Notched Edges on Rhododendron
Notches on rhododendron leaves that appear overnight may be caused by adult black vine weevils (Otiorhynchyus sulcatus). Weevil larvae emerge from eggs and enter the soil to feed on roots. In late May/June, they pupate into adults. The adult weevils feed on leaves at night, producing notches until only the petiole remains. New leaves and shoots are commonly attacked.
To control, plant resistant cultivars or treat with a chemical control when you first notice the notches. Contact Cooperative Extension for current control recommendations.