Hanging On By a Stem

As fall continues and winter approaches, it seems like some trees just want to stick to their summer foliage a little longer than others. Beautiful reds, oranges, and yellows are everywhere, but there are some trees that seem to have not taken notice or are just going brown.

Why haven’t all the leaves fallen yet?
As days get shorter and temperatures get colder, trees will release enzymes between the petiole and twig to form an abscission layer which aids in the separation of the leaf. If the temperature suddenly drops, it will kill the leaves still attached to the tree and fail to create the abscission layer. The retention of these dried, dead leaves is called marcescence. Marcescence can be caused by mild falls with sharp temperature drops or simply due to the species of the tree. Certain oaks, hazelnuts, lindens, and beech trees will naturally have marcescent leaves regardless of temperature changes.

When will marcescent leaves fall off?
Usually, winds will be the extra push marcescent leaves need to fall off the tree. They can also drop due to snow load or, at the latest, the push of new spring growth. The latter is very common in trees that always go through marcescence, such as the above-mentioned oaks.

Will leaves not falling damage my tree?
Marcescence by itself will not damage your trees. However, the extra weight and surface area creates a high risk of limb breakage during snowstorms. If you have any concerns about your trees, please feel free to reach out to our ISA certified arborists at Bailey Tree. As the premier experts for tree trimming in Denver, we always operate according to ISA standards to achieve the optimal health and well-being of every tree. Please contact us to request a free proposal to get your trees back on track.