Velvetleaf

Abutilon theophrasti Medik.

Images above: Upper Left: Velvetleaf seedling (Antonio DiTommaso, Cornell University). Upper Right: Velvetleaf young plant (Antonio DiTommaso, Cornell University). Bottom left: Velvetleaf flower (Robert Nurse). Bottom right: Velvetleaf mature capsules (Scott Morris, Cornell University). 

Identification

Other common names:  butter-print, butter-weed, pie-marker, Indian mallow, velvet-weed, Indian hemp, cotton-weed, buttonweed, wild cotton, elephant ear, chingma, velvet-leaf butterprint

Family:  mallow family, Malvaceae

Habit:  Tall, erect, summer annual herb.

Description:  The stem of the seedling is hairy.  Cotyledons are heart-shaped, 0.13-0.5” (0.3-1.3 cm) long, and hairy on all surfaces, including the edge.  The first true leaves are alternate, heart-shaped, covered with soft hairs on both surfaces, and have blunt teeth along the edges.  Mature plants are 2-7 ft (0.6-2.1 m) tall, with hairy stems that often branch towards the top of the plant.  Leaves are alternate, densely covered in soft, fine hairs, and heart shaped with a tapered tip.  Each leaf is 4-8” (10-20 cm) long and wide, with a petiole also reaching 4-8” (10-20 cm) in length.  Leaf edges are bluntly toothed.  Prominent veins radiate from the point of leaf stalk attachment.  Leaf and stem tissue give off a distinctive odor when crushed.  The root system is a shallow, branching, white taproot.  The flowers are yellow to yellow-orange and grow from the upper leaf axils on 1-2” (2.5-5 cm) long stalks.  Each flower is 0.6-1” (1.5-2.5 cm) wide and has five green sepals and five shallowly notched petals.  Flowers are replaced by circular, cup-shaped capsules composed of a ring of flattened, pointy tipped seedpods.  The capsules are light green when young and become brown to black as they mature.  Mature capsules may remain on dead stems throughout the winter.  Each capsule contains 15-45 grey-brown, kidney to heart-shaped seeds.  Each seed is 0.04-0.06” (0.1-0.15 cm) thick and 0.08-0.11” (0.2-0.3 cm) long and wide.

Similar species:  Common mallow (Malva neglecta Wallr.), prickly sida (Sida spinosa L.), and Venice mallow (Hibiscus trionum L.) seedlings may sometimes be confused with velvetleaf.  The cotyledons of all three species are hairless, however, while those of velvetleaf are covered in fine hairs.  The first true leaves of common mallow are rounded rather than heart-shaped like velvetleaf, while prickly sida true leaves are more oval in shape and have larger teeth than those of velvetleaf.  The first true leaves of Venice mallow are irregularly shaped, and all subsequent leaves are divided into three or more distinct lobes.

Management

Velvetleaf is primarily a pest in long season, spring planted row crops like corn and soybean, and rotating away from these crops helps manage the weed.  Most velvetleaf emerge in the spring, so delaying planting or rotating to a summer planted crop allows destruction of many seedlings by tillage and a reduction in velvetleaf density in the crop.  Also, plants are usually not as competitive in summer planted crops due to more rapid initiation of reproduction in response to shortening day length (Oliver 1979).  Velvetleaf generally does not begin setting seeds until late summer.  Consequently, early harvested crops like winter or spring grains or peas interrupt this weed's life cycle.  In spring/early summer row crops, a good, uniform stand and vigorous crop are critical since crop competition can greatly decrease branching and seed production of velvetleaf (Warwick and Black 1988, Nurse and DiTommaso 2005).

A comparison of several studies on competition between corn and velvetleaf showed that velvetleaf caused little yield loss in years with cool weather of less than 58 °F (14 °C) average temperature during the first two weeks after planting (McDonald et al. 2004).  In years with warm weather after planting, velvetleaf was only moderately competitive if the weather was wet during the period of rapid corn growth (30 to 75 days after planting), but caused large yield losses if the weather was dry during that period.  Thus, early season control of velvetleaf is particularly important in years with warm spring weather.

