How to Manage Pests

Pests in Gardens and Landscapes


Fasciation affects many plants, including alyssum, aster, carnation, chrysanthemum, geranium, impatiens, Marguerite daisy, nasturtium, petunia, and primrose. Fasciation is an abnormal flattening of stems, often appearing as if several adjoining stems have fused. Fasciated plants have short, swollen clumps of distorted shoots. Leaves growing from distorted stems are abnormally abundant and undersized. Distortion often develops at the plant base, and crowns may appear galled. Sometimes only new terminal growth is affected. The cause of most fasciations is not understood. Some may be genetic and others may be caused by bacterial or viral infections. Fasciation bacteria survive on infected plants and debris. They spread in water and through wounds.


Control bacterial fasciation primarily through good sanitation and use of pathogen-free plants. Avoid injuring the base of plants, especially when plants are wet. Keep the base of plants dry. To control fasciation to all potential causes, do not propagate or graft symptomatic plants. Remove and dispose of infected plants, or prune and dispose of distorted tissue and do not propagate from those plants.

Stem and blossoms damaged by fasciation
Snapdragon stem and blossoms damaged by fasciation

Statewide IPM Program, Agriculture and Natural Resources, University of California
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