Whenever possible, we use soil or sometimes trunk injections to avoid foliar sprays. One of these products, Merit, is applied to the roots through a soil injection. This systemic insecticide has proved very effective on insects. It is also economical because one treatment usually lasts the entire season.
In fact, we have found that after two or three consecutive years of treatment, there is enough residual carried over that treatments are reduced to every other year.
Merit can take up to 60 days to be fully effective. Also, several waterings are needed after Merit is applied to initiate uptake. Because of this, we most often do Merit applications in early spring or fall. When necessary, we add other faster acting agents.