DELAYED SEEDING FOR WILD OAT CONTROL IN RAPESEED IN NORTHWEST ALBERTA
In a 4-yr study, rapeseed (Brassica campestris L.) was seeded where wild oats (Avena fatua L.) had been controlled either by various delayed seeding procedures or by an early spring application of trifluralin at 1.1 kg a.i./ha. The trifluralin treatment provided the best wild oat control. However, allowing wild oats to grow to the two-leaf stage, destroying them with cultivation and then seeding rapeseed resulted in commercially acceptable control (70% or more) with little or no loss of crop yield. Postponing cultivation until the wild oats reached the three- to four-leaf stage provided control that was almost equivalent to that attained with cultivation at the two-leaf stage but resulted in reduced crop yields. Destruction of wild oat seedlings at the two-leaf stage by paraquat or glyphosate did not improve the level of control over that provided by cultivation.Key words: Oat (wild), delayed seeding, rapeseed, trifluralin