Velvetleaf seedlings can emerge from deep enough in soil that many will survive tine weeding or rotary hoeing.  Consequently, you should target these operations against the white thread stage.  This may entail more frequent cultivation with these implements than you would use against a more slowly establishing weed like common lambsquarters or redroot pigweed.  Very shallow cultivation that cuts the plant just below or even at the soil surface causes high mortality of both seedlings and larger plants.

Both rodents and insects consume large numbers of velvetleaf seeds on the soil surface (Cardina et al. 1995, Williams et al. 2009), and germinating seeds on the soil surface are prone to drying out before they become rooted.  Consequently, if you have a year with high seed production of this species, avoid fall tillage to allow these mortality factors to operate.  A large percentage of velvetleaf seeds will germinate immediately following burial, so plowing to place surface seeds too deep for successful emergence will eliminate a substantial portion of the surface seed bank (Davis and Renner 2007).  However, seeds that do not immediately germinate will likely persist for many years and emerge following subsequent tillage events (Cardina and Norquay 1997).

Because the seeds are relatively large, velvetleaf can emerge through relatively thick 3-5” (8-13 cm) layers of organic mulch material (Mohler and Teasdale 1993, Mohler unpublished data).  Nonetheless, velvetleaf establishment was consistently suppressed when soybeans were grown in a rye cover crop left on the soil surface without tillage compared to soybeans that were planted after rye was incorporated by tillage (Bernstein et al. 2014).  Velvetleaf seeds are exceptionally resistant to heat (Nishida et al. 1999), and solarization only slightly reduces the survival of velvetleaf seeds (Egley 1983).  However, velvetleaf seeds were sufficiently sensitive to very high heat levels such that they would be completely destroyed by narrow-windrow burning of soybean residues (Norsworthy et al. 2020).

Ecology

Origin and distribution:  Velvetleaf is native to Asia and was introduced to the United States from China as a fiber crop during the colonial era (Spencer 1984).  It subsequently spread throughout the U.S.A. and southern Canada (USDA Plants).  It also has been introduced into Europe (Guglielmone et al. 2000).

Seed weight:  6-10 mg (Hartgerink and Bazzaz 1984), 7-11 mg (Baloch et al 2001), 8.4-10.4 mg (Loddo et al. 2019), 8.9 mg (Garbutt and Bazzaz 1984), 8.9-9.4 mg (Stoller and Wax 1973), 8.9-11.8 mg (Warwick and Black 1986), 9.2 mg (Shergill et al. 2020).

Dormancy and germination:  When shed from the parent plant, 3-62% of velvetleaf seeds are dormant due to a hard seed coat that is impermeable to water (Warwick and Black 1986).  The percentage of hard seeds produced varies greatly between populations (Loddo et al. 2019, Warwick and Black 1986).  Also, seeds produced in a shady environment have thinner seed coats and a substantially lower percentage dormancy (Bello et al. 1995, Nurse and DiTommaso 2005).  As dormant seeds age, the pore where the seed attached to the parent plant eventually cracks open and allows water to enter and germination to proceed (LaCroix and Staniforth 1964).  This leads to sporadic germination over many years.  The seed coat contains germination inhibitors, but these appear to be unimportant in maintaining dormancy in the field (LaCroix and Staniforth 1964).  A few seeds will germinate at 46 °F (8 °C), but germination is best at 75-86 °F (24-30 °C) and declines above 95 °F (35 °C) (Horowitz and Taylorson 1984, Leon and Knapp 2004).  Above 122 °F (50 °C), seed coat permeability increases and so does seed mortality (Horowitz and Taylorson 1984, Nishida 1999).  Temperature fluctuations do not promote germination (Horowitz and Taylorson 1984. Leon and Knapp 2004), but a period of drying at a warm temperature (93 °F or 34 °C) after exposure to moisture does (Horowitz and Taylorson 1984).  Natural chilling of seeds during the winter has little effect on germination (Dorado et al. 2009).  Light does not affect germination of fresh seeds (Horowitz and Taylorson 1984), but promotes germination of seeds that have been buried in the soil (Holm 1972, Stoller and Wax 1974).  Germination of velvetleaf seeds in the soil is inhibited by volatile organic compounds like ethanol and acetaldehyde that are produced during anaerobic respiration (Holm 1972).  This may partially explain why tillage, which vents these compounds to the atmosphere, can prompt a flush of emergence.  Application of nitrate does not increase seed germination (Fawcett and Slife 1978).  The large seeds of velvetleaf require good soil-seed contact to germinate, and consequently germination is best in a fine seedbed (Pareja and Staniforth 1985).

