The planting depth is critical, especially for trees on dwarf or semi-dwarf rootstocks. When planting, dig the hole deep enough to allow the tree to be planted with the graft union 2 to 3 inches above the ground. If the tree is planted too deep and the graft union is below the ground level, the scion variety will form roots and the tree will become a standard-sized tree. Also, if the graft union is buried, the tree may send up …
What are burr knots?
Burr knots are root initials that develop above ground. Rootstocks are selected for their ability to produce roots, but some rootstocks try to produce roots above the ground. The severity of burr knot development differs depending on the variety and region. In several rootstock trials, trees in Virginia tended to produce more burr knots than trees in most other locations. Sometimes several burr knots will coalesce and partially girdle the tree. Burr knots are considered undesirable because they can be …