The fall season can be an excellent time to plant trees. During the spring, soils are cold and may be so wet that low oxygen levels inhibit root growth. The warm and moist soils normally associated with fall encourage root growth. Fall root growth means the tree becomes established months before a spring-planted tree and is better able to withstand summer stresses. The best time to plant trees in the fall is early September to late October. This is early enough that roots can become established before the ground freezes. Unfortunately, certain trees do not produce significant root growth during the fall and are better planted in the spring. These include beech, birch, redbud, magnolia, tulip poplar, willow oak, scarlet oak, black oak, willows, and dogwood.
Fall-planted trees require some special care. Remember, that roots are actively growing even though the top is dormant. Make sure the soil stays moist but not soggy. This may require watering not only in the fall but also during the winter months if we experience warm spells that dry the soil. Mulch also is helpful because it minimizes moisture loss and slows the cooling of the soil so root growth continues as long as possible. (Ward Upham)
Leaf scorch is starting to show up on maples and other trees and shrubs. This is not a disease but rather a physiological problem associated with damaged roots, storm damage, limited soil area, or hot, dry winds. This year, the wet spring may have compromised root systems so that they are now struggling to provide the moisture needed by the leaves. Moisture is lost so quickly from the leaves that roots can't absorb and transfer water quickly enough to replace what is lost. Though scorch is usually associated with droughty periods, it can appear even when the soil is moist.
Scorched leaves turn brown or, in some cases, turn black from the edges and between the major veins. If severe, the leaf may drop. Leaves may be affected over the entire tree or may be affected only on one side. White pines are also prone to this condition due to the delicacy of the needles.
Though scorch can be due solely to the weather, the condition of the roots of plants can make them much more susceptible to this condition. Shallow soils such as those over hardpan or rock lead to a limited root system that may not be able to absorb all the water needed. As mentioned, trees may be more sensitive to scorch this year because of the heavy rains many areas received this spring. In certain cases so much rain was received that oxygen was driven from the soil resulting in root damage. That root damage is now making it more difficult for trees to provide all the water needed for the leaves. Also, root damage due to disease, insects, poor drainage or construction can cause poor water uptake.
To help alleviate damage due to dry soils or limited root systems, water once per week for recently transplanted trees or every two weeks for large trees if there is no rainfall. Mulching small trees or shrubs will help conserve moisture. (Ward Upham)
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Ward Upham is the Kansas State Master Gardener Coordinator and runs the Horticulture Response Center. Other contributors include K-State Extension Specialists.