By AARON SAWATSKY-KINGSLEY
Remember last summer’s drought? It seemed interminable and brutal.
This summer it’s much different. Our current precipitation level for the year, as recorded by the National Oceanic and Atmospheric Administration, is 21.4 inches — just slightly above average. Last year, we didn’t reach that mark until mid-October.
In other words, we’re doing pretty well for rain this year. But even so, young trees need to be watered. In fact, they especially need to be watered right now. And this is especially because of what they experienced last year.
During Last year’s drought trees were put through plenty of stress. Even ones which were getting some water were probably drought stressed to a degree.
Drought stress was often expressed in wilting leaves, browning leaves or some leaves dropping entirely from the tree. In extreme cases all the leaves browned and fell to the ground. This is a tree’s first response to drought: since water is lost through leaves, a tree can conserve precious water in its branches, trunk and roots by limiting its leaves.
There is a trade-off for this, however. By decreasing leaves, the tree is also decreasing its ability to manufacture energy (through photosynthesis). This energy is necessary for the tree to carry out its life processes. Not only that, but some of this energy needs to be stored away — in the roots — for the following year, for the growing of new buds, leaves and flowers in the spring before there are any leaves to create new energy.
So, when a tree has to stop energy production in order to conserve water this can have a ripple effect, diminishing the tree’s abilities in the current growing season and in the following growing season.
This case is underscored for a young tree, which has smaller energy stores to begin with, and a smaller over-all leaf surface.
Young trees — resilient as they are — that were drought stressed a year ago used much of their stored energy to survive into this year. As a result, even though we’ve done quite well for rain this year, in the past three drier weeks I’ve seen a lot of young trees showing drought stress. Simply put, they are still recovering from last year’s ordeal. This means that now — late July and August — is the time to baby any young trees you can. Water them three times a week with a slow trickle of water for up to one hour.
Large trees were stressed last year as well, of course.
Healthy large trees have been able to absorb most of this drought stress. Their extensive root systems were able to seek out enough moisture in the ground so that leaves were not limited in any significant way, therefore, energy production wasn’t interrupted.
But large trees that may haven’t been quite so healthy are feeling the effects this year.
I’ve been out to see close to three dozen trees in the past two months, which a year ago seemed to be in good shape. This year, they are dropping leaves, showing branch die-back, or maybe never even leafed out in the spring.
Drought may not have been the ultimate cause for the demise of these trees, but it very likely was the straw that broke the camel’s back. In that light, it wouldn’t hurt to water your large tree from time to time, with a sprinkler that can distribute water over a wide area of the tree’s root-spread.
We are lucky to be having such a good rain year on the heels of a severe drought year. By doing additional watering now, we can really take full advantage of good precipitation to help our trees recover and establish themselves. This will translate to healthy, vigorous trees for years into the future., which we will be very happy for the next time drought comes our way.
Aaron Sawatsky-Kingsley is Goshen’s city forester