Gardening Tips: February 12, 2013
Snow, Snow and More Snow!
Another blizzard has descended upon much of the Northeastern United States with perhaps a foot or more snow predicted locally and the prospects of a third storm coming this weekend. Most residents of the Catskill Mountain/Hudson Valley region are pretty experienced at dealing with winter but February is a trying month by itself and this weather only makes things seem worse.
Of course kids love getting unscheduled days off from school and people who make a living plowing snow are not complaining. Sales of shovels, deicing salt, snow tires and associated items are making these items scarce or even unavailable in some stores. At least most northerners do prepare for winter, but our neighbors to the south have really had a bad time.
Last week I drove through South Carolina and Georgia on my way to Florida and I was shocked to see so many cars and trucks off the roads, even on Interstate 95, perhaps the most heavily travelled north to south route in the US. My grandkids, who were born in Florida, have never actually seen a snowstorm in real life. Someday I would like to have them experience that sensation, even though their Grand Bob has lost most of his affection for snow, as well as for winter in general.
Our local wildlife fare pretty well for the most part during snowstorms but if the accumulation exceeds more than a couple of feet some animals are at risk while others will do very well. Deer generally den up under evergreens and can survive for a few weeks munching on the foliage but in extreme conditions starvation can occur. They are also subject to higher predation from coyotes although the number of deer killed by coyotes is really pretty insignificant compared to humans, cars and trucks.
Rabbit and mice populations can actually expand as the snow provides shelter from predators such as hawks and foxes. I hope that you put some sort of rodent protection around the base of fruit trees, especially apple trees. The bark and inner bark of woody plants is quite nutritious to these rodents and they will take advantage of the snow cover to girdle entire orchards in extreme cases.
Unfortunately there is little that can be done once a woody plant has been girdled. If the rodent only eats the outer bark, the shrub will often recover, but if the tissue just beneath the bark, the phloem, is removed, the shrub usually dies. Phloem tissue conducts carbohydrates (sugars) from the leaves to the roots and it forms only a very thin layer between the outer bark and the xylem tissue inside. Xylem tissue conducts water.
Depends on damage
Most of what we call “wood” is xylem. A tree trunk that is six inches in diameter is probably 5.9 inches of xylem. Xylem and phloem cells look like skinny straws and constitute the plumbing of all plants. Woody plants that have been girdled will often leaf out in the spring, as if they are unharmed because the preformed leaves only need water to expand and there is lots of xylem tissue to conduct the water. This is why it is possible to “force” twigs of spring flowering trees and shrubs to bloom by immersing the cut ends into water. Without phloem tissue however, the plant often dies shortly afterwards. No living thing can live on water alone.
There is a silver lining to this sad story however. Both the xylem and phloem tissue are produced by a very thin layer of cells that is located in between them. This tissue is called the vascular cambium because it produces vessels. The xylem vessels make the trunk get thicker each year as the tree grows but the phloem tissue gets crushed every year because it is stuck under the bark. If the hungry rodent does not completely eat the vascular cambium, while munching on the phloem, the cells may produce new phloem tissue. The rodent is after the carbohydrate rich phloem and rarely eats any xylem.
Make a plan
So if the snow should melt between now and March, wrap some hardware cloth around the trunk of your fruit trees at the base of the trees to protect them from girdling. As the winter progresses the chances that the trunk will be girdled increases drastically, because the furry little rodents are happily reproducing under the snow cover. When snow cover remains intact from November until May, all woody plants are at risk and not just fruit trees. I have a feeling this may be a tough winter for some of our landscape plants.