Herbicide should have had no effect on greening this year.

What was your watering schedule last year (and this year for that matter)? How often and how deep did you water?

When were the last two times you fertilized and what did you use? Proper fall fertilizing is what greens up the grass early in the spring.

If you have grassy weeds the 2,4-d Weed-b-Gon will do nothing. 2,4-d is specific to broadleaf plants like dandelions, clover, dichondra, dollarweed, horse herb, etc.

It has been a weird spring. I think it will affect the use of preemergent herbicide back in March more than anything. It is hard to deal with a spouse who is less patient than you are. Even after it greens up they will remember. There is really nothing you can do at this point to make it green up NOW. Until you have active roots nothing will help. You will know you have active roots when the grass is up and growing.

The 2,4D harms Bermuda more than most people think--I only use it at half strength & it still stresses the bermuda out more than I like. If the ground temp is high enough, you should have activity by now, can you get a close up of the blades & stolons?

If you take more pictures, please wait for a cloudy day or make some shade to take the pictures. There is too much contrast in full sun. Get up to 3 inches away for a close up.

Last year we had a very bad drought late summer. We don't have irrigation so the watering was limited. I didn't apply any fertilizer in the fall as i was afraid to stress the grass out more than needed.

I'm sure all of this doesn't help and adds up to what is going on currently. Just don't know what anyone would do if they come out right now, that's what i am trying to avoid.

They would probably start by installing some irrigation... What kind of sprinklers have you been using?

Here are some pictures of the current state.

Last year I used gear sprinklers and it was a pain. Thinking of using oscillators this summer to give better coverage.

When should I apply the first fertilizer and any recommendations?

It's starting to come in, but you need to get rid of all that Brown gunk. We should be able to see dirt between the blades in those pics. That stuff shades the ground, delaying green up, then causes the stolons to root shallow into that layer instead of dirt. It's a vicious cycle, which is we always recommend scalping Bermuda at least once a year in the spring.

Should I try to get that stuff up with a rake or similar?

Sure, rake is good. Try not to use a power dethatcher, it takes forever to recover. If you have a huge yard, an aerator works well for this task also.

Here is an update...

I purchased a pull behind dethatcher and got about 20 mower bags of dead grass out of 13k sqft. I've had a big rain event last week of about 3" and it's been in the 80s. Half the back yard not on the slope is greening up but the other area is not. My thought is that the slope area has poor water retention and that's part of it. Going to do a shampoo treatment today as it's going to rain soon. When should I apply fertilizer and should I use a straight nitrogen?

attached pics for reference

thanks again for the help

Just follow the dosage on the bottle for the fish fertilizer? Does it matter if it's going to rain later today?

That area gets a ton of sun and heat as it faces south. Should be prime conditions for Bermuda.

Yes, just follow the label. Rain is fine, it won't hurt anything if it gets washed away & a little extra dilution won't be a problem either. You can spray it once every few days with that stuff to really kick start growth, it barely counts as fertilizer as it's mostly a stimulant for the plants

Should I hit it with some milo soon as well? Maybe wait a week or so?

Im just worried about the slope portion not having much growth yet...

Fertilize after the lawn has been mowed for the second time. Waiting ensures you have active roots to take up the fertilizer.

Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.

How do I make sure that's the case if some of the grass isn't fully green yet?

You can go out and shout at it or tell it embarrassing stories to try and encourage it to wake up. Or you could go back to 6 months ago and water it deeply and infrequently while it was still growing. At this point all you can do is duck and cover when your wife goes nuclear. Patience is hard to muster when you are the go-between for family matter.