Ask Mr. Smarty Plants

Lagerstroemia indica, crape myrtle, is not native to North America. The Lady Bird Johnson Wildflower Center is dedicated to the growth, protection and propagation of plants native not only to North America but to the area in which they are being grown. However, the effects of salt water would be the same on a native plant, so we will try to make some suggestions to help. 

Probably you need a Time Machine, in order to go back to right before that water was dumped on the plants, and then not do it. Salt water is sometimes used to kill weeds but, like many herbicides, it will kill the roots. Once the roots of a plant die, there is nothing to sustain the tree. If you act fast and have some luck, you might be able to resuscitate them. First, don't fertilize them. This is always a knee-jerk reaction when anything goes wrong with a plant. The last thing your trees need right now is stimulation to put on new growth when it is gasping for life. Next, trim off about 1/3 of the upper part of the plant, treating it like transplant shock. Then, make sure the trees are kept well-watered, in hopes that will dilute the effect of the salt.

If this doesn't work, please consider replacing the trees with some trees native to the area of Hidalgo County, in far south Texas. You can go to our Recommended Species section, click on South Texas on the map, and search for native trees suitable for your purposes. But don't plant them until late Fall, or you will risk losing the new trees to the heat and drought of the Texas Summer.