Where do you live?

Were you mowing in Feb when you fertilized?

What is Stonewall (organic or synthetic)?

What kind of grass do you have? Have you ever overseeded?

Is the spot in question well drained? or does water sometimes pool up there?

How often do you water and for how long?

From your other message I know you are in NCarolina and have TTTF. You probably were not mowing in Feb and Stonewall is a Lesco synthetic. Since you were not mowing yet, that Feb app was wasted on the weeds. At that time you probably should have used a pure Pre-em type material.

Still wonder about drainage and watering habits.

Do you have a full soil test result set since the problem started? Those exact symptoms can be indicative of both overages and shortages of a couple of micronutrients.

I am outside Charlotte, NC - Zone 7 - TTTF lawn.
Stonewall is "Barricade" pre-emergent.
Did a full renovation last fall - Aerate/overseed.
Spots are well drained.

Have not irrigated this year at all. Just natural rainfall. About 2 inches in Feb and March. Did have a 15 day dryspell over the past few weeks, but rest of lawn is green and good.

Soil test from last Nov:
Ph = 6.1
Buffer Ph = 7.70
CEC = 9.9 meq/100 g
Acidity = 2.4 meq/100g
P = 196
K = 87
Ca = 2032
Mg = 525
Zn = 1.9
Mn = 51
B = 0.3
Cu = 1.6
Na = 39
Base Saturation:
Ca = 51%
Mg = 22%
K = 1%
Na = 1%
Total = 75%

A translation would be awesome...could it be a nutrient problem? How do I correct that?

Also, can I do a second app of pre-emergent now?

Can anyone help?

Prodiamine has up to a 8 month residual for "grassy weeds", depending on how many pounds per acre you applied.
Refer to your label.

>"can I do a second app of pre-emergent now?"

Why would you want to?

Are you trying to prevent broad leaf weeds now?

Not the best solution for everyone but when my lawn started dying for the third year running (quite costly to sort out) I replaced with artificial grass.

Here is a link that might be useful: Artificial Grass