The Buzz

Tough Talk

As gardeners, we are used to dealing with the vagaries of natural forces. Changes in rainfall patterns, insect and disease pressure, fluctuating maximum and minimum temperatures, and a myriad of other unexpected phenomena of greater or lesser import that serve to remind us that the only constant in nature is change. Acceptance of such natural phenomena is not so difficult, given that we can do little to change them. We simply adapt to the current reality and make the necessary edits to our plant palettes or garden maintenance routines and hope for the best. Such forces are, to borrow a phrase from the French Structural Anthropologist Claude Levi-Strauss, “good to think with.” They allow us ample opportunities to ponder the mysteries of nature and our place in the larger scheme of things, opportunities that I, for one, relish tremendously, for the deeper insights that often come as a result.

I would like to argue that anthropogenic phenomena are also “good to think with,” and the phenomenon that comes immediately to mind is the recent discovery and frighteningly rapid spread of the Crapemyrtle Bark Scale. First sighted near Dallas, Texas in 2004, the scale has spread throughout the southeastern states, primarily along the major transit routes used by production nurseries, and has become firmly entrenched in the Memphis area. Once I saw the scale for myself last summer,  I began to ponder the possible vectors for the spread of the insect, trying to sort out how movement of the scale might be affected by examining common landscape practices. As many of us note with varying degrees of horror, each winter hundreds, if not thousands, of crapes are summarily beheaded, with the resulting branches piled onto trucks and trailers and carried on to the next job until the vehicle is full and the load needs to be disposed of. Not once have I seen a crew clean their tools between jobs, nor their clothes, both of which the insects easily adhere to. So the insect has found a prime vector for perpetuating itself across the Mid-south in the countless landscape crews that do this kind of work. Personal opinions of this practice aside, I think it’s time we reconsider whether or not such “pruning” is desirable. 

Now we get to the tough talk. Given that the most widely recommended treatment protocol  for this new insect pest involves the application of systemic insecticides, and that said insecticides, neonicotinoids, are currently being investigated for their role on Colony Collapse Disorder in honeybees, I think it’s time we take a good, hard look at our desires to keep these lovely but over-planted trees in our gardens. Just this season, I have talked with dozens of gardeners and homeowners about what to do with their affected crapes. My usual response is that I wouldn’t hesitate to perform a one-cut pruning operation.

Having followed the repercussions of large-scale chemical application over many years, I can’t help but feel that the use of systemic insecticides to (hopefully) control a pest of ornamental trees that offer little in the way of ecosystem services is a viable long-term strategy. Just considering the sheer number of crapemyrtles gracing the streets and gardens of the southeastern states and doing the math to estimate how much of these chemicals would be required for a single treatment for each tree gives me pause. Certainly, the companies that manufacture the insecticides and those that apply them are set to profit tremendously, but do we really want more chemicals like this in our environment?

Or can we find another, preferably native, tree to take the place of crapemyrtles. I can think of a few right offhand that suit my preferences-serviceberries, dogwoods, and fringe trees would be at the top of the list, followed by yellowwoods, hornbeams, redbuds and deciduous hollies. None of these have the long bloom period and colorful bark of the crapes, but they offer some combination of flowers, fruit, fall color, and/or interesting structure, in addition to significant ecosystem services. Of course, treatment or removal of your crapemyrtles is a personal choice, and I doubt any of us gardeners will judge you for your decision.

Having very recently discovered the scale in the garden, the MBG Horticulture staff is in the first phase of developing a strategy for the crapes here on the grounds. It is likely we will treat some that we feel are truly important features of the garden and remove others to make space for new plantings. As always, these challenges can be seen as opportunities and incentives to make changes in the garden, and are most definitely “good to think with.”

-Chris Cosby
Senior Manager of Gardens

Posted by chris cosby at 1:58 PM

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