Agreed it is a moss, we battle it down here in many clubs throughout South America. High rates of iron sulfate will knock it back but not kill it. There is a chemical, which is a herbicide made in Brazil that works excellent and kills it completly after three applications over a three to four week period. This moss forms under anerobic conditions. Your much better attacking the problem, not the symptoms, something is causing the surface to remain saturated. Many times its the result of topdressing with a finer sand than what was used for the base of the green. Kind of forms a mini perched water table. The area where we had the biggest problem was a course along the beach. We had dews every day and cloud cover until one or two in the afternoon. Ideal for maintaining the surfaces wet. You have to get water off the surface, spiking helps, raising the height of cut helps, aerifying helps, wetting agent help as does the iron sulfate applications up to two pounds per 1000 square feet. Becareful with the iron sulfate, depnds what your PH is, better to be used at this concentrations only in high ph situations and gradually build up to these high rates. Greens will turn black for a couple of days from tissue burn but recover quickly. The active ingredient of the product out of Brazil, that really works is Carfentrazone Ethly and the product is called Affinity. Porgram is, 250 cc / ha. the first application, the second application after fourteen days another 250cc/ha and then 2 weeks later follow up with a third application of 125cc. I battled this problem with limited results for over fifteen years and now have completly eliminated the problem through this program for the past three years at several courses throughout South America.