The Puttgarden had been looking bad all season (still). There were areas where grass seed would germinate and then die shortly after. Areas have been reseeded 6 times, but to no avail. The top 2 " of soil was replaced twice in some spots. There were areas on the ends where grass had not grown in 2 seasons.
We observed a few things:
It was the case that the flowers in the vicinity of the dead spots were not growing well. The impatiens by this time of year have been 2 feet tall in the past, but are barely 6" tall. After much pondering and in discussions with a local Golf Course Superintendent we now believe that the use of a pre-emergent herbicide and uneven application of it has caused areas that are contaminated.
It appeared that the top layer of soil was getting very slimy. Over watering? I'm not sure. The irrigation was cut back severely this year, but it was a very wet rainy season and the irrigation was not on much at all.
Spiking the green with the pull behind rotary spiker and then broadcasting dry topdressing which was washed in the holes by rain seems to have helped the soil from sliming over again and newly germinated seed seem to be taking. It has been slow to mature, but has survived.
Next year we will not apply pre-emergent herbicide.