Once established, they require very little care other than removal of old and weak canes. The height and spread of most viburnums can be regulated with selective pruning in early spring. Some evergreen kinds can be sheared. Viburnums, which grow in shaded areas, are often attacked by powdery mildew. The European cranberry bush and the snowball viburnums are most susceptible to aphids.
Aphids are small insects that cause twisting and curling of the stems and leaves.
Other potential pests are thrips, spider mites, scale and root weevils. Nematodes can be a problem too. Nematodes are microscopic worms, which live in the soil and feed on the plant roots. Most viburnum are not seriously troubled by diseases or pests. The genus Viburnum is immense, and choosing the right selection for your garden is not easy.