More about over-fertilization
The individual plant cells in the root begin to dehydrate or “burn.”
If too much fertilizer is applied,
causing too much water to be drawn out of the grass plants, they
will dehydrate to the point where they cannot recover. This is very
likely what has happened to your lawn.
Uneven application of lawn fertilizer will
look like the striped lawn in the photo above
Long brown stripes in your lawn indicate
over-application of lawn fertilizer
to certain specific areas
To remedy the problem, clean up any visible piles of weed and feed
(wearing chemical-resistant gloves). Be sure to broadcast the
cleaned up weed and feed in another part of your lawn rather than
throwing it in the trash. Then try to leach the excess fertilizer
out of the soil by running a sprinkler on the area for two or three
hours a day for a week to ten days. Depending on the severity of the
misapplication, that may be sufficient to take care of the problem.
Try re-seeding the area and see how well the new grass plants grow.
If they grow for a while, then start to die out, there is still too
much fertilizer in the soil. You will have to remove the top two
inches of soil from the affected area and replace it with fresh
topsoil. Then re-seed the area with grass seed that matches the rest
of your lawn as closely as possible.