Changing colors may be due in part to stress
Leaves are starting to change, and it might be stress. We’ve been down this road before, you and me. We’re starting to see some color in the trees. The leaves are turning and it’s not just because fall is ahead of us. It’s a bit early for that. A lot of our trees are under stress.
There’s all sorts of things of things that can put trees under stress: disease, insects, improper planting, damage from the storms and even residual effects from the drought last summer. Because of the shortage of rainfall last year, some trees were not able to store up the water they needed before winter. In addition, droughty soil gets colder and freezes deeper, which can damage roots. The roots near the surface are the least hardy. Another hot and dry summer this year didn’t help matters any.
Trees on small spaces like boulevards or in parking lots don’t have enough ground around them to absorb the rain. Trees on hills can be affected because the water runs down the hill before it can be absorbed. It isn’t all stress. Some of it is normal.
How can you tell if the changing leaves are the result of stress? Look at where the changes are happening. If lots of trees are changing color, it’s normal. But if it’s happening in just one tree – or one part of a tree – it’s not. Stress is site-specific. If you see it in just one place, that’s stress, and stress on a tree isn’t good. Right now, a lack of water is one of the major stress factors. And small trees will require more water that large ones. Large trees can usually take care of themselves. One of the first signs is when a tree begins to shed it’s leaves. It’s trying to conserve water. On the other hand, the trees with a little color to them aren’t trying to forecast an early fall. The leaves turn color for a reason and colder weather isn’t one of those reasons. Frosty mornings are not a reason either. It’s more of a function of the length of daylight, anyway.
And even though the days are getting shorter, they haven’t really gotten that short. Meteorologists tell us that we are sort of careening from one extreme to the other. Be we seem to be moving into a period of longer, warmer autumns. They predicted a warmer-than-usual September and they were right. Summer isn’t quite over yet. That’s the good news. The bad news is that I’m hearing we are in for a longer and colder winter. Go figure.
Not all bright leaves are early. It’s normal for some foliage to have started changing color. Butternut trees will start turning as early as August. Sumac, which is actually a shrub should start turning any day now, if it isn’t already. And there’s a vine, the Virginia creeper, that’s also changing now – and is right on time. Some species, such as ash, are known to get a jump start on the fall color change. So it’s not uncommon for people to see one or two ash trees in their neighborhood that have colored leaves.
However, early coloration in other tree species can mean they are stressed, either from a disease or physiological stress, such as lack of water or too much of it. As a result, these trees will shut down operations for the year before other individuals of the same spe cies. For example, stressed maples are prone to early coloration and will change color up to a month earlier than their healthy counterparts. And we are seeing a lot of this happening right now. People who enjoy fall foliage should expect an early change in most of the state, in fact, fall color change has become noticeable in the northern part of Iowa now. If we can get some warm days and cool nights, we can expect this year’s fall color display to be quite brilliant. The extreme far northern and extreme far southern tier of counties received enough rainfall this year to “save” their autumn color display. As for the rest of us well, we’ll just have to wait and see.
Heavy migration underway
It’s hard not to notice that fall is here. I like to walk in the rain. I like the distant smell of burning leaves. And I like to stand outside my back door at night with a cup of coffee in my hand and listen to the geese flying overhead. This sound usually signals the coming of either spring or fall. Lately – in the past week or so – the night air and the sky above have been filled with the sound of geese passing overhead. They are moving south a bit early this fall and they are moving fast. And they’re not stopping. Most of the fall harvesting is yet to get underway so there’s no spilled grain (corn and soybeans) on the ground for them. Worse yet, there is no water to hold them. They ponds are bone-dry and the rivers are extremely low. I visited Big Wall, Little Wall, Briggs Woods and Beemer’s Pond and Seiser’s Pond the other morning. Only a few Canada geese were on Beemer’s Pond and I could only find three ducks (Gadwalls) on Little Wall Lake at Jewell. Where you find water, you find waterfowl and we just don’t have the water this fall. Time will tell.
And now have a good weekend.