You also get the wisdom of the ages and people who might not have the same experiences. The advice I gave is based on years (and years) of reading and moderating forums for amateurs and professionals. Applying fertilizer on Memorial Day might be too late in your area due to the onset of summer heat, but as a starting point, it is a very easy date to remember. Whether you get disease or not depends also on grass variety, air circulation, dew, humidity, soil type, and other factors. I'm not sure why Georgia would be much different from other places where the taller grasses are the healthier ones. At the same time that the wisdom of the ages sounds like a good idea, you also get the senility of the aged. Tupersan is relatively new to my repertoire of garden products. I became 100% organic before I heard of it and seem to have a block about that product. In general I don't put any faith in preemergent herbicides but people I respect tell me they work. I do recall from my relatively recent reading that Tupersan works as tiemco says. Professional grass growers (livestock producers) fertilize with 1/4 of their annual nitrogen in the spring, and they always apply it after the initial flush of green growth has ended. They apply 3/4 of the annual nitrogen in the fall. They do it this way to minimize their mowing workload and to spread the productive growth along throughout the entire growing season. The wisdom of the ages here at GardenWeb also agrees with tiemco that combination fertilizer/weed killer products are not going to do what you expect them to do and it is better to use different products for the different requirements. Yes Mother Nature has Her own ideas about watering, but for what you do, you do not have to encourage weeds. Far too many people set their sprinkler to operate for 10 minutes every day. That schedule is going to germinate every seed in the garden. You have control over your own watering. Allowing the soil surface to dry out as much as you can will develop deep, drought resistant roots as well as minimize weed seed germination.

There is a reason. No, grass will not grow througn 3 inches of anything. What makes you think additional soil is the answer? Pictures. Cultivars planted.

It wouldn't make much sense to apply an organic fertilizer that late, since organic fertilizers need microbial activity for the nutrients to become available to the plants. Organic fertilizers can contaminate water, too. P is the biggest problem re: water contamination, but N can be a problem, too, especially in areas with sandy soil.

No, you need to use a quick release granular that is absorbed by the roots. The blades at that point in the year are basically dormant.