Friday, November 7, 2008

Landscape and Nursery - Graft Incompatibility

Graft incompatibility can lead to plant failures in the nursery and landscape. The following is a short article on the subject.

Graft incompatibility

Graft incompatibility is due to the failure of the bud or graft union between a scion and an understock. For unknown reasons, the tissues of the two plant parts do not form a stable union. Failure of the union disrupts translocation in both the xylem and phloem and influences plant performance with age. Signs of graft incompatibility may be visible as an uncharacteristic intensity of the fall color. Disruption of translocation leads to a buildup of sugars during leaf senescence that intensifies fall foliage color. This is especially the case on Acer rubrum cultivars with known incompatibility problems. Graft incompatibility issues on these Acer rubrum cultivars led to production on their own roots in nurseries. Graft incompatibility remains a concern in fruit tree production.

Incompatibility is not easily detected and can surface at various times in a plant's life. Unfortunately, for many it surfaces when the trees are mature and affected by wind or some other environmental condition. Graft incompatibility can result in semimature trees snapping off at the base in wind storms. Failure of the tissue union is visible at the trunk/root collar. On plant species with known problems, check on the budding or grafting practices during production. Another form of incompatibility occurs when there are differences in growth rates between the scion and the understock. These differences can lead to disproportional growth at the junction of the two tissues.

Information and photo from a section of "Abiotic Plant Disorders - Symptoms, Signs and Solutions A Diagnostic Guide to Problem Solving" by Robert E. Schutzki and Bert Cregg, Departments of Horticulture and Forestry, Michigan State University Michigan State University. Go to for the full factsheet with photos.

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