Patches of dying grass
I have a problem where there are small areas of my lawn that are either dying or not growing back as quickly as others. (See posted picture showing close up of lawn. We mowed it about 2 weeks ago and you can already see the healthy growth towards the back of the picture while the foreground is showing grass that did not bounce back after the mowing).
I live in Berkeley, California. According to the GardenWeb, that's Zone 9.
This grass is a Mello Rye grass and was installed as sod last November (2013). We initially hand watered with a garden hose for about 2 weeks then we left the watering to our sub surface drip irrigation, watering 8 mins once a week until about 3 weeks ago where we increased the frequency to twice a week. (Prior to laying down the sod, we took away 6 inches of dirt and placed new earth because our backyard previously was under concrete).
The grass was beautiful up until about 2 to 4 weeks ago when this started. And now more and more patches are showing up throughout the lawn.
We fertilized once, back in March, with Scotts Turf Builder with Crabgrass preventer.
We have someone come by about once every 2 weeks and he usually takes about two thirds off the grass.
We're new gardeners so we don't have a lot of experience with lawn care. We haven't yet tried any remedies as we don't know what the problem is. Would appreciate any help in identifying what our problem is (too much water?, too little water? aeration? fungus?) and any solutions.
Thanks very much!!