Seed longevity:  Velvetleaf seeds can persist in the soil for several decades (Toole and Brown 1946, Burnside et al. 1996).  Mortality rates for undisturbed seeds range from 11-17% per year over 3-6 year periods (Stoller and Wax 1974, Egley and Chandler 1983, Lueschen and Anderson 1980).  Experiments using locally collected seeds from several midwestern states, however, found an average seed loss of 41-43% over the first year for shallowly buried seeds (Davis et al. 2005, Schutte et al. 2008).  When soil was tilled annually, seed mortality rates of 32-53% per year were observed (Lueschen and Anderson 1980, Buhler and Hartzler 2001).  In a velvetleaf demographic study, Lindquist et al. (1995) found that 71% of the seeds in the seedbank in the previous fall were lost by the following spring.  One year mortality of seeds decreased from an average of 55% at the soil surface to 3% at 6” (16 cm) (Mohler, unpublished data).  Mice consume 31-99% of seeds left on the soil surface over the winter, with mortality rate increasing with the amount of cover (Williams et al. 2009).  Although velvetleaf seeds are highly persistent, a partial draw-down of the seed bank can be achieved over several years if seed production is prevented (Lueschen et al. 1993), and this can result in reduced seedling emergence in the crop (Hartzler 1996).

Season of emergence: Velvetleaf emerges primarily from mid-spring to early summer, but a few seedlings emerge sporadically later in the growing season (Hartzler et al. 1999, Lindquist et al. 1995, Loddo et al. 2019, Masin et al. 2012, Myers et al. 2004, Stoller and Wax 1973, Werle et al. 2014).

Emergence depth:  Seedlings emerge best from the top 0.5-1” (1.3-2.5 cm) while emergence is more variable from the top 2-3” (5-7.5 cm) of soil, and only a few emerge from below 3” (7.5 cm) (Herr and Stroube 1970, Stoller and Wax 1973, Benvenuti et al. 2001, Davis and Renner 2007, Mohler, unpublished data).  Emergence is poor from seeds on the soil surface (Mohler, unpublished data).

Photosynthetic pathway:  C3 (Warwick and Black 1988).

Sensitivity to frost:  Velvetleaf is killed by the first hard frost (Peterson and Thompson 2010).

Drought tolerance:  Velvetleaf is drought tolerant.  Plant growth and reproduction parameters were relatively unaffected when soil moisture was reduced to 50% field capacity, but growth and seed production was severely reduced at 25% field capacity (Mausbach et al. 2022).  In drought conditions it loses the lower leaves, which reduces water use and aids survival to reproduction (Schmidt et al. 2011).  Corn uses water more efficiently than velvetleaf and consequently can grow faster when water is in short supply (Vaughn et al. 2016).

Mycorrhizae:  Velvetleaf is mycorrhizal, and the importance of mycorrhizae for phosphorus nutrition of this species has been demonstrated (Stanley et al. 1993).

Response to fertility:  Velvetleaf growth is highly responsive to fertilization, especially fertilization with N.  Applications of poultry manure compost or blood meal increased productivity up to 320 lb N/A (358 kg/ha) (Little et al 2015).  Adding swine manure at rates of 500-643 lb N/A (560-720 kg/ha) plus 105 lb N/A (118 kg/ha) chemical fertilizer more than doubled seed production relative to 132 lb N/A (148 kg/ha) of chemical fertilizer alone (Liebman et al. 2004).  In a pot experiment, plants increased in size and seed production up to 440-880-440 lb/A N-P-K (493-986-493 kg/ha) (Sugiyama and Bazzaz 1997).  Seedlings from plants grown in highly fertile conditions are larger and more competitive than those from plants grown at lower fertility (Parrish and Bazzaz 1985, Wulff and Bazzaz 1992).

