Fasciation

Fasciation is a plant morphological abnormality in which the apical meristem becomes broadened and the resulting growth is flattened, producing broad, fan-shaped, crested, or ribbon-like stems and inflorescences. The affected growth can be distorted, with multiple shoots or flowers developing from a single point. Fasciation can occur in any part of the plant that contains meristematic tissue.

Causes include bacterial infection (Rhodococcus fascians) that releases cytokinins and induces tissue proliferation; viral or fungal infections; genetic mutations; hormonal imbalances; and environmental or stress factors such as physical damage, herbicide exposure (notably synthetic auxins like 2,4-D), nutrient deficiencies, or extreme temperatures. In some cases fasciation appears without a clear or identifiable cause.

Fasciation is observed across a wide range of plant groups, including crops, ornamentals, and cacti. Common horticultural examples include beans, lettuce, roses, gladioli, delphiniums, and cacti. External symptoms can be mistaken for other disorders, and diagnosis often requires assessment for signs of infection in tissue, sometimes supplemented by laboratory tests to distinguish infectious from noninfectious causes.

Management generally focuses on preventing spread and avoiding propagation from fasciated tissue, as there is no universal cure to reverse fasciation once tissue has formed. Infected plants may be removed to limit spread if a bacterial source is suspected. Some fasciated forms are valued ornamentally and can be propagated vegetatively, though they may continue to exhibit abnormal growth. The term fasciation describes a growth pattern rather than a single disease.