John from Hendersonville, Nc writes
Control of rhododendron stem borer is difficult because the adults move around freely, often laying eggs under plants on which they have not chewed. By the time root damage is noticed, it is too late to save the plant. Cutting off and burning infested stems as soon as they are noticed in the growing season is recommended for control. Dormant oil spray like Hi Yield Dormant Oil Spray can be applied to kill overwintering nymphs prior to new plant growth. Summer oil, like Fertilome Liquid Carbaryl can be used in mid-June or early July for the crawlers.
Answer last updated on: 09/17/2013
