Question
I live in the middle of Texas and my 15 year old sycamore tree now has yellow and brown leaves that are dropping off. We have not had a lot of rain this year and had a severe drought 2 years ago. How is the best way to water, how long and where on the root system, and for how long each time?

Answer
A mature tree can lose hundreds of gallons of water a day through its leaves, especially in hot or windy weather. If trees don抰 get enough water, they will experience stress when they can抰 replace the water lost through their leaves.  Signs of water stress are wilting, leaf scorch (browning of leaf edges), and even dieback of twigs and branches.  The older leaves of some types of trees, such as sycamore, turn yellow and brown and then drop from the tree in response to water stress... without the appearance of the wilting or leaf scorch.

The time of water is not important but the amount is. Water with 1 inch of water--place a pan under the tree and turn the sprinkler on and when the pan has 1 inch of water in it stop. Do this every third day for a month then once week unless it rains good. If your trees are growing in a lawn area, keep in mind that the grass may be using a large portion of water that抯 being applied through a sprinkler system.  Even if you think you抮e applying enough water, check the soil moisture in the tree root zone.  Make sure adequate moisture is reaching the soil and tree roots.  

Water should be applied in the 搑oot zone?  The fine feeder roots that absorb water are not located close to the trunk of established trees.  Most are situated in the area beyond the 揹rip line? that抯 the area beneath the furthest spread of the branches.  If the soil is shallow or compacted, the root zones may be wider and shallower than anticipated