Salty well water and/or city water sprayed on foliage can cause burn. It can cause even more serious long term problems in the soil. Most all of the organic soil amendments help neutralize short term and long term sat problems. Injecting liquids such as compost tea, Garrett Juice and/or liquid humate into the irrigation lines is very beneficial and will eliminate even the cosmetic burn on the foliage. To get more than a broad shotgun fix, send a soil and water sample to Texas Plant and Soil Lab in Edinburg, Texas. They can offer specific solutions to solve the problem. Gypsum may well be one of their recommendations. And the most important step - stop using synthetic fertilizers. They are basically salts.