When do wild oat seeds become viable?

Wild oat (Avena fatua) continues to be one of the most problematic weed species in western Canada due to high percentage of seed loss, dormancy, large populations, and high frequencies of herbicide resistant populations. However, wild oat are known to extend their seed heads above crops such as wheat, and moreso for shorter crops such as lentil. The first year of a two year study was conducted in Lacombe, AB and Saskatoon, SK in lentil and wheat to determine when wild oat seeds become able to grow the following year, based on weekly clipping and removal of the seed head. Clipping for each crop began when the majority of seed heads were visible above respective crop canopies. Preliminary results indicate that wild oat viability increases with time. However, while wild oat viability at the first of the clipping timings in lentil was near zero, by the first panicle clipping in wheat viability was between 12 and 37%. Weed management techniques that aim to target the seeds while forming must occur very quickly after wild oat seed head emergence above the crop canopy; later techniques will result in seeds that can grow simply being planted back to the soil.