Hydrangea paniculata · Shrub
Hydrangea scale: Prune out heavily infested branches or treat with horticultural oil during dormancy.
Powdery mildew: Improve air circulation and spray with a fungicide or bicarbonate solution if severe.
Aphids: Blast off with water, encourage natural predators, or use insecticidal soap.
Vine weevil: Apply systemic insecticide granules to the soil in spring and autumn.
Leaf spot: Remove affected leaves and avoid wetting foliage when watering.