Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: Broadleaf 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; LINQUIST, 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: 10/26/2020
Publication Date: 11/4/2020
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., Linquist, 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 1: Broadleaf species. Weed Science. 69(1):95-103.

Interpretive Summary: Harvest weed seed control (HWSC) is a revolutionary weed management opportunity as it provides the first production scale approach to targeting seeds on mature weed plants. The combine is modified to separate weed seeds from the grain for subsequent management either by pulverizing the seed with an impact mill connected to the combine or banded in narrow rows in the field. However, the success of HWSC systems depends upon the retention of seeds of target weed species at harvest. Therefore, in 2016 and 2017, seed shatter of thirteen economically important broadleaf 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. We found that greater proportion of seeds were retained by weeds in southern latitudes and as states moved further north the seed retention decreased. Overall, the broadleaf species shattered less than ten percent of their seeds by maturity. Our results suggest that some of the broadleaf species with higher rates of seed retention in the weeks following soybean maturity may be good candidates for HWSC. This work will inform growers on which weed species are viable candidates for HWSC in their production systems.

Technical Abstract: 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, the level of seed retention in a species is likely to be influenced by agroecological and environmental factors. Therefore, in 2016 and 2017, seed shatter of thirteen economically important broadleaf 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. Greater proportion of seeds were retained by weeds in southern latitudes and shatter rate increased as states moved further north. Seed shatter of Amaranthus species was low (0 to 2%), whereas for common ragweed it was highly variable (2 to 90%) within a given year 30 days past soybean maturity. Overall, the broadleaf species shattered less than ten percent of their seeds by maturity. Our results suggest that some of the broadleaf species with higher rates of seed retention in the weeks following soybean maturity may be good candidates for HWSC.