Choose dormant spray of lime sulfur for blackspot, powdery mildew, and rust. Or try a quick homemade spray made with baking soda. For the recipe, follow this link . Treat problems individually instead of using systemic combinations of insecticides or fungicides. Host Plants Different species damage rhododendron, azalea, and other ornamentals.
Some rhododendrons show resistance to root weevil damage.
For a list of these tough rhodys, follow this link . Control Hand-pick weevils at night when they begin chewing tender spring foliage. Get rid of the adults in spring before they begin laying eggs for the next generation. Teflon tape and sticky barriers help stop the weevils from climbing up the plant to feed. Do NOT apply chemical controls when bees are foraging blooms.