Yes, it sounds as though the tree has heat and moisture stress, which can be caused by disease, high temperatures, other bad environmental conditions, or injury.
To put it simply, the most likely cause of the problem is that your tree may not be getting enough water, even though you have been trying to keep it hydrated. The root systems of fruitless mulberry trees can grow so rapidly that what may have been enough water in previous times will not be enough water now. Particularly during a drought, the leaves will be giving off water faster than the roots can take it up.
A deep watering will get the water into the root system so that it will be able to take up enough water to counterbalance what the leaves give off. For best results, you can cut off the side of a plastic gallon jug and place the cut side touching the ground. Then stick the hose through the top where the lid screws on and let the water run for 10-15 minutes. Alternately, you can use a soaker hose placed around the drip line, dripping the water slowly every week throughout the balance of the summer and early fall.
There is a slight possibility that you may have the opposite trouble. If your soil does not drain well, the mulberry tree will not tolerate it when the soil remains soggy for more than a few days. If this is the case, you can amend heavy soils with compost or manure to improve drainage or you can have a drain installed.
Root damage can also be a cause of reduced moisture to the roots. The shallow roots of mulberry trees are easily damaged by machinery such as lawn mowers or trimmers nicking the tree bark repeatedly while in use. A traumatic event, such as an ice storm or lightening can also become the cause of tree damage.
Check the bark and leaves for signs of diseases such as bacterial leaf scorch, infestation from fungi, and root rot. These can also be the cause of the problem and they can severely the roots and the inner wood.
If the tree is only low on water, it should come around fine for next spring. However, if the tree seems to be diseased or severely damaged you can contact your local extension office. See below.
University of Nevada Cooperative Extension
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