Leaf Scorch of Trees
Leaf scorch is a physiological disease of plants which occurs when the roots are unable to obtain sufficient water to supply the top of the plant. Leaf scorch occurs when plants are transpiring rapidly during periods of high temperatures with hot, dry winds or during droughts. Any plant may experience this, but symptoms are more commonly seen on broadleaf trees such as maple, ash, elm, chestnut and poplar.
SYMPTOMS
Symptoms may begin with yellowing along the margins or between veins of leaves, or you may simply notice dead, brown patches in these areas. Seriously affected trees will have many leaves scorched and brown with only small amounts of green tissue on the leaves. The whole tree may develop symptoms, but frequently only the leaves on one side or a few branches turn brown. The tree will not die from leaf scorch unless it is seriously deficient from water.
In Utah, symptoms usually begin to show up in July and August. Newly transplanted trees may also develop leaf scorch because they have not had time to establish a good root system. Trees with damaged roots (from construction, etc.) or growing in areas surrounded by pavement also have difficulty in obtaining sufficient water and leaf scorch results. Often, similar leaf symptoms can be caused by excess salts in the soil which are taken into the plant and moved out into the leaves. Overfertilization and leaching of road salt applied during the winter can make soils high in salts.
CONTROL
The best control for leaf scorch is to prevent conditions which usually create scorch. Deep irrigation during periods of drought and/or high temperatures are essential, especially during windy periods. Keep trees vigorous with proper fertilization in spring or late fall, and prevent injury to the roots and trunks from construction, lawn mowers or girdling roots. Removal of a few branches by judicious pruning will reduce the water demands and consequently reduce leaf scorch. Treat with iron to alleviate any iron deficiency. See Utah Plant Disease Bulletin 45.
Sherman V. Thomson/Extension Plant Pathologist
Scott C. Ockey/Plant Disease Diagnostician
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