Influence of tillage, vertical seed distribution, and pyroxasulfone application timing and rate on control of wild oat (Avena fatua L.)

Abstract

Tillage and new herbicide options may be necessary for the control of herbicide-resistant wild oat. The efficacy of soil-applied herbicides such as pyroxasulfone can be influenced by edaphic factors and weed seed recruitment depth, which varies with tillage system. We investigated the effect of tillage and pyroxasulfone rate when applied in the fall and spring on wild oat biomass at three locations in Alberta in 2014–2015. The vertical position of wild oat seeds, with and without tillage, was examined at each site. Wild oat biomass was greater in untilled plots compared with plots with fall tillage at all locations. In two out of three locations, pyroxasulfone efficacy was superior when applied in the fall compared with spring, possibly influenced by low spring rainfall. A single tillage pass at the Edmonton and Kinsella locations did not affect wild oat seed distribution, but there was an increase in seeds present in the surface layer in the untilled treatment at Lacombe. Tillage, used in combination with soil-applied herbicides, may be an option to achieve acceptable control of herbicide-resistant wild oat.

Aries Guineagrass (Megathyrsus maximus Jacq cv. Aries) pasture establishment without chemical control in an environmentally protected area

“…Because of the importance of this weed, suitable methods of soil preparation and sowing may be an alternative to favor Aries Guineagrass development under unfavorable climatic conditions in environmentally protected areas that do not allow the use of chemical control for weeds. In this way, the conventional method, by promoting a larger number of weed seeds at greater depths (Mangin et al, 2018), may contribute to the establishment of Aries Guineagrass by reducing competition with weeds. From the 0.10 m depth, some weed seeds can germinate, however, they can become chlorotic, and consequently more susceptible to any method of management (Orzari et al, 2013).…”