Most rhododendron don't bloom until mid May. Now is the time to fertilize so that sounds OK.

Leaves with crescent shaped holes are the handy work of the Cranberry Rootworm, Rhadopterus picipes. It chews holes in the leaf, some of which are crescent shaped. Cranberry Rootworm, Rhadopterus picipes, are shiny and black with a greenish sheen, these beetles are about 3/16 inch long. They feed at night and hide in litter or under containers during the day. Beetles damage leaves by chewing oval-shaped holes. They are usually associated with container nursery stock in areas with dense shade. Remove ground litter and weeds from the area and reduce shade where possible. Treat late in the day and repeat once or twice weekly.

There are two types of bud on rhododendrons now, the foliage buds and the flower buds. Flower buds are usually bigger and beginning to swell in April.

Should I try to kill these rootworms? What do you mean by ground litter? mulch and weeds? And when you say treat late in the day, do you mean with fertilizer? My rhodo fertilizer says to apply every 3 weeks. Ok, the buds are pretty big and fat but do come to a point at the top. They are right in the middle of the leaves.

Thanks for your help with this!!

The cranberry rootworms live in the dead leaves and mulch under the plant. They climb the plants in the evening to feed and then return before morning. The object is to spray them at night when they are feeding. If that doesn't work, you will have to attack them where they live in the dead leaves and mulch. Personally I ignore them since they are not a big problem for me. They seem to just like certain varieties and leave the others alone.