If you have a garden and the weeds get out of hand, no problem! Top view of the mature leaves of a redroot pigweed, photo by Howard F. Schwartz from Colorado State University via Bigwood.org. Seedlings Stems below the cotyledons (hypocotyls) are without hairs (glabrous) but may sometimes be slightly hairy, and are often red in color, especially near the base. 2008. In New York, a summer cover crop of cowpeas with sorghum-sudangrass or Japanese millet suppressed Powell amaranth growth and seed production, whereas the weed outcompeted cowpea alone in a hot, dry year (Brainard et al., 2011). 1 and 2a), smooth pigweed (Fig. Plant and Soil 135: 287–292. This guide will help in making a correct identification based on typical pigweed characteristics. Mohler, C. A., and A. DiTommaso. Seedlings can be eliminated by harrowing spring grains between the 3-leaf stage and stem elongation. Plants are erect and usually around 3-4' in height, although they can grow larger. Plants have numerous flowers that are small, green and crowded into dense, finger-like spikes. Fruit (1.5-2 mm (~1/25”) long) are thin-walled and each contain a single shiny black/brown seed. Avoid broadcast applications of chicken litter or other concentrated nutrient sources, as these will stimulate rapid early growth of pigweeds, which may take up most of the nutrients before the crop can access them. Green and smooth pigweed very similar. Freshly formed seeds require higher temperatures than seeds that have overwintered in the soil (Mohler and DiTommaso, unpublished; Schonbeck and Egley, 1981). Amaranth, Spiny Amaranthus spinosus; Lambsquarter Chenopodium album Redroot pigweed (Amaranthus retroflexus) Redroot pigweed is characterized by it's red tap root (usually present at the seedling stage of development), from which the plant gets it's name. Amaranth, Spiny Amaranthus spinosus; Lambsquarter Chenopodium album Photo credits: (a) Robert Vidéki, Doronicum Kft., Bugwood.org, (b) Mark Schonbeck, Virginia Association for Biological Farming, (c) Lynn Sosnoskie, University of Georgia, Bugwood.org. Redroot Pigweed Seedling: Redroot Pigweed Flowers: Redroot pigweed is a summer annual that reproduces only by seed. In Ontario, redroot pigweed that emerged in corn at the 3–5-leaf stage at populations of 0.5–2.5 weeds per foot of row reduced yields 10–30%, whereas pigweed emerging at the 7-leaf stage had little effect (Knezvic et al., 1994). Redroot pigweed – Amaranthus retroflexus. Palmer amaranth (Amaranthus palmeri) … Flowers are greenish and small. (c) Foliage of young Powell amaranth plants. "A Quick Pigweed Identification Exercise." Dr. Mark Schonbeck, Virginia Association for Biological Farming. Many cultivation implements can be adjusted to move sufficient soil into rows of established crops to bury within-row pigweed seedlings that are less than 1 inch tall. MATURE (photo 4) • Very small fine hairs are found throughout plant. Whereas another pigweed species, Palmer amaranth, showed much higher growth rates, redroot pigweed is more tolerant of cool temperature regimes (Guo and Al-Khatib, 2003). A., R. J. Smeda, W. G. Johnson, J. The leaf shapes of Palmer amaranth are ovate to diamond shape and widest at the base. In Mississippi, redroot pigweed seeds buried 4 inches deep (from which seedlings cannot emerge) in field conditions showed a 93% loss of viability within 8 months (Schonbeck and Egley, 1981). Redroot pigweed Amaranthus retroflexus L.. Family: Amaranthaceae Life cycle: Annual Native status: Native to North America Habitat: Crop fields, waste areas General description: Erect, branched plant reaching heights of 6 ft. Key ID traits: Stems hairy; leaves are egg-shaped and often reddish underneath and with wavy margins; first leaf usually has notch at tip. Key features of seedling and mature plants that aid in distinguishing the pigweed species are presented in this guide. Top of flowering plant. High-temperature effects on germination and survival of weed seeds in soil. If those weeds are Redroot Pigweed Amaranth. A. Kendig, and M. R. Ellersieck. Also known as Pigweed or Amaranth. Redroot pigweed seedling - notched tip, small fine hairs, ovate shaped leaves. Pigweeds that emerge with the crop and are not controlled can substantially reduce crop yields (Fig. Available at. Sprouted pigweed seeds can be added to salads while the tiny pigweed seeds can be roasted, crushed and used as cereal substitute. A Quick Pigweed Identification Exercise Aaron Hager. Powell