Here is a mystery problem from two of our sports turf students, Joel Rieker and Kevin Hansen. It is from a new Kentucky bluegrass grow-in on one of the new sand-based sports fields on campus. It is showing up as patches from one to two feet in diameter. Notice the close up of the turf in the third picture, showing a redish to purple discoloration on new growth.
I am suspecting a nutritional problem. My guess is phosphorus and I am recommending a application of phosphorus as soon as possible. I think that there is probably some fungal organism involved but I suspect that it is because the grass is deficient in phosphorus. We may also try some chlorothalonil fungicide on a test area. They will also do a soil test on the area and take a sample of the grass to the plant disease lab, but both will take some time. It is the end of the season and we do need to act fast.
I could be wrong and I would like some feedback on this. Has anyone seen this before on a bluegrass grow-in on sand? If so what did you do about it. Send the response to my e-mail, or put it on the comment section below. Any ideas would be helpful.