The strange white tipped grass will have a powdery coating if the problem is powdery mildew. If that is not present, the most likely way that grass becomes white tipped like this is application of a pre-emergent weed killer. There are a number of those that will cause some weeds and some grasses to lose chlorophyll and turn white in this way. It may have been applied as a mixture in some grass seed that was being used to patch areas.

Courtesy of NYBG Plant Information Service