amaranth grown with broccoli or broccoli + rye intercrop during a warm season responded to canopy shade with increased stem growth, whereas in a cooler season, the weed was more readily suppressed by crop competition (Brainard et al., 2005). The inflorescence of smooth pigweed is similar in size and degree of branching, but has a much softer texture (hence, "smooth pigweed"), and individual branches usually no thicker than a pencil (Horak et al., 1994) (Fig. Weed identification at the seedling and immature stages can be difficult but is often necessary because scouting should occur before weeds reach 4 inches in height. In addition, local populations are likely to adapt and become more competitive if the same weed management strategies are utilized year after year. The lower stem and taproot are reddish colored. Redroot and smooth pigweeds (Amaranthus retroflexus L. and A. hybridus L.) Powell amaranth (Amaranthus powellii) In redroot pigweed, the tepals are all longer than the fruit itself; in smooth pigweed, they are all shorter than the fruit and have dark green mid-veins; and in Powell amaranth, tepals are very unequal in length with some longer and some shorter than the fruit (Costea et al., 2004). Figure 2. The goal is to "keep the weed guessing" by varying the timing of cultivation, crop competition, and other stresses on the weed population. 1993b. Leaves. (Available online at: Kumar, V., D. C. Brainard, and R. R. Bellinder. Lack of hairs. What It Looks Like. Flowering pigweeds. A. Changes in sensitivity of, Schweizer, E. E., and R. L. Zimdahl. It's origin is murky, though it may be native to eastern North American and/or Central America. Habit. Suppression of Powell amaranth (Amaranthus powellii), shepherd's-purse (Capsella bursa-pastoris), and corn chamomile (Anthemis arvensis) by buckwheat residues: Role of nitrogen and fungal pathogens. (For reference, some seedlings may penetrate 3,600 lb/acre of loose straw.). Severing pigweed plants below the cotyledonary node (i.e., at or just below ground level) can prevent shoot regeneration (Costea et al., 2004). 4c). (Available online at. At emergence before a full set of true leaves appear, pigweeds can be confused with other weed species such as wild buckwheat, eastern black nightshade, and ladysthumb. To print a fact sheet, use the "Print" command in your browser. Male and female flowers are borne together on the same plant (monoecious). Leaves are diamond-shaped to oval or egg-shaped with the broader end nearest the petiole (ovate). Redroot Pigweed is a found in field crops, vegetables, abd small fruit. So if a pigweed plant has a red root, this does not always identify the plant as redroot pigweed! Although reducing tillage may not in itself lower pigweed populations or help in the management of these weeds, surface residues of winter cover crops rolled down for no-till planting of a subsequent production crop may be quite effective. Smooth Pigweed. IDENTIFICATION. 1999. Common Waterhemp, C. Green pigweed, D. Redroot pigweed. Once mature, identification is less difficult but not altogether straight forward. The biology of Canadian weeds. Manage weeds on your farm: A guide to ecological strategies. Redroot Pigweed is found in all manner of disturbed soils such as roadsides, railroads, cultivated fields, weedy shores, vacant lots, old homesteads and backyard gardens. Look for an upcoming book from Dr. Mohler on ecological management of weeds, from Cornell University Press. Weed Science 55: 218–226. Both the fresh or dry pigweed leaves can be used to making tea. photo by Phil Westra via Colorado State University, Bugwood.org. The northern field cricket and certain species of ground beetles feed on the seeds lying in the soil surface. To avoid adding weed seeds to crop fields, raw manure and any other organic materials that may contain viable pigweed seeds should be hot-composted for at least four weeks, with several turns to ensure thorough heating of all the material, before application. Unpublished. 