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1 November 2007 An Emergence Model for Wild Oat (Avena fatua)
Krishona Martinson, Beverly Durgan, FRANK FORCELLA, Jochum Wiersma, Kurt Spokas, David Archer
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Wild oat is an economically important annual weed throughout small grain producing regions of the United States and Canada. Timely and more accurate control of wild oat may be developed if there is a better understanding of its emergence patterns. The objectives of this research were to evaluate the emergence pattern of wild oat and determine if emergence could be predicted using soil growing degree days (GDD) and/or hydrothermal time (HTT). Research plots were established at Crookston, MN, and Fargo, ND, in 2002 and 2003. On a weekly basis, naturally emerging seedlings were counted and removed from six 0.37-m2 permanent quadrats randomly distributed in a wild oat–infested area. This process was repeated until no additional emergence was observed. Wild oat emergence began between May 1 and May 15 at both locations and in both years and continued for 4 to 6 wk. Base soil temperature and soil water potential associated with wild oat emergence were determined to be 1 C and −0.6 MPa, respectively. Seedling emergence was correlated with GDD and HTT but not calendar days (P = 0.15). A Weibull function was fitted to cumulative wild oat emergence and GDD and HTT. The models for GDD (n = 22, r2 = 0.93, root mean square error [RMSE] = 10.7) and HTT (n = 22, r2 = 0.92, RMSE = 11.2) closely fit observed emergence patterns. The latter model is the first to use HTT to predict wild oat emergence under field conditions. Both models can aid in the future study of wild oat emergence and assist growers and agricultural professionals with planning timely and more accurate wild oat control.

Nomenclature: Wild oat, Avena fatua L. AVEFA

Krishona Martinson, Beverly Durgan, FRANK FORCELLA, Jochum Wiersma, Kurt Spokas, and David Archer "An Emergence Model for Wild Oat (Avena fatua)," Weed Science 55(6), 584-591, (1 November 2007).
Received: 22 March 2007; Accepted: 1 June 2007; Published: 1 November 2007
Hydrothermal time
soil growing degree days
soil moisture
soil temperature
Weibull function
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