"When all you have is a hammer, everything looks like a nail." I think that came out wrong. I was not hinting at anything you said. I was setting up for what I was about to say. My hammer is corn meal, which in the organic world is recognized as a fungal disease preventer and cure. The nail is your yellow grass. When I see the yellow grass, I assume it is a fungal problem. I can see where that could easily be misinterpreted. Sorry. YES, you have to wait until late summer to reseed. Why? Well you don't have to but if you want good results, wait. Seeding now will give you a yard full of crabgrass right away and later on, any grass that did germinate will die from the heat allowing the crabgrass to fully take over. If you want to fix that for the future, you could seed in some Kentucky bluegrass in the late summer. It will spread to fill in weak spots where fescues do not spread.

WOW, to the guy that mentioned pythium blight. I think this is exactly what it is. I went to Google Images, and it looks really similar. It also sort of occurs in the same area every year which as OP mentioned, it's probably a fungus. AND, I think I know what's triggering it. Its my June Summerguard fertlization. I think the high nitrogen is causing it. Because my neighbors lawn is perfect and she does not fertilize in the summer. Read below. WOW if this is what it is, I am so grateful to you guys. INFO: Cultural practices can be used to promote an environment where infection by Pythium species is limited. Irrigation is an important cultural practice to monitor. Watering early in the day will allow grass blades to dry and thus decrease the probability of leaves remaining wet overnight. Irrigation also has an impact on the relative humidity within the foliar canopy of turfgrasses. This is the major reason that late afternoon and evening watering should be avoided on warm days. Providing for good surface and subsurface drainage when establishing new turfgrass sites, and renovating areas where water can pool in established turfgrass areas is another important step in Pythium blight management. Removing thatch can improve drainage, reduce drought and nutrient stress on turf and remove sources of Pythium inoculum. Thatch should be removed if it is greater than 0.6-1.2 cm (0.25-0.5 in.) in depth, depending on height of cut. Thatch is removed by vertical mowing and topdressing with sand or soil. A balanced system of turfgrass nutrition is also a key to controlling Pythium blight. Excessive fertility during hot months, particularly nitrogen, can exacerbate disease pressure. Levels of nitrogen applied to turf should be monitored, and monthly applications of less than 25 kg of nitrogen per ha (0.5 pounds of nitrogen per 1,000 square feet) during periods of hot weather are recommended. When applying nitrogen-based fertilizers use slow-release sources or "spoon-feed" turf with light foliar applications of fertilizer during spring or summer when occurrence of Pythium blight is most likely. Avoid calcium deficiency and maintain a slightly acidic soil pH. Promote good air flow across golf greens and other areas of turf by pruning trees and shrubs to promote light penetration and increase air movement to dry. When mowing, avoid areas of wet turf when the temperature is > 21ðC (70ðF), as this will help minimize the spread of the pathogen. Wash mowing equipment before entering unaffected areas. Also, alleviate soil compaction, in order to improve turfgrass root growth. When overseeding with cool-season turfgrass species, delay the process until late summer or early fall when the nighttime temperatures have cooled to

Yes, the turf has been physically wet almost every day for the last three months. In some areas I can see the soil black and glossy.

There are people who say "spray fungicide" at any possible sign of fungus and there are people like me who refuse to use it. Nitrogen exacerbates fungal problems, so it's generally good to hold off on fertilizer if you suspect fungus. However you may have had nitrogen deficiency and needed some. Thank goodness you didn't use the urea! Milorganite for the most part is slow release. Try keep the grass blades dry, so if you need to water, do it early in the day so the grass can dry off before evening. If the problem looks like it's spreading and you are worried about major damage, here is some information on the kinds of fungicide least damaging to the mycorrhizae fungi: fungicides and mycorrhizae You had a soil test last year. Did it say you were low in potassium? If you were, Milorganite doesn't provide any. You could use potassium sulfate 0-0-50 to supplement the Milorganite. If the soil test did not indicate a deficiency, don't worry about it. Some general info on mycorrhizae: Mycorrhizae: so what the heck are they?