From our perspective, the most immediate and noticeable distress comes from tiny invaders who pierce our tender new leaves and stems to feed on our sap. Aphids are soft-bodied insects that cluster on our undersides, causing leaves to curl, pucker, and become sticky with a waste product called honeydew. This honeydew then attracts sooty mold, which further blocks the sunlight we so desperately need for photosynthesis. Similarly, lace bugs target the undersides of our leaves, leaving them stippled with tiny yellow or white spots on the upper surface. This damage severely compromises our ability to create food, leaving us weak, discolored, and vulnerable.
Some pests do not just feed on our surface; they invade our very structure. The rhododendron borer is a particular menace. Its larvae tunnel into our stems and branches, disrupting the vital flow of water and nutrients. This internal damage causes wilting, dieback of entire branches, and can be fatal if the infestation girdles a main stem. Leafminers, on the other hand, operate on a smaller but widespread scale. Their larvae burrow inside our leaf tissues, creating pale, twisting trails or blotches called mines. While a few mines are a cosmetic nuisance, a heavy infestation can cause significant portions of our foliage to brown and drop prematurely, again reducing our photosynthetic capacity.
Fungal diseases attack us in various ways, often thriving in the very conditions we azaleas sometimes prefer—cool, moist, and shaded. Powdery mildew appears as a white, powdery coating on our leaves, buds, and young stems. It distorts new growth and causes leaves to yellow and fall off, weakening us over time. More dramatically, petal blight (Ovulinia azaleae) strikes our beautiful flowers. It begins as small, pale spots on our petals that rapidly expand into soft, brown, mushy patches. In wet conditions, a entire blossom can collapse and rot in a single day, cutting short our reproductive display and wasting the immense energy we invested in blooming.
Perhaps the most dangerous threat lies beneath the soil. Phytophthora root rot is a water mold that attacks our root system, especially in poorly drained soils. From our perspective, it is a silent killer; the first signs above ground—wilting, yellowing leaves, and stunted growth—only appear after the damage to our roots is severe and often irreversible. Our roots become dark, mushy, and unable to function. In contrast, leaf gall (Exobasidium vaccinii) is a conspicuous but often less fatal fungal issue. It causes our leaves or flowers to become thickened, distorted, and fleshy, turning pale green or white before eventually turning brown and falling off. It saps our energy but is rarely fatal if managed.
