From the picture posted I think it is dog urine. Brown patch has a grey like outter ring and the inside of the disease does not look staw color as your picture shows. Brown patch isn't a concern in bermuda either. Spring dead spot is a major disease for bermuda but that's not it, nor dollar spot. As far as when to fertilize, well if it's not above 90 and you can provide good water then for bermuda the time is now. A good fertilizer for bermuda is one with a high first number with 50% slow release. As far as the rest of the information on taking care of your lawn, try searching online. Bermuda is pretty fool proof and is good for people who don't want to fuss over their yard.

If this damage is recent, then let's assume its not because of pest invasion, they're long gone from our northern lawns and are deep underground now making babies that will come up next spring. I suggest you bring out the rake, the fan rake to begin with, and pull out all what grass is weak and wont stand up to winter anyway. If you feel there are bugs in the soil, treat with diazonon or other soil treatment. I suspect its not bugs. Much of other pests that invade our lawns have to be shown by a soil test. Many of the usual bugs only cause minimal damage that is regularly put up with and the affected lawn damage is then repaired. A normal fertilizing program can repair most winter damage by encouraging turf roots to advance through our lawns. Mowing to remove only 1/3 of the grass height and leaving the clippings on the lawn can help. Too much thatch, depriving the lawn of sunlight and proper moisture absorbtion, can do damage. Regular raking to remove thatch can prevent most of this damage. Improving sunlight to areas where shade is prevalent can help a lawn produce new grass. Where trees shade areas, prune the lower branches to admit more sunlight. Where rain is not sufficient to encourage development of grass, then we have to turn to watering the lawn at appropriate times and amounts.

The grass appears to be Kentucky Bluegrass(KBG). KBG will spread on its own via rhizomes if provided with the conditions it needs to thrive. From the pictures, it does not appear that it is necessary or desirable for you to seed. Overseeding KBG is often a futile endeavor, as it takes long to germinate (up to 3 weeks) and it has a hard time competing with the already established grass. Also, Poa A germinates about the same time as KBG (they are in the same family after all), and so it will be tough to control the Poa A since it will germinate right along with the bluegrass. Plan of action: - Do nothing but weed control via spot-spraying until mid-August. - Fertilize mid-August using a nitrogen rich fertilizer at a rate of 1 lb N/thousand sq ft. - Apply pre-emergent early September to stop the Poa Annua. You may need to re-apply late fall, read the bag instructions. - Apply 1 lb N/thousand sq ft mid-September and mid-October. - Apply 2 lbs urea/thousand sq ft mid-November as winterizer. - Mow the bluegrass as high as your mower will go until summer is done. - Drop your height of cut to 2.5"-3" in the fall to encourage spreading. - At the beginning of fall, pull plugs of grass from healthy areas and transplant them into the bare spots. They will spread and fill in. This should get your lawn in good shape by next spring. I hope dchall comes along with the watering mantra, you will need that as well. Uh, I just noticed you used the S word. What are we talking as far as direct sun, how many hours a day? KBG likes full sun.

Since you're not reporting something large and heavy sitting there, I'm going to bet on a fungal issue. As to what, precisely, that's impossible to say without much closer and more expert inspection. Poke around a bit. Do you see white or gray threads? (Wash your hands afterward and do not touch your grass or any other grasses until you do so). Does your neighbor water, or have a watering system that automatically waters the lawn, or is your weather quite wet at the moment? Or is that a naturally damp area for some reason? Engineering controls would include cutting down the water--fungi don't like being dry, and optimal watering for most lawns is once a week, deeply. Treatment, initially, if it is a fungus, would be any good off-the-shelf wide spectrum anti-fungal. It's now far too late to reseed in Michigan, although your neighbor can wait until February or March, spread seed then, and allow it to sprout by itself when the weather warms. It's not optimal, and the area will require care through the summer and probably a reseeding again in fall, but snow seedings are the second-best (and not very good) way to get a lawn area started.