The reason behind the Summer Limb Drop

The reason behind the Summer Limb Drop

By Lidia Boque Gousgouni
08 Feb 2018
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With the recent spate of hot summer weather, the number of tree limbs laying on the ground is striking – we see them on roadsides, in parks and on farms and often they cause damage on the way down. When tree limbs drop it’s not just the odd branch here or there, but many limbs, with numerous individual trees dropping just a single bough. This tends to occur in the late afternoon or early evening in summer or early autumn - often after several consecutive days of very hot, dry weather and no significant wind. 

So why does this occur?

Research confirms that trees do have a tendency to shed limbs without warning in periods of very dry weather. This is a phenomenon known as ‘Summer Limb Drop’. 

Summer Limb Drop can occur in healthy trees with no apparent defects. This makes it almost impossible to predict. Branches can break some distance out from where the branch joins the trunk, and they tend to ‘shear’ rather than ‘tear’ away from the tree. Summer Limb Drop affects many different tree species around the world.

Research suggests that Summer Limb Drop is caused by the drying-out of wood cells inside the branch. The wood becomes brittle, and can then break under its own weight. Much like snapping a dead stick, as opposed to a live stick that will bend and flex without breaking.  

So what can be done to manage Summer Limb Drop?

· Maintain tree health and vigour, including mulching the ground within the dripline of the tree.

· Ensure the tree is well watered in hot, dry weather.

· Restrict activity in the area around the tree at times of high risk.

· Ensure large, mature trees are regularly inspected and maintained by a qualified arborist.

It’s important to understand about Summer Limb Drop so you can take necessary precautions particularly after a few days of very hot weather.


Diary

If you’ve been thinking about studying horticulture – Wodonga TAFE has Certificate III in Horticulture timetabled to begin at the end of February 2018.  This course runs on Mondays, Tuesdays and Wednesdays but you can choose to study part-time if that suits.  Why not call into Wodonga TAFE’s horticulture department in University Drive, Wodonga and pick up a timetable for 2018 or you can see the details and apply online at;

https://www.wodongatafe.edu.au/courses/AHC30716/Certificate-III-in-Horticulture

Cover photo

You may have seen large limbs lying on the ground, this is probably from Summer Limb Drop.

Written by

Rod Hall, Arboriculture Teacher at Wodonga TAFE.