Micro-encapsulated (MEC) sprayable pheromone formulations have shown some promise as a tool for the mating disruption of the oblique-banded leafroller, Choristoneura rosaceana (Lepidoptera: Tortricidae), a significant pest of apples in North America. However, the effectiveness of these formulations is limited by an initial burst of pheromone followed by lower release rates through the season, and poor retention of microcapsules on leaves. We attempted to improve the efficacy of this technique by combining a MEC leafroller pheromone with a light grade horticultural oil. We hypothesized that the oil would stabilize the release rate of pheromone from the microcapsules, and increase the rainfastness of microcapsules on leaves. Small plots of apple trees were sprayed with either water, MEC pheromone, or a MEC pheromone and oil combination. The effect of each treatment was assessed using behavioural assays both in the field and in a laboratory wind tunnel. Our approach to controlling this pest has the broader goal of developing a viable alternative to the traditional application of organophosphate insecticides against tortricid moths in apple agroecosystems.