Invincibelle Wee White Hydrangea has no serious insect or disease issues. In highly alkaline soils the leaves may develop chlorosis, but the plant is adaptable to a wide range of soil pH and texture. In periods of drought, the leaves may drop if the shrub is not given supplemental watering.
Occasionally, the shrub may develop bud blight, wilt, leaf spot, rust, or powdery mildew. These issues are usually minor and often resolve within a year. If foliar diseases are problematic, you can prune the affected stems. Make sure you dispose of cuttings away from the plant to avoid reinfection.
Aphids, mites, and scale are also known to attack the plant. While these pests are not of major concern, heavy infestations can reduce plant vigor. Aphids and mites can be treated with an insecticidal soap that kills the insects on contact. Scale insects should be managed using a dormant oil that will suffocate the juvenile insects when they are active.