Is there any correlation between turf disease and certain elements in well water? I have a large lawn that is healthy. 2 weeks ago it got dry, so I watered a 4000 sq ft area that I wanted to keep green. That area stayed green and a few days later we got some rain (1"). So the whole yard is doing good except the areas that had been watered with well water. The entire 4000sq has Rust. Non of the other areas have any signs of disease or rust.