Nobody who lives in our area needs to be reminded that this has been a brutal winter. However, you may need a reminder about what this weather is doing to your valuable trees and shrubs. It’s drying out the leaves, needles or even trunk and stem tissue (i.e. desiccating them). Even our dormant deciduous plants may be subject to desiccation according to a consumer horticulture bulletin from Purdue University.
We’ve had a lot of snow, but we’ve also had a lot of wind, and it’s the wind that causes desiccation. Woody plants, especially evergreens, continue to function through the winter, giving off water through transpiration. This is part of the photosynthesis process. With the little bit of sun we’ve had, you wouldn’t think plants would be able to photosynthesize, but they do.
During transpiration, water is given off through the leaves or needles. The wind then blows the droplets away, and there is no way the roots can absorb more water through the frozen soil. Broadleaf evergreens’ leaves may turn brown at the edges or they may turn red or purple and curl. Needled evergreens will have tan spots where the needles were just too dry to sustain themselves.
According to the Purdue bulletin, severely desiccated deciduous trees will have dead twigs and buds. Some twigs will leaf out but die in the summer, especially if it’s a dry summer.
If you had anti-desiccant applied in the fall, you may need a second application. If you didn’t take this cost effective measure to protect your trees and shrubs, call for an application now. As soon as the snow melts sufficiently that we have access to the plants, we’ll begin scheduling anti-desiccant applications.
If you aren’t familiar with this product, it’s a clear, wax like material that coats the plant. Sunlight can get through it for photosynthesis. However, when the leaves transpire, the anti-desiccant prevents the wind from blowing the droplets of water away. Instead, they’re reabsorbed into the leaf and keep it from drying out.