Can someone tell me what this is.

[420benz]

This is Bermuda grass. I use Scots fertilizer in the spring and fall

 

[zigs]

Looks like drought to me, either that or there's some localised rubble under the lawn.

There's tarmac under this bit

 

[Plantdoctor]

Drought or scorch from over-use of fertiliser.

 

[LIcenter]

Looks like some type of fungal disease. As stated above in can be brought on by under watering (drought) or over fertilizing. Bermudagrass likes high nitrogen, so I doubt it's from over fertilizing. Here's a link to help you narrow it down some.
https://www.todayshomeowner.com/how-to-deal-with-grass-fungal-diseases-in-your-lawn/

 

[mgmine]

In the north I would say it was grubs. Not sure about your area. Have you contacted Scotts?

 

[420benz]

Most of the yellow areas are where i walk from the front to the back.Could that be the problem?

 

[Plantdoctor]

Presumably that strip near the building is in a rain shadow?

Still think it is basically lack of water.

 

[LIcenter]

Most of the yellow areas are where i walk from the front to the back.Could that be the problem?

Most people tend to walk the same line without even knowing it, so I would have to say no. Throw some water at it to see if it comes back. Still think it is fungal tho.

 

[420benz]

Thanks guys for the info.I just treated it with a fungiside.Hope it works