The drought we’re experiencing can cause significant bark injury to young trees with smooth bark if you don’t take immediate action and water them thoroughly. This is the time of year that trees have started to go dormant in preparation for winter. It is also their last opportunity to absorb the water they need to carry them through the winter.
Unless smooth-bark trees are able to store sufficient water in the fall, they are likely to suffer split-bark damage on the south and west side of the trunks during the winter months. The injury appears as long vertical cracks starting two to three feet from the ground extending upward several feet. If we have severe cold, the cracks can open, allowing disease-causing organisms to enter the sapwood and initiate rotting. Once rot starts, there is little you can do other than try to keep the tree healthy with proper fertilizing and watering.
Irrigating the ground beneath the tree can prevent the problem. Knowing where the roots are helps you maximize watering.
There are few roots capable of absorbing water near the trunk of a tree. As the top of the tree grows, so do the roots. The majority of the roots grow in the upper 10 inches of soil. As the branches spread, so do the roots. If you stand under a tree at the beginning of a rainstorm, you will notice that very little rain penetrates the canopy so you can remain relatively dry for a while. If you stand under the drip line of the branches, you will get wet.
In other words, the leaves of the branches tend to shed the rain outward. If you were to dig into the soil just beneath the drip line of the branches, you would find young tender roots, which means that the roots are extending outward as the branches extend outward.
Thus, to maximize the effectiveness of watering, spread a soaker hose three to four feet inside the drip line of the branches. The soaker hose should circle the entire drop line of the tree. To thoroughly drench the soil, leave the hose turned on for five to six hours. Due to capillary action, the soaker hose will saturate a band of soil approximately 18 inches wide. To thoroughly irrigate the tree, move the soaker hose toward the trunk of the tree about three feet and water another five or six hours.
Soaker hoses improve water efficiency by 80 percent because the water drips from the hose to the ground with little evaporation. Soaker hoses are made of recycled rubber and can be used year after year providing you store them under cover when not in use.