Abstract

URBAN, JAMES. 1989. Graft rejection affects tree survival. Landscape Contractor 30(7):26–29.

In any series of grafts, some will fail to bond, or the scion will die shortly after grafting. In most species of trees, the majority of graft unions are successful, producing strong, serviceable trees. Some additional graft failure may, however, occur during the first one to three years. In a few species, the unions experience some delayed graft failure, even after the plant has reached its final location on the landscape. Nursery professionals realize that red maple grafts are highly unreliable regardless of rootstock, with as high as a 20% failure rate occurring in plants 3-6 inches in caliper or greater. Unless the tree falls over, its decline or death can easily be misdiagnosed. A debate continues in the nursery industry as to which other species are susceptible to significant delayed graft rejection. Delayed root graft rejection can also stress the tree so that it is susceptible to a host of secondary disease or insect infestations. The best procedure is to expand your specifications to include requirements for identifying rootstock. By recognizing the level of care required to avoid purchasing such plants, we can reduce the number of defective trees planted in our projects.

• © 1990, International Society of Arboriculture. All rights reserved.