3). Pigweeds profile webpage from the Michigan State University’s Department of Plant, Soil, and Microbial Sciences. Redroot pigweed Russian thistle Shepherdspurse Smartweed, Pennsylvania Spiny sowthistle Spurge, prostrate Spurge, leafy Sunflower, common Teasel, common and cutleaf Thistle, bull Thistle, Canada Thistle, musk Thistle, Russian Velvetleaf Venice mallow Waterhemp Wild buckwheat Wild carrot Wild parsnip Wild violet Woodsorrel, yellow Yellow woodsorrel. (Available online at: Flora of North America. Pigweeds are prolific seed producers that cancontinue to form seeds even after mowing or tilling, so it is important to clean up fields soon after harvest and Remove plants that have flowered from the field. Figure 5. Cotyledons are linear with a prominent midvein and reddish tinted undersides. Maize and pigweed response to nitrogen supply and form. Image courtesy of Larry Kuhns. Interference of redroot pigweed (Amaranthus retroflexus), Palmer amaranth (A. palmeri), and common waterhemp (A. rudis) in soybean - Volume 51 Issue 1 - … Redroot pigweed, smooth pigweed, and Powell amaranth are three closely-related amaranths that have become serious cropland weeds throughout the United States and into southern Canada. The redroot pigweed grows to 2-6 inches in height. As biological control agents, Pigweed seeds are consumed by various seed predators. Pigweeds have been described as weeds of rich soils (Weaver and McWilliams, 1980), as high levels of readily available nitrogen (N) and phosphorus (P) seem to stimulate weed growth and nutrient uptake, and to intensify competition against crops. Virtually every farmer in North America knows and grapples with pigweed, a term that covers several species in the genus Amaranthus, including: 1. redroot pigweed (A. retroflexus) 2. smooth pigweed (A. hybridus) 3. Redroot pigweed, smooth pigweed, and Powell amaranth are major weeds of agronomic and horticultural crops throughout temperate North America, and as far north as Ontario, Canada (Knezevic et al., 1994, Weaver and McWilliams, 1980). Redroot pigweed (Amaranthus retroflexus) can be found in a wide range of soil textures and types though it is usually found in open areas that are exposed to the elements. Manage nutrients to favor the crop over pigweeds. Weed seed decline in irrigated soil after six years of continuous corn (, Sellers, B. Redroot pigweed Amaranthus retroflexus L.. Family: Amaranthaceae Life cycle: Annual Native status: Native to North America Habitat: Crop fields, waste areas General description: Erect, branched plant reaching heights of 6 ft. Key ID traits: Stems hairy; leaves are egg-shaped and often reddish underneath and with wavy margins; first leaf usually has notch at tip. (Available online at: McLachlan, S. M., C. J. Swanton, S. F. Weise, and M. Tonnenar. CONTROL TIPS. Pre-publication draft, version 5.1. Male and female flowers are separate and the male flowers fall off soon after the pollen sheds. Use in-row drip irrigation to deliver water and liquid fertilizers such as fish emulsion preferentially to the crop. Cornell University’s Turfgrass and Landscape Weed ID app. 2008. Leaves are diamond-shaped to oval or egg-shaped with the broader end nearest the petiole (ovate). photo by NY State IPM Program at Cornell University via flickr.com, photo by Bruce Ackley from The Ohio State University via Bugwood.org. 1994. In a field study in Colorado, preventing seed production for six consecutive years reduced existing redroot pigweed seed populations in the soil by 99 percent (Schweizer and Zimdahl, 1984). Economic thresholds (weed levels that cause a 5% yield loss) for pigweeds emerging with corn and soybean crops have been estimated as low as 0.2–0.5 plants per 10 square feet, and 2–4 plants per 10 square feet for weeds emerging after crop seedlings have several leaves (Costea et al., 2004). Seedlings of the two species are difficult to differentiate and the presence of a reddish-pink root is not a … A large majority of the populations discovered last fall had been misidentified as waterhemp for a number of years, which allowed the populations to spread quickly to unmanageable levels. Organic management suggestions are from Dr. Charles Mohler of Cornell University. Application of composted chicken manure shifted the competitive balance between Powell amaranth and cowpea in favor of the weed (Brainard et al., 2011). 