They're Still Here

One of the advantages of living in the Midwest is the pronounced change that comes with each new season. Autumn in particular is anticipated largely because of the wonderful coloration of foliage. As the daylight lessens and the temperature get cooler our plants also adjust. Trees and shrubs transport material from the leaves for storage, and for the deciduous species the leaves are shed, although for some plants (especially oaks and beech) the leaves take some time, often months, to detach. This gradual and delayed dropping is called marcescence. Sometimes the temperature gets too cold in the fall too quickly, interrupting the normal process of senescence which leads to leaf drop, When this happens the leaves mostly remain attached to the stems and the color display is also sometimes affected (e.g., the Fothergilla pictured above). This abnormal behavior can led to tissue damage since the plant did not have adequate time to shutdown. However, the damage will likely not be noticed until the spring when dormancy is broken. The damage can be so severe as to kill the specimen, especially if a recently transplant and or if there is additional trauma during.winter. This sudden cold killing has occurred the past two years (2017 & 18), but it was especially noticeable in 2018. The temperature plummeted to a nighttime low in the upper teens for 5 days starting November 10th. I was doing yard work in this period and noticed that the conditions seemed particularly brutal and that many specimens of several species looked strange. Now almost two weeks later, leaves on many plants that would have naturally fallen are still attached--the abscission mechanism faulted. Not much we can do except wait and hope for the best. So, if you notice some dead or heavily damaged woody plants next spring, winter may not be the culprit.