Giant Ragweed (Ambrosia trifida) Seed Production and Retention in Soybean and Field Margins

• Published in: Weed technology 2016-03, Vol.30 (1), p.246-253
• Main Authors: Goplen, Jared J, Sheaffer, Craig C, Becker, Roger L, Coulter, Jeffrey A, Breitenbach, Fritz R, Behnken, Lisa M, Johnson, Gregg A, Gunsolus, Jeffrey L
• Format: Article
• Language: English
• Subjects: Crop harvesting; Crop production; Edge effects; Harvest; Harvest weed seed control; Harvesting; Herbicides; Plant development; Retention; Seed banks; Seed collection; Seed dispersal; Seed production; seed retention; Seeds; Soybeans; Stems; Vegetation; Weather; WEED BIOLOGY AND COMPETITION; Weed control; Weeds
• ISSN: 0890-037X; 1550-2740
• DOI: 10.1614/WT-D-15-00116.1

As herbicide-resistant weed populations become increasingly problematic in crop production, alternative strategies of weed control are necessary. Giant ragweed, one of the most competitive agricultural weeds in row crops, has evolved resistance to multiple herbicide biochemical sites of action within the plant, necessitating the development of new and integrated methods of weed control. This study assessed the quantity and duration of seed retention of giant ragweed grown in soybean fields and adjacent field margins. Seed retention of giant ragweed was monitored weekly during the 2012 to 2014 harvest seasons using seed collection traps. Giant ragweed plants produced an average of 1,818 seeds per plant, with 66% being potentially viable. Giant ragweed on average began shattering hard (potentially viable) and soft (nonviable) seeds September 12 and continued through October at an average rate of 0.75 and 0.44% of total seeds per day during September and October, respectively. Giant ragweed seeds remained on the plants well into the Minnesota soybean harvest season, with an average of 80% of the total seeds being retained on October 11, when Minnesota soybean harvest was approximately 75% completed in the years of the study. These results suggest that there is a sufficient amount of time to remove escaped giant ragweed from production fields and field margins before the seeds shatter by managing weed seed dispersal before or at crop harvest. Controlling weed seed dispersal has potential to manage herbicide-resistant giant ragweed by limiting replenishment of the weed seed bank. Nomenclature: Giant ragweed, Ambrosia trifida L. AMBTR; soybean, Glycine max (L.) Merr. Conforme las poblaciones de malezas resistentes a herbicidas se hacen incrementalmente más problemáticas en la producción de cultivos, estrategias alternativas de control de malezas se hacen cada vez más necesarias. Ambrosia trifida, una de las malezas agrícolas más competitivas en cultivos en hileras, ha evolucionado resistencia a múltiples sitios bioquímicos de acción de herbicidas dentro de la planta, lo que ha hecho necesario el desarrollo de métodos nuevos e integrados de control de malezas. Este estudio evaluó la cantidad y duración de la retención de semilla de A. trifida creciendo en campos de soja y márgenes de campos adyacentes. La retención de semilla de A. trifida fue monitoreada semanalmente durante las temporadas de cosecha desde 2012 a 2014 usando trampas de colección de semilla. Las