University of Maryland Extension

Fungal Leaf Spots - Shrubs

leaf spots on mountain laurel

Key Points

  • Leaf spots caused by fungi often can be distinguished by their fruiting structures and pattern of lesion development.
  • There are numerous leaf spotting diseases that occur on shrubs, but few are lethal.
  • Most established shrubs produce more leaves than they need for normal growth. Unless severe leaf defoliation takes place, enough leaves are usually left for healthy growth.
  • On young shrubs or newly planted shrubs leaf loss is more detrimental.
  • When a shrub loses most of its leaves its food reserves are depleted which may cause dieback, decline, and/or death.
  • The majority of leaf spotting diseases are favored by cool, wet, spring weather.
  • Shrubs that are prone to leaf spotting diseases include aucuba, mountain laurel, photinia, roses (cercospora and black spot), junipers, firethorn, leucothoe, and rhododendron.

leaf spot leucothoe
A leaf spot disease on Leucothoe

Management strategies

  • In most cases, leaf spotting diseases will not threaten the health of the shrub.
  • The best management practices for most leaf spotting diseases involve pruning and removal of infected leaves and dead twigs during the winter or dry summer months.
  • Mature shrubs can be thinned for better air circulation.
  • Rake and remove infected fallen leaves in the fall and plant resistant varieties when available.
  • For plants such as roses, where leaf spots can be detrimental, select resistant cultivars and apply fungicides when necessary.

Rev. 2020

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