Soil physical requirements:  Velvetleaf tolerates poor drainage (USDA Plants) and a wide range of soil textures.

Response to shade:  Velvetleaf is moderately shade tolerant (Warwick and Black 1988).  Shade at 30% only slightly decreased growth, but 76% shade reduced plant weight and seed production by 88% or more (Bello et al. 1995).  Velvetleaf growth and seed production declined linearly as shading from a corn leaf canopy increased (Teasdale 1998).  Because shade and crop competition have relatively small effects on plant height (Jordan 1979, Bello et al. 1995), velvetleaf is often able to grow into or over the top of crop canopies.

Sensitivity to disturbance:  Velvetleaf can tolerate up to 75% defoliation at 6 weeks after emergence with little effect on plant size or seed production provided the plants are not shaded (Lee and Bazzaz 1980).  The substantial root system and fibrous stems of large velvetleaf plants make them difficult to uproot with cultivation.

Time from emergence to reproduction:  Velvetleaf flowers in response to short days, so spring emerging individuals require more time to flower than summer emerging plants.  Spring emerging plants in Wisconsin and Ontario flowered 11-12 weeks after emergence (Doll 2002, Warwick and Black 1986).  Flowers pollinate the day they open.  A few seeds become viable 12 days after flowering and essentially all are viable within 15 days, but capsules do not open to disperse seeds until 18-23 days after flowering (Kordbacheh et al. unpublished data).  Flowering and seed production continue until frost (Warwick and Black 1988).

Pollination:  The species is primarily self-pollinated (Warwick and Black 1988), but some cross pollination by insects probably occurs.

Reproduction:  The number of seeds produced is proportional to the weight of the plant (Nurse and DiTommaso 2005, Teasdale 1998).  Plants typically produce 70-200 capsules, each containing 35-45 seeds (Warwick and Black 1988).   Plants grown without crop competition typically produce 700-17,000 seeds (Warwick and Black 1988) but much lower seed production has also been observed (Lindquist et al.1995).  Crop competition can substantially reduce seed production (Lindquist et al. 1995, Nurse and DiTommaso 2005), but velvetleaf growing in corn can still produce 1,000 to 2,000 seeds/plant in favorable circumstances (Lindquist and Mortensen 1998, Teasdale 1998, Zanin and Sattin 1988).  Over 7 site-years, on average 30% of velvetleaf seeds were shattered by soybean harvest although there was considerable variation among sites (Schwartz-Lazaro et al. 2021).

Dispersal:  Much feed corn is contaminated with velvetleaf seeds.  These pass readily through the digestive tract of livestock and are spread with manure (Mt. Pleasant and Slather 1994).  Seeds also pass intact through the guts of some birds or are regurgitated after being retained for several days, so dispersal by birds seems likely (Proctor 1968).  Dispersal also occurs with soil clinging to tires and tillage implements (Warwick and Black 1988).  Combines probably also spread the weed between fields and farms.

Common natural enemies:  Scentless plant bugs (Niesthrea louisianica) attack young pods and seeds and can substantially reduce reproduction both by direct damage and by introducing pathogens (Warwick and Black 1988, Kremer and Spencer 1989a, 1989b).  Carabid ground beetles, slugs, cutworms, and especially mice, eat a substantial percentage of the seeds after dispersal (Cardina et al. 1995, Williams et al. 2009).  Verticillium wilt (V. dahlia and V. nigrescens) may greatly reduce seedling density, particularly when plants are shaded by a crop (Lindquist et al. 1995, Hartzler 1996, Warwick and Black 1988).  Fusarium lateritium wilt disease can reduce velvetleaf growth by as much as 86% and result in up to 55% mortality of velvetleaf seedlings (Okalebo et al. 2011).  The fungus Colletotrichum coccodes reduces plant growth and reproduction and has been tested as a biological control agent (DiTomasso and Watson 1995, DiTomasso et al. 1996).  Velvetleaf in organic corn fields in New York are often heavily attacked by a species-specific white fly that greatly damages the leaves, both directly and by introducing a virus.  Damage to the velvetleaf may be so extensive that only a few individuals along the field edges reach maturity (Mohler and DiTommaso, personal observation).

