Browsing by Author "Everman, Wesley J."

Now showing 1 - 5 of 5
  • Thumbnail Image
    Current outlook and future research needs for harvest weed seed control in North American cropping systems
    Shergill, Lovreet S.; Schwartz-Lazaro, Lauren M.; Leon, Ramon; Ackroyd, Victoria J.; Flessner, Michael L.; Bagavathiannan, Muthukumar V.; Everman, Wesley J.; Norsworthy, Jason K.; VanGessel, Mark J.; Mirsky, Steven B. (2020-12)
    Harvest weed seed control (HWSC) comprises a set of tools and tactics that prevents the addition of weed seed to the soil seed bank, attenuating weed infestations and providing a method to combat the development and spread of herbicide-resistant weed populations. Initial HWSC research efforts in North America are summarized and, combined with the vast area of crops suitable for HWSC, clearly indicate strong potential for this technology. However, potential limitations exist that are not present in Australian cropping systems where HWSC was developed. These include rotations with crops that are not currently amenable to HWSC (e.g. corn), high moisture content at harvest, untimely harvest, and others. Concerns about weeds becoming resistant to HWSC (i.e. adapting) exist, as do shifts in weed species composition, particularly with the diversity of weeds in North America. Currently the potential of HWSC vastly outweighs any drawbacks, necessitating further research. Such expanded efforts should foremost include chaff lining and impact mill commercial scale evaluation, as this will address potential limitations as well as economics. Growers must be integrated into large-scale, on-farm research and development activities aimed at alleviating the problems of using HWSC systems in North America and drive greater adoption subsequently. (c) 2020 Society of Chemical Industry
  • Thumbnail Image
    Harvest Weed Seed Control: An Integrated Weed Management Strategy for Organic and Conventional Production Systems
    Haring, Steven C. (Virginia Tech, 2017-09-07)
    Harvest weed seed controls (HWSC) destroy weed seeds that are retained by the plant at crop harvest, which would typically be spread by the harvester along with other field residues. HWSC exploits coincidental maturity between crops and weeds, so an experiment was designed to collect weed seeds as they shatter throughout the growing season and through a simulated harvest delay. This experiment monitored four economically important broadleaf species and two grass species in a soybean (Glycine max (L.) Merr.) field. Results indicated that broadleaf species shattered seed at rates accelerating through the growing season, while grass species shattered more seed early in the growing season. Field experiments in organic and conventional winter wheat (Triticum aestivum L.) fields infested with Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot) compared two HWSC techniques to grower-standard weed management programs in each system, including both no-till and full-till standard treatments in the conventional system. Italian ryegrass populations were monitored, and wheat yield was measured both before and after HWSC application. In both organic and conventional cropping systems, HWSC treatments did not provide better Italian ryegrass control than the grower-standard treatments. The conventional program including tillage boosted Italian ryegrass populations. These results suggest that HWSC treatments did not enhance Italian ryegrass control compared to grower-standard practices in either the organic or conventional systems. Additionally, broadleaf weeds may retain enough seeds to be viable targets for HWSC. Incorporating best practices, such as a timely crop harvest, is key for understanding and optimizing HWSC.
  • Thumbnail Image
    Potential wheat yield loss due to weeds in the United States and Canada
    Flessner, Michael L.; Burke, Ian C.; Dille, J. Anita; Everman, Wesley J.; VanGessel, Mark J.; Tidemann, Breanne; Manuchehri, Misha R.; Soltani, Nader; Sikkema, Peter H. (Cambridge University Press, 2021-12)
    Yield losses due to weeds are a major threat to wheat production and economic well-being of farmers in the United States and Canada. The objective of this Weed Science Society of America (WSSA) Weed Loss Committee report is to provide estimates of wheat yield and economic losses due to weeds. Weed scientists provided both weedy (best management practices but no weed control practices) and weed-free (best management practices providing >90% weed control) average yield from replicated research trials in both winter and spring wheat from 2007 to 2017. Winter wheat yield loss estimates ranged from 2.9% to 34.4%, with a weighted average (by production) of 25.6% for the United States, 2.9% for Canada, and 23.4% combined. Based on these yield loss estimates and total production, the potential winter wheat loss due to weeds is 10.5, 0.09, and 10.5 billion kg with a potential loss in value of US$2.19, US$0.19, and US$2.19 billion for the United States, Canada, and combined, respectively. Spring wheat yield loss estimates ranged from 7.9% to 47.0%, with a weighted average (by production) of 33.2% for the United States, 8.0% for Canada, and 19.5% combined. Based on this yield loss estimate and total production, the potential spring wheat loss is 4.8, 1.6, and 6.6 billion kg with a potential loss in value of US$1.14, US$0.37, and US$1.39 billion for the United States, Canada, and combined, respectively. Yield loss in this analysis is greater than some previous estimates, likely indicating an increasing threat from weeds. Climate is affecting yield loss in winter wheat in the Pacific Northwest, with percent yield loss being highest in wheat-fallow systems that receive less than 30 cm of annual precipitation. Continued investment in weed science research for wheat is critical for continued yield protection.
  • Thumbnail Image
    Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: Broadleaf species
    Schwartz-Lazaro, Lauren M.; Shergill, Lovreet S.; Evans, Jeffrey A.; Bagavathiannan, Muthukumar V.; Beam, Shawn C.; Bish, Mandy D.; Bond, Jason A.; Bradley, Kevin W.; Curran, William S.; Davis, Adam S.; Everman, Wesley J.; Flessner, Michael L.; Haring, Steven C.; Jordan, Nicholas R.; Korres, Nicholas E.; Lindquist, John L.; Norsworthy, Jason K.; Sanders, Tameka L.; Steckel, Larry E.; VanGessel, Mark J.; Young, Blake; Mirsky, Steven B. (2021-01)
    Potential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed-shatter phenology in 13 economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after physiological maturity at multiple sites spread across 14 states in the southern, northern, and mid-Atlantic United States. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate increased at northern latitudes. Amaranthus spp. seed shatter was low (0% to 2%), whereas shatter varied widely in common ragweed (Ambrosia artemisiifolia L.) (2% to 90%) over the weeks following soybean physiological maturity. Overall, the broadleaf species studied shattered less than 10% of their seeds by soybean harvest. Our results suggest that some of the broadleaf species with greater seed retention rates in the weeks following soybean physiological maturity may be good candidates for HWSC.
  • Thumbnail Image
    Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: Grass species
    Schwartz-Lazaro, Lauren M.; Shergill, Lovreet S.; Evans, Jeffrey A.; Bagavathiannan, Muthukumar V.; Beam, Shawn C.; Bish, Mandy D.; Bond, Jason A.; Bradley, Kevin W.; Curran, William S.; Davis, Adam S.; Everman, Wesley J.; Flessner, Michael L.; Haring, Steven C.; Jordan, Nicholas R.; Korres, Nicholas E.; Lindquist, John L.; Norsworthy, Jason K.; Sanders, Tameka L.; Steckel, Larry E.; VanGessel, Mark J.; Young, Blake; Mirsky, Steven B. (2021-01)
    Seed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after maturity at multiple sites spread across 11 states in the southern, northern, and mid-Atlantic United States. From soybean maturity to 4 wk after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased moving north through the states. At soybean maturity, the percent of seed shatter ranged from 1% to 70%. That range had shifted to 5% to 100% (mean: 42%) by 25 d after soybean maturity. There were considerable differences in seed-shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output during certain years.