Louisa Master Gardeners

Problem Shrubs FAQs

  1. What shrubs should I avoid planting in my landscape?
  2. Problem Free Shrubs for Virginia Landscapes

1. What shrubs should I avoid planting in my landsacpe?

The shrubs listed below can be considered problem shrubs. These species or cultivars are often sent to the Plant Disease Clinic at Virginia Tech for diagnosis. Avoid using these shrubs in new landscapes if possible.

Buxus sempervirens ‘Suffruticosa’ (English boxwood) tends to suffer from root diseases, including Phythophthora root rot, English boxwood decline, and nematode feeding. Minimizing cultural and environmental stresses can help prevent these diseases, but control options are limited once symptoms develop. The species B. sempervirens (common box) is not prone to English boxwood decline and tends to have fewer root problems than Buxus sempervirens ‘Suffruticosa’. B. microphylla (littleleaf box) is also relatively problemfree. Hybrids of B. sempervirens and B. microphylla var. koreana are also available.

Ilex crenata (Japanese holly) often suffers from black root rot, a fungal disease, in the landscape. Typical symptoms include sectional dieback of the foliage and blackened roots. Control involves repeated fungicide treatments, which can keep the disease in check but do not rid the soil or roots of the fungus. Certain other hollies, including Ilex glabra (inkberry), Ilex x meserve(blue or Meserve holly) and Ilex opaca (American holly), are also susceptible to this disease, although no species is as chronically affected by it as Japanese holly.

Photinia x fraseri (redtip) is susceptible to the fungal disease Entomosporium leaf spot. Symptoms of this disease can be quite severe on plants that are sheared and/or fertilized frequently in the summer. These practices stimulate succulent growth, which is very susceptible to infection.

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