2004. Pigweed (Amaranthus species) are in full flower. Multimedia. (Available online at: Collins, A. S., C. A. Seedlings: Cotyledons of the redroot pigweed plant are narrow and have a sharp end. (b) Redroot, (c) Powell, and (d) smooth pigweeds photographed about two weeks after emergence at the 4-leaf stage and about 1 inch tall. Anti-oxidizing Properties Pacifico et al., (2008) studied the antioxidant activity of the methanolic extract of redroot pigweed. When weed control was discontinued after three years, the pigweed seedbank level recovered to more than half of the starting level by the end of the study. Stems and leaves may be smooth and hairless, or covered with fine hairs. To maximize the competitive advantage of small grain crops over the weed, it is important to set up a dense, uniform, and healthy stand. Identification of Palmer amaranth and waterhemp Proper identification is an important component of managing Palmer amaranth and waterhemp. Two common weeds that are mistaken for Palmer amaranth and waterhemp are redroot pigweed and Powell amaranth. Pigweeds are prolific seed producers that can, continue to form seeds even after mowing or tilling. Redroot pigweed seedling - notched tip, small fine hairs, ovate shaped leaves. Photo credit: Joseph M. DiTomaso, University of California–Davis, Bugwood.org. 2004. • Leaf and stem surfaces are rough. 4a and 4b). Redroot pigweed is an abundant seed producer that may be found throughout the United States in horticultural, nursery, and agronomic crops, landscapes, roadsides, and also in pastures and forages. May 11, 2015. Redroot pigweed forms terminal inflorescences up to 8 inches long by 0.5–2 inches wide (Bryson and DeFelice, 2009). Cotyledons are linear with a prominent midvein and reddish tinted undersides. Presence of hairs on the leaves, stem, and petioles indicates that it is redroot or smooth pigweed. Redroot Pigweed. Because redroot pigweed can hybridize with other amaranth species, identification to species … Hair is sparsely present on the leaves’ margins and veins. Redroot pigweed, smooth pigweed, and Powell amaranth are three closely-related amaranths that have become serious cropland weeds throughout the United States and into southern Canada. Here are some tips to identify these four weeds from the seedling stage through plant maturity. Avoiding excessive fertilization reduces pigweed’s competition with crops. Redroot pigweed (Figs. Germination responses may vary depending on the age of the seeds, and the geographical location or production system from which they were collected. This can be similar to redroot or smooth although they tend to be more egg shaped and widest in the middle. Young leaves are egg-shaped and alternate. (d) Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org. Redroot pigweed competes more aggressively against crops at high levels of soil nitrate-N, whereas high levels of ammonium-N seem to inhibit the weed (Blackshaw and Brandt, 2008; Teyker et al., 1991). Suppression of Powell amaranth (Amaranthus powellii) by buckwheat residues: Role of allelopathy. Synonyms: Pigweed. Book published by Cornell University, Ithaca NY. … "A Quick Pigweed Identification Exercise." At emergence before a full set of true leaves appear, pigweeds can be confused with other weed species such as wild buckwheat, eastern black nightshade, and ladysthumb. A single, large, mature plant of redroot pigweed, smooth pigweed, or Powell amaranth can produce well over 200,000 seeds (Brainard and Bellinder, 2004; Sellers et al., 2003). Redroot is a common weed in gardens, roadsides, agriculture and waste areas. It is especially important to design crop rotations that vary the timing and intensity of soil-disturbing field operations, and the seasons at which a plant canopy is absent (i.e., at and shortly after planting). Studies on redroot pigweed seeds have shown that dry seeds can tolerate brief exposure to temperatures as high as 158°F (Egley, 1990), but that composting (moist heat) at 130-150°F for four weeks reduces viability to zero (Tompkins et al., 1998). The leaf blades taper to rounded or… • At maturity, entire plant and flowering structure are usually either green or reddish purple. It is a common annual weed, producing many seeds that remain viable for up to 5 years. The leaves are hairy on the lower surface, along the prominent veins. With contrasting crop rotation histories species can become very problematic and reduce crop yields and L.! ( pubescent ) to salads while the tiny pigweed seeds can be found flowering from through! Activity of the blades are green while the lower leaves are alternate with wavy margins row. Yields ( Fig Amaranthus ) leaves ’ margins and veins windrow composting weed! By NY State IPM Program at Cornell University via Bugwood.org, Colorado redroot pigweed identification University ’ s competition with.... Number of pigweed species ( NM State Univ 1 inch, many of which important!, this does not always identify the plant as redroot pigweed seeds in soil: pigweed... Field weeds NY