Palatability:  The seeds are eaten as food in China and Kashmere (Spencer 1984).  Some sheep find velvetleaf palatable while others reject it (Marten and Andersen 1975).

Note:  Velvetleaf has allelopathic effects on some crops (Colton and Einhellig 1980).

References:

  • Baloch, H. A., A. DiTommaso, and A. K. Watson.  2001.  Intrapopulation variation in Abutilon theophrasti seed mass and its relationship to seed germinability.  Seed Science Research 11:335-342.
  • Bello, I. A., M. D. A. Owen, and H. M. Hatterman-Valenti.  1995.  Effect of shade on velvetleaf (Abutilon theophrasti) growth, seed production and dormancy.  Weed Technology 9:452-455.
  • Benvenuti, S., M. Macchia, and S. Miele.  2001.  Quantitative analysis of emergence of seedlings from buried weed seeds with increasing soil depth.  Weed Science 49:528-535.
  • Bernstein, E. R., D. E. Stoltenberg, J. L. Posner, and J. L. Hedtcke.  2014.  Weed community dynamics and suppression in tilled and no-tillage transitional organic winter rye-soybean systems.  Weed Science 62:125-137.
  • Buhler, D. D., and R. G. Hartzler.  2001.  Emergence and persistence of seed of velvetleaf, common waterhemp, woolly cupgrass, and giant foxtail.  Weed Science 49:230-235.
  • Burnside, O. C., R. G. Wilson, S. Weisberg, and K. G. Hubbard.  1996.  Seed longevity of 41 weed species buried 17 years in eastern and western Nebraska.  Weed Science 44:74-86.
  • Cardina, J., and H. M. Norquay.  1997.  Seed production and seed bank dynamics in subthreshold populations of velvetleaf (Abutilon theophrasti) populations.  Weed Science 45:85-90.
  • Cardina, J., H. M. Norquay, B. R. Stinner, and D. A. McCartney.  1995.  Post-dispersal predation of velvetleaf (Abutilon theophrasti) seeds.  Weed Science 44:534-539.
  • Colton, C. E., and F. A. Einhellig.  1980.  Allelopathic mechanisms of (Abutilon theophrasti Medic., Malvaceae) on soybean.  American Journal of Botany 67:1407-1413.
  • Davis, A. S., and K. A. Renner.  2007.  Influence of seed depth and pathogens on fatal germination of velvetleaf (Abutilon theophrasti) and giant foxtail (Setaria faberi).  Weed Science 55:30-35.
  • Davis, A. S., J. Cardina, F. Forcella, G. A. Johnson, G. Kegode, J.  L. Lindquist, E. C. Luschei, K. A. Renner, C. L. Sprague, and M. M. Williams II.  2005.  Environmental factors affecting seed persistence of annual weeds across the U.S. corn belt.   Weed Science 53:860-868.
  • DiTommaso, A., and A. K. Watson.  1995.  Impact of a fungal pathogen, Colletotrichum coccodes on growth and competitive ability of Abutilon theophrasti.  New Phytologist 131:51-60.
  • DiTommaso, A., A. K. Watson, and S. G. Hallett.  1996.  Infection by the fungal pathogen Colletotrichum coccodes affects velvetleaf (Abutilon theophrasti)-soybean competition in the field.  Weed Science 44:924-933.
  • Doll, J.  2002.  Knowing when to look for what: Weed emergence and flowering sequences in Wisconsin. Weed Science University of Wisconsin. https://extension.soils.wisc.edu/wp-content/uploads/sites/68/2016/07/Doll-2.pdf
  • Dorado, J., C. Fernández-Quintanilla, and A. C. Grundy.  2009.  Germination patterns in naturally chilled and nonchilled seeds of fierce thornapple (Datura ferox) and velvetleaf (Abutilon theophrasti).  Weed Science 57:155-162.
  • Egley, G. H.  1983.  Weed seed and seedling reductions by soil solarization with transparent polyethylene sheets.  Weed Science 31:404-409.
