How to Treat Quaking Aspens for Borers
- 1). Water the quaking aspen trees with a watering can to make the soil at the base of the trees evenly moist. Keep the trees watered as necessary to maintain evenly moist soil.
- 2). Add a 4- to 6-inch-thick layer of cedar mulch around the base of the quaking aspens. This will help the soil at the base of the tree retain moisture and remain healthy.
- 3). Apply insecticide to the trunk of the tree or to the soil around the tree based on your specific insecticide. Treat between June and September since this is the period of time when boring insects lay their eggs.
Source...