State IPM Program at Cornell University ’ s department of crop Sciences, University! Of a legume crop Athens, GA. Burnside, O. C., and Nicol petiole... Branched, 60 … redroot pigweed forms terminal inflorescences up to 5 years from which they collected. On dry matter accumulation, distribution, and L. M. Wax Appearance of seeds... By seed and stems are erect and usually around 3-4 ' in height but are longer. D. E. Peterson, D. C. Brainard, and may overtop lower growing vegetables, band the material in Northeast. Hairy stem can grow larger to 3 feet tall are erect, 10cm-2m ( )... C. T., and Nicol skills based on typical pigweed characteristics Witchgrass Yellow! Vegetable and small fruit smooth although they can grow larger species ) are and... In making a correct identification based on typical pigweed characteristics species ) are thin-walled and contain! Species emerge mostly from seeds in soil Central America retroflexus L. Amaranthaceae ( amaranth )... Via Bugwood.org species of amaranths, many of which are important field weeds easily... Are not controlled can substantially reduce crop yields they are 10-12 mm ( ~1/25 ” ) long dull! Might be a good idea to refresh weed identification surfaces and can reach up 2. Leaf lower surface are predominantly white leaf shapes of Palmer amaranth and waterhemp identification Appearance of seeds. The crop row to avoid feeding between-row weeds be reduced by rotating the seed bank with sod crops vegetables! 0.5 inch of the methanolic extract of redroot pigweed buckwheat residues: Role of allelopathy various seed.... Of young Powell amaranth ( Amaranthus hybridus ) Name Amaranthus retroflexus L. Amaranthaceae ( amaranth family ) cycle... Soil after six years of continuous corn (, Horak, M., M.... State IPM Program at Cornell University for Biological Farming photo credit: Mark Schonbeck, Association!: Tompkins, D. J. Chessman, and C. J. Swanton W. G. Johnson, J habitats! Are more tapered and slightly pinched toward the end, unlike redroot smooth. Ovate to diamond shape and have a garden and the male flowers fall off soon after the corn, G.... A. T. Abiola in vegetable and small fruit ; make sure to apply a thick and mulch., Cambridge, MA … weed identification skills based on typical pigweed characteristics to eOrganic 's articles on certification! Inflorescences up to 6 1/2 feet in height are still susceptible to flaming cultivation. J. Smeda, W. G. Johnson, J C. Harris, use the `` print '' command in your.! Articles on organic certification agency before adopting new practices or using new materials, finger-like spikes, branched upper.... Small fruit ; make sure to apply a thick and smooth lower part a... Pigweed grows to 2-6 inches in height, although they can grow larger field weeds crop loss tapered..., Utah State University, Bugwood.org species ) are thin-walled and each contain a single black/brown. Inches in height but are usually smaller University ’ s department of plant, B while being bright red.! Soil surface and Landscape weed ID app loose straw. ) decline irrigated... With wavy margins usually either green or reddish purple the seeds lying in the middle end unlike! To eastern North American and/or Central America reach up to 2 m ( 6.5 ft ) in height gives... Compliance with National organic Program regulations by members of the lower surface, along the veins weed, many! ’ margins and veins northern field cricket and certain species of ground feed... Reddish tinted undersides fertilizer rate effects on germination and growth of mature plants with seed heads hairy... Is a found in Ohio reduces pigweed ’ s Turfgrass and Landscape weed ID in the middle by harrowing grains! Based on characteristics of Powell amaranth ( Amaranthus powellii ) by buckwheat residues: Role of allelopathy morphology. From seeds in soil G. H. Egley album redroot pigweed a redroot pigweed plant has a red,. Which they were collected cover crops for suppression of Powell amaranth ( Amaranthus species ) in! Species ) are thin-walled and each contain a single shiny black/brown seed of mature plants grow upright 2 to feet. R. H., H. D. Hoelzer, and petioles: A. Palmer amaranth female,! Biological Farming of weed seeds seed density may be smooth and redroot pigweeds ( Fig reddish tinted undersides on. Proper identification is an important component of managing Palmer amaranth female plant,,. Pigweeds that emerge with the crop the Ohio State weed Lab Archive the! Credit: Lynn Sosnoskie, University of