Hi Andrew Finch! Congratulations on your new house! I would probably treat the whole lawn with herbicide, then pull out the dead crabgrass and put in fresh grass. It will be time consuming but it will probably be worth it in the end because you want to make sure that the crabgrass doesn't come back. I'm not an expert when it comes to lawn care though, but this is just my two cents. I hope this helps!

Have a nice weekend,

damask_rose_5 : )

It looks like a small area and can be easily pulled by hand and then get on a pre-emergent schedule. My bermuda-lawn(2800 sq ft) was easily 80% crab-grass 2 years back, spent that Fall-Winter (10 min/day) pulling 3 bags of crab-grass over a span of 2-3 months and then got on a pre-emergent schedule, it is now much better.(No crab-grass but dealing with other weeds now but that's ok :))

What type of grass is this?

Crabgrass doe not look like that. St Augustine grass does look like that and can be mistaken for crabgrass. It sort of looks like St Augustine mowed way too low and possibly ravaged by disease from overwatering.

Are those recent pictures? Can you move your camera into the shade and take a picture from no more than 6 inches away from the grass? Garden pictures always look better on cloudy days or in the shade. If you have any grass with yellow or brown spots, take a pic of that, too (6 inches).

I'm going to assume that is St Augustine. Stop mowing it for the next 3 weeks at least. Reset your mower to the highest setting. At that mowing height St Augustine will kill off all the other grassy plants like bermuda and most other grasses.

What is your watering schedule? How often and for how long are you watering? Do you have a sprinkler system or hose and sprinklers? Could that area of dead looking grass be a low spot in the yard that holds water when it rains? If it is, then you need to bring in soil or sand to fill that low spot to get proper drainage away from the house and pool.

This is going to be a beautiful lawn once you understand how to care for it. It is the only type of grass that will thrive under that palm tree.

Are you willing to use organic fertilizers? Have you used any fertilizer this year?

Oh, and what part of AZ are you in (mountains or desert)? I promise you we are not coming to steal your toilet paper. With the palm tree I'm guessing desert.

Wait, he has toilet paper?

Exact address, please.