I am seeing it again this year and still don't know the cause. Driving down the road with all the bermuda lawns around here you see a lot that have green squigly marks through out. Like you would see clippings waved through the yard after a heavy rain. It is only on synthetically treated yards. I treat with both synthetics and organics. My yard is 100% organic as is my parents and it does not have this effect. However, my neighbors yard, which I treat with synthetics, is getting this same effect. My wife thinks it is cool, it bugs me to no end and it is obviously not natural. Any thoughts? I know it has something to do with nutrient uptake but anyone know the true cause going on underneath?