Why does your Rhododendron hunnewellianum have white cottony spots? Diagnose the cause and fix it with our step-by-step guide.
These small, soft-bodied insects secrete a white, waxy, cottony substance to protect themselves as they suck sap from the Rhododendron's stems and leaf undersides. High humidity often favors their development in woody shrubs.
Aphid colonies produce a white, web-like secretion that covers clusters of new growth on Rhododendron stems. This often results in distorted or stunted leaves due to nutrient depletion.
Scale insects produce a white, filamentous coating that mimics cotton. In Rhododendrons, this can cause leaves to yellow and drop if the infestation becomes heavy.
While typically appearing as a dusty coating rather than 'cottony spots,' certain fungal stages can look like tufts of white fuzz on Rhododendron leaves during humid periods.
Your plant might also be experiencing one of these issues:
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