INTEGRATED WEED MANAGEMENT STRATEGIES FOR DELAYING HERBICIDE RESISTANCE IN WILD OATS

Herbicide-resistant biotypes of wild oats (Avena fatua) infest most ma jor cereal producing regions in the western United States and Canada. This paper reviews potential integrated weed management strategies tha t can be used to prevent or delay selection of herbicide-resistant wi Id oats plants. An integrated wild oats management strategy to delay o r prevent the development of herbicide resistance should be based on p reventing the movement of wild oats seed into the soil. Two ways to ac hieve this are by preventing the immigration of seed into the field fr om external sources, and by reducing or eliminating seed production by wild oats already in the field. It is becoming increasingly clear tha t reliance on continuous herbicide use as the sole means of weed contr ol will fail to eliminate wild oats and other weed seed from the soil seedbank. On the contrary, evidence is mounting that this practice wil l select for biotypes that are resistant to the herbicides used, espec ially where herbicides of the same mode of action are used continuousl y. It is essential, therefore, that herbicides be considered as just o ne component of an overall integrated system together with cultural co ntrol and other management strategies, and that agronomic principles b e considered when developing this system.