Do I Need Dormant Oil?
During late winter into early spring, shrubs and trees are just about ready to wake from their “dormant” state. They are about to start producing new leaves and flowers and fruits for the season. The trees aren’t actually sleeping of course, roots are active through winter but this marks the start of the growing season.
This early stage in the yearly cycle is a critical time for preventing many pest problems (and some diseases). A variety of bugs are still overwintering as eggs or are recently hatched and susceptible to dormant oil treatment before they cause bigger problems as adults.
The following three main pests and the plants that host them are receptive to dormant oil treatments. Do you have these plants in your landscape?
Scales: flowering fruit trees, magnolia, hemlock, arborvitae, holly, juniper, euonymus, lilac, oak, pachysandra, yew, maple
Mites: arborvitae, crabapple, elm, hemlock, holly, juniper, maple, ash, pine, spruce
Adelgids: hemlock, pine