On a hot, still summer afternoon, a gum tree can drop a large, healthy-looking limb with no wind at all. Arborists call it summer branch drop or sudden limb drop, and it's part of why gums earned the "widowmaker" nickname. It's a different problem from wind damage, which our storm tree damage guide covers.
On a hot, still summer afternoon, a gum tree can drop a large, healthy-looking limb with no wind at all. Arborists call it summer branch drop or sudden limb drop, and it's part of why gums earned the "widowmaker" nickname. It's a different problem from wind damage, which our storm tree damage guide covers.
Key Takeaways
In a 1983 study, R.W. Harris described sound limbs breaking out of mature trees "during calm summer weather", usually during or after hot, calm afternoons. There's no storm, no warning crack and often no visible decay. One minute the branch is there; the next it's across the driveway.
Nobody has a single agreed answer. An ecologist quoted by the Adelaide Park Lands Association links it to weather, tree health, crown weight and branch junction strength, calling it a likely "resilience measure". Perth gardening expert Sabrina Hahn told ABC Radio Perth that heatwaves add stress because trees can't draw up enough water. Limbs already carrying fungus or damage are the likeliest to go.
Harris found breakage most commonly occurs 1 to 4 m from where the branch joins the tree, on long limbs extending to or beyond the canopy edge. So what does a risky limb look like from the ground?
The Adelaide ecologist names river red gums and sugar gums as the most susceptible.
Harris's advice was to shorten and lighten long horizontal branches, and it's still the best prevention. Our tree pruning crew does this selectively to AS 4373, without lopping. Book it before the December to February heat. Our gum tree guide lists other hazard signs, and our heat stress guide covers summer watering.
On hot, still afternoons, don't park or sit under big overhanging limbs.
If a limb has come down or one is hanging, keep everyone clear and call us on 0481 114 103. For a pre-summer check, get in touch with Lumberjacks WA for a free written quote once our team has seen the tree in person.
