Question
Las Vegas lawn - grass has several brown patches. Watering is
not a problem (and I'm not over watering). I have used a
fungicide for several weeks. No NEW grass will grow there.  Have
aerated as well.  Must I wait for fall or spring for reseeding?
Also, crabgrass has taken a good hold since the previous owners
took little care of the lawn.  I've brought the lawn back a lot
since we moved in in FEB 2004 but it still needs help.

Answer
Hi Art. If you have used fungicide it isn't brown patch, apparently.It could be army worms or cinch bugs, or grubs.
Since the crabgrass is doing well, it is obvious you have poor soil.
Fertilizing does not make rich soil, it feeds the vegetation.
It also feeds the crabgrass.
Comcentrate on making rich soil, and weeds won't grow in it.
Weeds like poor soil, and when you enrich the soil, they can't thrive in it.
You don't need all those fertilizers, weed killers and insecticides.
Go organic and your lawn will attract toads, lizards and grass snakes that will eat all the bad bugs that come on your lawn.If you have Asthma or allergies, they will get better too.Smelling all those chemicals can really mess those up.
Every spring and fall I put sugar on my lawn, at the rate of 1 pound per 250 to 300 sq.ft. then i water it in to a depth of at least 6 inches.
When I first started this, my lawn was full of dandelions, crabgrass, johnson grass, clover, chickweed and some I can't identify.
After the first time I used sugar, in a couple of weeks, and two mowings, about half those weeds were gone. In a few more weeks you couldn't see even one.
I did that again in the fall, and in the next spring. Weeds came up, but a lot less than the year before, and after a couple of years, they just don't even come up.
My next door neighbor didn't mow, water or anything, and his yard was a weed farm.It seeded mine, and I battled with it for years.After I started with the sugar, his yard was still full of weeds, and seeded all over the neighborhood, but they didn't come up in my yard.
I was advised to use dry molasses, but if you couldn't get it, sugar work work as well.I couldn't get dry sugar here then, so I used sugar.When I could get dry sugar, I tried it, but it didn't work any better than the sugar did, and the sugar costs about the same, and comes in smaller bags. Also I can pick it up when I shop for groceries, and don't have to make a trip to the nursery, and be tempted to buy a bunch more plants.
Dry molasses and sugar don't kill weeds, they make the soil rich.
Fertilizers kill beneficial insects that are needed to keep soil rich, sugar and dry molasses keeps them alive.
Watering often is not any better than watering too seldom. If you don't water to a depth of at least 6 inches.Deep watering encourages to grow deep. Shallow watering makes the roots come to the surface to get water. Shallow root systens are more suseptible to heat and cold damage.
It is summer, and if those roots are close to the surface, that may be why the grass is brown, the roots are dead.Probably scalded by heat.
Dig down and see how deep the root system is.
If the people who lived there didn't take care of or know about lawn care, chances are they watered a little every few days.
I water with a soaker hose, and when it starts to run off, turn it off and let it soak in, then turn it on again, until it is soaked down far enough.
I used to use Funginex for fungus, now I use baking soda disolved in water. It works better for me than the Fungicide did. I top in the spring dress with compost I make, in compost bins I make. They are way too expensive to buy.I don't mind paying $20.00 for a good steak, but I am too cheap to pay that much for compost bins.Besides, the ones I make, and the way I make my compost doesn't require turning.
Look closely at your lawn.If you see some brownish little worms in it, they are army worms, dig under a little and see if there are grubs under there. I used to have a lot of grubs, but my lizards eat them. Now I don't average seeing one a year.
I know that sounds like a lot of bull, and you should have heard my husband hoot when I told him what I was doing. But he sees the results, and he don't hoot no mo.
If those roots are dead, you are going to have to sod in those places.
Those are the only reasons I can think of for brown patches.
Wish I could help you more.
If you feel there is something I can help you with, please feel free to write anytime.
Charlotte