Hello, I hope someone out there can help me with a problem I have had for years. In the fall most of my customer's lawns develop patches of light green almost yellow. I am pretty sure it has to do with fertilizer (iron maybe) but I can't see what I'm doing wrong. Usually I apply a 24-2-11 blend but this fall I tried a 16-2-11 blend with the same outcome. It only seems to happen in the fall. One person told me it has to do with soil temp. As the fall turns to winter the discoloration goes away. Oh by the way I deal with St. Augustine grass and I'm located in Central Florida.Has this ever happened to anyone else out there?