Dollar spot would be my guess Roger, you don't have the conditions for pythium or brown patch right now. If it is dollar spot a cheap generic propiconazole is the best option, however this is best done preventively. Dollar spot won't kill tall fescue but it will take a little while for it to grow back. Make sure your turf is not under drought stress,this will increase the severity of dollar spot, and make sure to water early morning and not in the evening. Unless the dollar spot begins to spread rapidly, early morning with heavy dew you may see some mycelium, I would save my money for brown patch control at the end of may/early June. Also, Tenacity is a fine product but there are lots of other options for broadleaf weed control that won't give you any bleaching. 2,4D, Diacamba, and MCPP is a typical three way broadleaf herbicide that is very effective, of course it depends on what weeds you have.

Well just like you said I woke up this morning and saw a few spots in the yard with the white mycelium!! It was a damp misty night but the Mycelium was on top of green grass and not in the brown areas that I noticed getting in the car for work I didn't look too hard. Its scheduled to ran the next few days so I can't put anything down right away. Any suggesting on treatment in th e meantime? Also I noticed the brown areas seem to follow the lawn mower wheel tracks. I thought this also might indicate Pythium blight ?

Roger, the conditions just are not right for pythium, it's not nearly warm enough in your area. Also, mowers can move dollar spot around as well. If you were low in nitrogen fertility I would say give the lawn some nitrogen but you are good. Propiconazole is your best option for dollar spot control. Spray in the early morning when there is little chance of rain for the day.

Its so confusing most of these diseases look so similar. I think your probably right about the dollar spot but now I was reading about Leaf spot also looks shows similar symptoms. I took some better pictures tonight.

These are my tenacity white spots.
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If your talking about gray leaf spot the conditions wouldn't be right for disease development. Gray leaf spot would be more likely in July.

Not Grey leaf spot necessarily, but what they call Leaf spot / Melting out. I don't know honestly it seems like dollar spot is pretty common and the symptoms are there so I'm going with dollar spot on this one.

I receive my bottle of Honor Guard (propiconazole) but I have not applied yet. I've been researching but there are some questions I have still, such as the best time to apply, in the morning when its cooler or during the day? No instructions on this that I can find. Also not sure really if I should just spot treat or treat the whole lawn. The recommended rates are .5 oz / 1000 sq ft for dollar spot.

Any suggestions on the above questions?

The Conditions have been pretty warm and dry, yesterday I took a moisture reading from the dollar spot areas and they were toward the beginning of the "wet" (#8/10 on the soil master meter I have). This area is where the run off goes during heavy rain and gets shade half the day from the house so it looks like too much moisture is the issue here. Also this is the area i seeded later in the season so when you part the grass you can still see straw that is still only partially decomposed which is probably retaining moisture too. There are other small areas in the yard with symptoms but this area is the worst.

Hey Roger, leaf spot/melting out is more of a bluegrass disease, not to say tall fescue can not be infected but it's usually not a serious issue. That being said the pictures that you took, which were pretty good by the way, it's just hard to diagnose from a picture. However, I feel pretty confident that I see a couple of pretty typical dollar spot lesions and the conditions are right in your area.What your looking for is a tan lesion with a reddish/brownish margin. Spraying the propiconazole you want to spray early morning before 10 am and knock the dew off first either give the lawn a couple of turns with the irrigation heads or mow. Then spray at two ounces of product per gallon of water and one gallon of water should cover a thousand square feet. Use tracker due if you have it, so you don't have any skips in coverage. There should have been a label with the HonorGuard. You can find the label online if you search HonorGuard.

Here is a link that might be useful: Dollar spot lesions

UPDATE!!

So just to recap from last time I did end up putting down one application of Honor guard. The areas that were killed off from the dollar spot have not come back but the grass has spread out so much you can barely see the areas anymore. I think the outbreak had a lot to do with the week of humid weather and several days were my grass was wet going into the night.

Fast forward to today I have concern about one spot in particular that I don't think is dollar spot. I had this spot back in April too. Any ideas? I see quite a bit of fertilizer granules in the soil where this spot is so it could be a nitrogen hot spot.

Overall looking pretty good!
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Spot I need to identify
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Close up
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Looks good Roger. I would say you might have spilled some fertilizer in that spot, but that usually wipes out the entire spot and the edges are dark green and growing quickly. Another guess would be brown patch but in your close up I don't see any evidence of brown patch in the close up, and I don't know what your weather conditions were at the end of April.