Why Are My Apple Tree Branches Splitting?

Apple branches that split — either partially, with a long crack running along the branch length, or completely, with a major branch tearing away from the trunk — represent structural damage that can permanently affect the tree's framework and create large entry wounds for disease. The causes range from a one-off mechanical event (an unusually heavy crop load, ice, or wind) to ongoing structural weaknesses or diseases that have been developing for years. Responding correctly depends on how severe the damage is and what caused it.

Crop load causing structural failure

In a very heavy fruiting year, the weight of hundreds of apples on a single branch can exceed the branch's structural capacity, particularly if the branch is growing at a wide angle from the trunk (more than 60 degrees) or has a co-dominant double stem with a narrow, bark-included crotch. In the middle of summer, a heavily laden branch may split at the crotch or along the main branch. Immediate action: support the split branch from below with a forked stake or tie it back to the trunk with a broad rubber strap. Reduce the fruit load on the damaged branch immediately to remove the weight. Clean the split edges with a sharp knife and apply wound sealant.

Narrow crotch angles

Branches that grow at a narrow angle to the trunk — less than 30–40 degrees — form a weak, compressed joint with bark included between the two stems. These narrow-angle crotches are inherently structurally weak and susceptible to splitting as the branch grows heavier with age. When a young tree is being trained, train branches with wider angles (45–60 degrees) using spreaders or ties; remove any co-dominant stems with included bark before they develop into major branches.

Canker girdling the branch

A canker lesion that has expanded to girdle most of a branch's circumference kills the wood and bark, leaving the branch structurally weakened — a point of likely failure in high wind or under load. Remove any branch that is more than 50% girdled by canker rather than trying to save it; the risk of sudden, uncontrolled failure is significant.