Sunday, November 6, 2011

AROUND THE GARDEN


For those of you who like “before and after” pictures, here are two of my Franklinia tree before and after the recent unseasonable snowstorm.

On the left is a flower dripping a little in the rain. On the right is the beautiful maroon foliage that remains – but nary a flower. This little tree, just barely taller than I am, has suffered many setbacks in its young life. Some winters it’s so frost-damaged that I cut it down and start over. This storm only damaged the flowers – possibly the tree is so flexible that it simply bent under the snow.

The Franklinia is a small tree discovered on the banks of the Altamaha River in Georgia by John and William Bartram, plant collectors who lived in Pennsylvania in the 1700’s. Named for Benjamin Franklin, a friend of John Bartram’s, the tree has never been found growing in the wild elsewhere, and vanished even from Georgia sometime between 1780 and 1803. All the trees sold today come from seed collected by these two botanists; William Bartram’s famous book, Travels, contains a spectacular color illustration of the tree.

Another survivor in my garden is the Dawn redwood, a relative of the Coast redwoods of California. Once thought to be extinct, and known only from the fossil record, the tree was found growing in the mountains of China in the 1940’s. Seed collected from those trees was propagated at the Arnold Arboretum, and this fast-growing conifer is a great specimen tree for the large garden. Unlike its West Coast relatives, the Dawn redwood is deciduous, and drops its needles shortly after they turn an astonishing peach color – the reason for the “dawn” in its name.

And that’s all the good news I can muster. These are hard times for tree huggers, especially here in Connecticut. And it isn’t just wind and snow: international trade has escalated the arrival of numerous alien pests, some so lethal that literally millions of trees have had to be cut to stop their spread.

Pathologists at the CT Agricultural Experiment Station in New Haven report that trees in particular are stressed by weather extremes, especially when one extreme follows close upon another. A very warm spell in January, followed immediately by plummeting temperatures, can kill buds and destroy both flowers and fruits. Worse, the trees’ energy is sapped by dealing with these erratic swings.

Now, here in Middletown, two unusually destructive storms have struck in just two months. A tree variety I have been promoting for several years, the Princeton elm, failed badly under last week’s heavy snow. Princeton elms had been widely considered one of the best shade trees available, proving resistant to the infamous Dutch elm disease. Alas, I have seen a dozen Princeton elms destroyed by this storm.

Some of the most beautiful ornamentals, the Okame flowering cherries, suffered the same damage – whole leaders sheared off under the combined weight of foliage and snow.

A contributing factor for much tree damage was the unusual amount of rain our area has gotten in the last two months. Trees can take up a great deal of water during their growing season, and this year, the trees have been very slow to enter dormancy. My sugar maples are usually totally bare by mid-October: this year, those leaves that weren’t blown off by Irene have hung on. The excess water contributed to the unusual weight that branches had to deal with.

Trees with dense canopies, such as beeches; trees with tight-crotched branches, such as elms or cherries; trees with large or heavy leaves, such as magnolias and redbuds – all were candidates for devastation. Shockingly, even famously strong trees like oaks were badly damaged as well.

Irene was painful, but at least it was predictable: hurricanes happen, even in this part of the world. The recent wet snow, however, is an example of nature run amok. Deciduous trees drop their leaves for many reasons; leaf drop clearly has an evolutionary benefit for trees that grow in our climate.

But what happens when the seasons get mixed up? A deciduous tree can’t suddenly rearrange its foliage strategy. Gardeners now face another quandary when selecting plants: not only do we need trees that can withstand winter temperatures of five to ten degrees below zero and prolonged summer heat above 90 degrees, now we must select trees strong enough to hold their leafy branches through heavy, wet snow. (If you shoveled your walk, you know how heavy that stuff was!)

Already, growers are being advised to avoid ash trees because of the Emerald ash borer, maples, birches, and poplars because of Asian long-horned beetles, dogwoods because of Anthracnose, oaks because of Sudden Oak Death, pines because of pine bark beetles – what will be left? Please tell me it isn’t the ironically named Tree of Heaven, also known as Ailanthus.

Perhaps some other trees from the fossil record will turn up – I’ll be waiting.

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