These are truly the dog days of summer, and even the trees are trying to leave town one branch at a time. Scott has the heat caused you to flip your lid? What are you talking about now? I’m talking about a phenomenon called sudden branch drop (SBD).
According to Julian Dunster in the Tree Risk Assessment Manual Second Edition:
“Sudden branch drop – sudden, unanticipated failure of a tree branch with little or no discernible defect; often associated with long horizontal branches and warm temperatures.
(A variety of species)…are known to drop branches unexpectedly in calm conditions and high temperatures.
Because failure occurs without wind load, the material properties must change or cracks must propagate for the wood to fail. These changes are likely due to changes in hydration. Crack formation must be due to temperature changes and drying of wood.
At this time, it is not possible to predict failure or mitigate risk due to SBD.”
Sudden branch drop can be a cause of major heartburn for risk assessment qualified arborists. Often during these super hot, dog days of summer, primarily pecan and red oak trees will start dropping large branches. Unfortunately, there are generally not obvious defects that can help to identify branches likely for failure and help mitigate risk.
The problem has been exacerbated by canopy loss from the ice storm. The top side of branches are being exposed to brutal sunlight and heat, and it is likely causing sun scald. Sun scald is damage to branch tissue and usually found on the top side of branches. It increases the likelihood of branch failures. This is happening all over town.
In a recent visit with Don Gardner about sudden branch drop, proper watering was his best solution. Don’t forget that your mature trees need at least one good soaking watering per month (get the soil DAMP approximately 4 inches deep). Your trees need to be watered year round if we haven’t gotten at least 2 inches of rainfall in the month.
Be aware of the old adage “Take two aspirins not the entire bottle.” If you haven’t been watering your trees much this summer, begin with a short cycle watering in the morning and then water again in the evening. DON’T FLOOD THE AREA UNDER YOUR TREES. Give your trees a chance to gently absorb water. Too much water in brittle trees can exacerbate the problem. Don’t forget to water the area under the entire tree canopy.
That’s it friends. Sorry for the lengthy email, but this is a super important subject at this time of year and in these conditions.