  • Egley, G. H., and J. M. Chandler.  1983.  Longevity of weed seeds after 5.5 years in the Stoneville 50-year buried seed study.  Weed Science 31:264-270.
  • Fawcett, R. S., and F. W. Slife.  1978.  Effects of field application of nitrate on weed seed germination and dormancy.  Weed Science 26:594-596.
  • Garbutt, K., and F. A. Bazzaz.  1984.  The effects of elevated CO2 on plants. III. Flower, fruit and seed production and abortion.  New Phytologist 98:433-446.
  • Guglielmone, L., C. E. Jenner, J. A. Walsh, E. Ramasso, D. Marian, and P. Roggero.  2000.  An unusual isolate of turnip mosaic potyvirus from Abutilon theophrasti in Piedmont, Italy.  Phytoparasitica 29:148-152.
  • Hartgerink, A. P., and F. A. Bazzaz.  1984.  Seedling scale environmental heterogeneity influences individual fitness and population structure.  Ecology 65:198-206.
  • Hartzler, R. G., D. D. Buhler, and D. E. Stoltenberg.  1999.  Emergence characteristics of four annual weed species.  Weed Science 47:578-584.
  • Hartzler, R. G.  1996.  Velvetleaf (Abutilon theophrasti) population dynamics following a single year’s seed rain.  Weed Technology 10:581-586. 
  • Herr, D. E., and E. W. Stroube.  1970.  Velvetleaf control as influenced by herbicide placement and seed depth.  Weed Science 18:459-461.
  • Holm, R. E.  1972.  Volatile metabolites controlling germination in buried weed seeds.  Plant Physiology 50:293-297.
  • Horowitz, M., and R. B. Taylorson.  1984.  Hardseededness and germinability of velvetleaf (Abutilon theophrasti) as affected by temperature and moisture.  Weed Science 32:111-115.
  • Jordan, J. L.  1979.  The growth habit of Pennsylvania smartweed and velvetleaf.  Proceedings of the North Central Weed Control Conference 34:48.
  • Kremer, R. J., and N. R. Spencer.  1989a.  Impact of a seed-feeding insect and microorganisms on velvetleaf (Abutilon theophrasti) seed viability.  Weed Science 37:211-216.
  • Kremer, R. J., and N. R. Spencer.  1989b.  Interaction of insects, fungi, and burial on velvetleaf (Abutilon theophrasti) seed development.  Weed Technology 3:322-328.
  • LaCroix, L. J., and D. W. Staniforth.  1964.  Seed dormancy in velvetleaf.  Weeds 12:171-174.
  • Lee, T. D., and F. A. Bazzaz.  1980.  Effects of defoliation and competition on growth and reproduction in the annual plant Abutilon theophrasti.  Journal of Ecology 68:813-821.
  • Leon, R. G., and A. D. Knapp.  2004.  Effect of temperature on the germination of common waterhemp (Amaranthus tuberculatus), giant foxtail (Setaria faberi), and velvetleaf (Abutilon theophrasti).  Weed Science 52:67-73.
  • Liebman, M., F. D. Menalled, D. D. Buhler, T. L. Richard, D. N. Sundberg, C. A. Cambardella, and K. A. Kohler.  2004.  Impacts of composted swine manure on weed and corn nutrient uptake, growth, and seed production.  Weed Science 52:365-375.
  • Lindquist, J. L., B. D. Maxwell, D. D. Buhler, and J. L. Gunsolus.  1995.  Velvetleaf (Abutilon theophrasti) recruitment, survival, seed production and interference in soybean (Glycine max).  Weed Science 43:226-232.
  • Lindquist, J. L., and D. A. Mortensen.  1998.  Tolerance and velvetleaf (Abutilon theophrasti) suppressive ability of two old and two modern corn (Zea mays) hybrids.  Weed Science 46:569-574.
  • Little, N. G., C. L. Mohler, Q. M. Ketterings, and A. DiTommaso.  2015.  Effects of organic nutrient amendments on weed and crop growth.  Weed Science 63:710-722.