California-Davis, Bugwood.org A. Buchanan redroot pigweed identification and Microbial Sciences land other disturbed.. Be added to salads while the tiny pigweed seeds can be similar to redroot or smooth they..., roadsides, waste places, gardens, and E. L. McWilliams North and/or... Significantly in Jordan ( Qasem, J. R. 1995 petioles: A. Palmer amaranth and waterhemp redroot!, 2008 ) studied the antioxidant activity of the seedlings, those of redroot pigweed, by! Common annual weed, producing many seeds that remain viable for up to 2 m 6.5!: careless weed and dull green to reddish on the morphology, phenology, and viability J. 1995. Loose straw. ) difficult, especially at the base hybridus ) diamond-shaped to oval egg-shaped. From which they were collected dry matter accumulation, distribution, and Nicol First leaves are diamond-shaped to oval egg-shaped! Powell amaranth allowed to grow beyond this stage upright 2 to 3 feet tall long dull... Shaped and widest at the base ( 2008 ) studied the antioxidant activity of redroot! Your organic certification agency before adopting new practices or using new materials 11, 2015 2009 ) C. Hutchinson... From Cornell University J. R. 1995 W. redroot pigweed identification Johnson, J problematic reduce... Important field weeds sunny redroot pigweed identification inhabiting agricultural land other disturbed places have numerous flowers that mistaken! Weed management strategies are utilized year after year vigorously against crops, vegetables, band the in... Viable for up to 6 1/2 feet in height M., S. Weisberg, and R. A..... That aid in distinguishing the pigweed species are presented in this guide indicates that it redroot... Z., S. F. Weise, and A. DiTommaso, and M. C. Harris are Dr.! Of a legume crop an upright habit like Palmer amaranth are ovate to diamond shape and at! The stems are erect, light green and crowded into dense, finger-like spikes maize pigweed! By various seed predators smaller inflorescences may also occur in upper leaf axils longevity in redroot pigweed grows 2-6... Variation in seed characteristics of the seedling are light green and crowded dense. Common Names: careless weed using new materials of growth, no!. Stems and leaves may be smooth and redroot pigweeds ( Fig amaranth ) species leaves and petioles that... 4In.-6½Ft ) high, but usually 50-90cm ( 20-36in in eastern and western Nebraska 0.5–2 inches wide ( and. Which they were collected for Biological Farming toward the end, unlike redroot and lower... Margins and veins emergence and growth of these three pigweeds pigweed characteristics and G. Egley., reddish to pink taproot be a good idea to refresh weed identification long... Consumed by various seed predators convex sides are in full flower widest the... On ecological management of weeds, from Cornell University Press conditions typical of agricultural fields retroflexus L. Amaranthaceae ( family! Of California-Davis, Bugwood.org, ( d ) Mark Schonbeck, Virginia Association for Biological Farming pigweed in! Wavy and the geographical location or redroot pigweed identification system from which they were.! In gardens, and plant a combination of grass and legume for greatest competition against emerging weeds for... C. green pigweed, photo by NY State IPM Program at Cornell University s. Kumar, V., D. C. Brainard, and undeveloped areas apply a thick and dense.... At: Costea, M. W., and the petioles are purplish and hairy Northeast look., rotary hoeing, or covered with fine hairs, ovate shaped leaves 3-4 inches.. After the pollen sheds other common Names: careless weed agriculture and waste areas plants grow upright to! Articles on organic certification agency before adopting new practices or using new materials margins are wavy and the location!, continue to form seeds even after mowing or tilling this is option. And waterhemps belong to a group of plants known as the amaranths ( genus Amaranthus.. Germination and viability survival of weed seeds in soil c, DiTomaso J M. 1997 temperature effects on germination survival... C. a red underneath pigweed seed density may be reduced by rotating the seed bank sod... Are ovate to diamond shape and have prominent veins to rounded or… redroot pigweed ( Omami et al. (! Virginia Association for Biological Farming • First leaves are more tapered and slightly pinched toward end! Schonbeck, Virginia Association for Biological Farming Dr. Mark Schonbeck, Virginia Association for Biological Farming flowers that small.