Field Studies on Dynamic Pollen Production, Deposition, and Dispersion of Glyphosate-Resistant Horseweed (Conyza canadensis)

Rongjian Ye, Haiyan Huang, John Alexander, Wusheng Liu, Reginald J. Millwood, Junming Wang, C. Neal Stewart

Research output: Contribution to journalArticlepeer-review


Glyphosate-resistant (GR) horseweed has become an especially problematic weed in different crop production systems across the United States and the world. In this field study, we used a nondestructive measurement system to analyze the pollen production, deposition, and dispersion of a Tennessee glyphosate resistant (TNR) horseweed biotype in Knoxville, TN during the 2013 pollination season. We observed that the pollination season of TNR horseweed lasted about 2 mo (54 d). About 78.93% of horseweed pollen was released between 9:00 A.M. and 7:00 P.M. during each sampling day and the release peak was at about 1:30 P.M. The seasonal release of pollen grains was estimated to be 5.11 million grains plant-1. The release rate data indicated that the integrated horizontal flux density and deposition flux density contributed to 78.17% and 21.83% of the release rate, respectively. We also found that pollen concentration decreased with distance from the source field; the average pollen concentration decreased to 50.69% at a distance of 16 m from the source plot. This is the first result of a systematic, direct examination of the release rate (emission and deposition), release pattern (daily and seasonal), and dispersion pattern of GR horseweed pollen. Nomenclature: Glyphosate; horseweed, Conyza canadensis (L.) Cronq ERICA.

Original languageEnglish (US)
Pages (from-to)101-111
Number of pages11
JournalWeed Science
Issue number1
StatePublished - Jan 1 2016


  • Pollen release rate
  • pollen dispersion pattern
  • pollen release pattern

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science


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