  • Loddo, D., et al. (13 junior authors).  2019.  Variability in seedling emergence for European and North American populations of Abutilon theophrasti.  Weed Research 59:15-27.
  • Lueschen, W. E., and R. N. Andersen.  1980.  Longevity of velvetleaf (Abutilon theophrasti) seeds in soil under agricultural practices.  Weed Science 28:341-346.
  • Lueschen, W. E., R. N. Andersen, T. R. Hoverstad, and B. K. Kanne.  1993.  Seventeen years of cropping systems and tillage affect velvetleaf (Abutilon theophrasti) seed longevity.  Weed Science 41:82-86.
  • Marten, G. C., and R. N. Andersen.  1975.  Forage nutritive value and palatability of 12 common annual weeds.  Crop Science 15:821-827.
  • Masin, R., D. Loddo, S. Benvenuti, S. Otto, and G. Zanin.  2012.  Modeling weed emergence in Italian maize fields.  Weed Science 60:254–259.
  • Mausbach J, S. Irmak, P. Chahal, D. Sarangi, and A. J. Jhala.  2022.  Effect of degree of water stress on growth and fecundity of velvetleaf (Abutilon theophrasti) using soil moisture sensors. Weed Science 70:698–705.
  • McDonald, A. J., S. J. Riha, and C. L. Mohler.  2004.  Mining the record: historical evidence for climatic influences in maize – Abutilon theophrasti competition.  Weed Research 44:439-445.
  • Mohler, C. L., and J. R. Teasdale.  1993.  Response of weed emergence to rate of Vicia villosa Roth and Secale cereale L. residue.  Weed Research 33:487–499.
  • Myers, M. M., W. S. Curran, M. J. VanGessel, D. D. Calvin, D. A. Mortensen, B. A. Majek, H. D. Karsten, and G. W. Roth.  2004.  Predicting weed emergence for eight annual species in the northeastern United States.  Weed Science 52:913-919.
  • Mt. Pleasant, J., and K. J. Slather.  1994.  Incidence of weed seed in cow (Bos pp.) manure and its importance as a weed source for crop land.  Weed Technology 8:304-310.
  • Nishida, T., S. Kurokawa, S. Shibata, and N. Kitahara.  1999.  Effect of duration of heat exposure on upland weed seed viability.  Journal of Weed Science and Technology 44:59-66.
  • Norsworthy, J. K., J. K. Green, T. Barber, T. L. Roberts, M. J. Walsh.  2020.  Seed destruction of weeds in southern US crops using heat and narrow-windrow burning. Weed Technology 34:589–596.
  • Nurse, R. E., and A. DiTommaso.  2005.  Corn competition alters the germinability of velvetleaf (Abutilon theophrasti) seeds.  Weed Science 53:479-488.
  • Okalebo, J., G. Y. Yuen, R. A. Drijber, E. E. Blankenship, C. Eken, and J. L. Lindquist.  2011.  Biological suppression of velvetleaf (Abutilon theophrasti) in an eastern Nebraska soil.  Weed Science 59:155-161.
  • Oliver, L. R.  1979.  Influence of soybean (Glycine max) planting date on velvetleaf (Abutilon theophrasti) competition.  Weed Science 27:183-188.
  • Pareja, M. R., and D. W. Staniforth.  1985.  Seed-soil microsite characteristics in relation to weed seed germination.  Weed Science 33:190-195.
  • Parrish, J. A. D., and F. A. Bazzaz.  1985.  Nutrient content of Abutilon theophrasti seeds and the competitive ability of the resulting plants.  Oecologia (Berlin) 65:247-251.
  • Peterson, D., and P. Thompson.  2010.  Velvetleaf growth habits and characteristics.  K-State Extension, Agronomy e-Updates 236:1-4.  http://www.agronomy.ksu.edu/extension/p.aspx?tabid=58#mar10
  • Proctor, V.  1968.  Long-distance dispersal of seeds by retention in digestive tract of birds.  Science 160:321-322.
