Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: Grass species

Authors: SCHWARTZ-LAZARO, LAUREN - Louisiana State University Agcenter; SHERGILL, LOVREET - University Of Delaware; EVANS, JEFFERY - University Of Illinois; BAGAVATHIANNAN, MUTHUKUMAR - Texas A&M University; BEAM, SHAWN - Virginia Tech; BISH, MANDY - University Of Missouri; BOND, JASON - Mississippi State University; BRADLEY, KEVIN - University Of Missouri; CURRAN, WILLIAM - Pennsylvania State University; DAVIS, ADAM - University Of Illinois; EVERMAN, WESLEY - North Carolina State University; FLESSNER, MICHAEL - Virginia Tech; HARRING, STEVEN - Virginia Tech; JORDAN, NICHOLAS - University Of Minnesota; KORRES, NICHOLAS - University Of Arkansas; LINDQUIST, JOHN - University Of Nebraska; NORSWORTHY, JASON - University Of Arkansas; SANDERS, TAMEKA - Mississippi State University; STECKEL, LARRY - University Of Tennessee; VAN GESSEL, MARK - University Of Delaware; YOUNG, BLAKE - Texas A&M University; Mirsky, Steven

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2020
Publication Date: 10/26/2020
Citation: Schwartz-Lazaro, L.M., Shergill, L.S., Evans, J.A., Bagavathiannan, M.V., Beam, S.C., Bish, M.D., Bond, J.A., Bradley, K.W., Curran, W.S., Davis, A.S., Everman, W.J., Flessner, M.L., Harring, S.C., Jordan, N.R., Korres, N.E., Lindquist, J.L., Norsworthy, J.K., Sanders, T.L., Steckel, L.E., Van Gessel, M.J., Young, B., Mirsky, S.B. 2020. Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: Grass species. Weed Science. 69(1):104-110.

Interpretive Summary: Harvest weed seed control (HWSC) is a new technology now available to directly control seeds on weeds at time of harvest. The success of harvest weed seed control systems depends upon the retention of seeds of target weed species at harvest. A lot of the weeds in our cropping systems retain their seeds at crop maturity, and during the harvest operation. But the level of seed retention in a species is likely influenced by agroecological and environmental factors. So, in 2016 and 2017, seed shatter of eight economically important grass weed species was assessed in soybean from crop maturity to four weeks after maturity at multiple sites spread across fourteen states in the southern, northern, and mid-Atlantic U.S. Lowest seed shatter was observed in the southern U.S. regions and increased as the states moved further north. At soybean maturity, the percent of seed shatter ranged from 1 to 70% and by 25 days after soybean maturity that range shifted to 0 to 95% seeds retained. The results indicate that the summer annual grass species are likely not ideal candidates for HWSC. This information helps researchers and farmers target the best weed candidates for HWSC.

Technical Abstract: 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. Therefore, in 2016 and 2017, seed shatter of eight economically important grass weed species was assessed in soybean from crop maturity to four weeks after maturity at multiple sites spread across fourteen states in the southern, northern, and mid-Atlantic U.S. From soybean maturity to four weeks after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased as the states moved further north. At soybean maturity, the percent of seed shatter ranged from 1 to 70% and by 25 days after soybean maturity, that range shifted to 0 to 95% (mean: 42%) seeds retained. There was a marginal difference between years and the percent seed retained in relation to the number of days to soybean maturity. The results indicate that the summer annual grass species are likely not ideal candidates for HWSC.