What has happened here? Is it a disease, a fertilizer spill, different soil type, or perhaps a different type of grass?

This is on a golf course at an elevation of about 1,200 meters above sea level in Hawaii. We can also find this grass thriving at Dalat in Vietnam at 1,500 meters and at Kodaikanal in India at 2,000 meters.

Can you identify the type of grass? This species of grass is classified as a warm-season (C₄) grass although it has intermediate characteristics between cool- and warm-season grasses, performing best at moderate temperatures. Click the image below to view at a large size.

I'll post the answer in a few days . . . and here it is:

This is white clover (Trifolium repens) growing in a stand of kikuyugrass (Pennisetum clandestinum) on the island of Hawaii. Clover is a legume that can fix nitrogen in the soil, and legumes mixed with grass can provide about 36% of the grass's nitrogen*. So we see the kikuyugrass has turned green where it is mixed with clover, and it has grown thicker, and taller, and faster, in fact so much so that it has been scalped, as we see in the background. This is an indication that the grass would respond with more growth if more fertilizer nitrogen were applied. Thanks to Nadeem Zreikat in Australia and Andrew McDaniel in Japan for solving this mystery.

*Heichel, G.H. and K.I. Henjum. 1991. Dinitrogen fixation, nitrogen transfer, and productivity of forage legume-grass communities. Crop Science:31(202-208)