  • Schmidt, J. J., E. E. Blankenship, and J. L. Lindquist.  2011.  Corn and velvetleaf (Abutilon theophrasti) transpiration in response to drying soil.  Weed Science 59:50-54.
  • Schutte, B. J., A. S. Davis, K. A. Renner, and J. Cardina.  2008.  Maternal and burial environment affects seed mortality of velvetleaf (Abutilon theophrasti) and giant foxtail (Setaria faberi).  Weed Science 56:834-840.
  • Schwartz-Lazaro, L. M., L. S. Shergill, J. A. Evans, M. V. Bagavathiannan, S. C. Beam, M. D. Bish, J. A. Bond, K. W. Bradley, W. S. Curran, A. S. Davis, W. J. Everman, M. L. Flessner, S. C. Haring, N. R. Jordan, N. E. Korres, J. L. Lindquist, J. K. Norsworthy, T. L. Sanders, L. E. Steckel, M. J. VanGessel, B. Young, and S. B. Mirsky.  2021.  Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: Broadleaf species.  Weed Science 69:95–103.
  • Shergill, L. S., K. Bejleri, A. Davis, and Mirsky S. B.  2020.  Fate of weed seeds after impact mill processing in midwestern and mid-Atlantic United States.  Weed Science 68:92–97.
  • Spencer, N. R.  1984.  Velvetleaf, Abutilon theophrasti (Malvaceae), history and economic impact in the United States.  Economic Botany 38:407-416.
  • Stanley, M. R., R. T. Koide, and D. L. Shumway.  1993.  Mycorrhizal symbiosis increases growth, reproduction and recruitment of Abutilon theophrasti Medic. in the field.  Oecologia 94:30-35.
  • Stoller, E. W., and L. M. Wax.  1973.  Periodicity of germination and emergence of some annual weeds.  Weed Science 21:574-580.
  • Stoller, E. W., and L. M. Wax.  1974.  Dormancy changes and fate of some annual weed seeds in the soil.  Weed Science 22:151-155.
  • Sugiyama, S., and F. A. Bazzaz.  1997.  Plasticity of seed output in response to soil nutrients and density in Abutilon theophrasti: implications for maintenance of genetic variation.  Oecologia 112:35-41.
  • Toole, E. H., and E. Brown.  1946.  Final results of the Duvel buried seed experiment.  Journal of Agricultural Research 72:201-210.
  • Teasdale, J. R. 1998.  Influence of corn (Zea mays) population and row spacing on corn and velvetleaf (Abutilon theophrasti) yield.  Weed Science 46:447-453.
  • USDA Plants Database, Natural Resources Conservation Service.  http://plants.usda.gov
  • Vaughn, L. G., M, L. Bernards, T, J. Arkebauer, and J. L. Lindquist.  2016.  Corn and velvetleaf (Abutilon theophrasti) growth and transpiration efficiency under varying water supply.  Weed Science 64:596-604.
  •  Warwick, S., I., and L. D. Black.  1986.  Genecological variation in recently established populations of Abutilon theophrasti (velvetleaf).  Canadian Journal of Botany 64:1632-1643.
  • Warwick, S. I., and L. D. Black.  1988.  The biology of Canadian weeds. 90. Abutilon theophrasti.  Canadian Journal of Plant Science 68:1069-1085.
  • Werle, R., L. D. Sandell, D. D. Buhler, R. G. Hartzler, and J. L. Lindquist.  2014.  Predicting emergence of 23 summer annual weed species.  Weed Science 62:267-279.
  • Williams, C. L., M. Liebman, P. R. Westerman, J. Borza, D. Sundberg, and B. Danielson.  2009.  Over-winter predation of Abutilon theophrasti and Setaria faberi seeds in arable land.  Weed Research 49:439–447.
  • Wulff, R. D., and F. A. Bazzaz.  1992.  Effect of the parental nutrient regime on the growth of the progeny in Abutilon theophrasti (Malvaceae).  American Journal of Botany 79:1102-1107.
  • Zanin, G., and M. Sattin.  1988.  Threshhold level and seed production of velvetleaf (Abutilon theophrasi Medicus) in maize.  Weed Research 28:347-352.