Is there any possibility that someone spilled some chemicals in those areas? My guess is 'no' because you say you are able to grow grass every now and then. Could it be places where someone piles up yard trash every now and then? In my opinion your only solution is to use some organic materials that you have not already tried. Either you have bugs in that soil or you have a recurring fungal disease. Bugs don't usually cause immediate decline, so I'm voting for fungus. How big an area are we talking about? The organic solution to fungal disease is to use ordinary corn meal, like the stuff you cook with. The application rate to kill existing fungus is only 20 pounds per 1,000 square feet, or 1 pound per 100 square feet. If you only have small areas, then you can easily get the corn meal at the grocery store. If you want to treat your entire yard, and I would strongly suggest that, then find a feed store (call around) that carries it in 50-pound bags. I paid $6.75 this year for a bag. HOWEVER, corn meal only works if you have the proper soil microbes. After the use of the fungicides you mentioned, I am going to say you need to replenish your soil microbes with compost. This is going to be much more expensive. You can either buy it in bags and move it yourself, or order it from a local supplier and have it delivered. In my neighborhood excellent compost costs $40 per cubic yard and the delivery charge is $35-$40. One cubic yard will dust over 1,000 square feet. That is a light dusting and that is all you need. Smothering is the biggest mistake made with compost, so you don't need any more than 1/4 inch. After you apply the compost, use a push broom to sweep it off your grass blades and lift your grass blades up. Otherwise they will die. Some people can use a rake on compost but with the stoloniferous grasses in the south, the push broom works much better. If you are going to try this, the compost and corn meal can go down the same day. You can even mix the two together. But if you have any residual fungicide already on the soil, corn meal won't work. If you have used any fungicides this calendar year, then just apply the compost and hope for the best. You have to wait a good 3-4 months after using fungicide to get the full effect from the corn meal. There is a second kind of corn meal on the market that is causing more and more confusion. The one you want is ORDINARY whole ground corn. Even cracked corn will work. The other one is called corn GLUTEN meal. It has different properties and is used for different purposes. You want the inexpensive one. The reason ordinary corn meal works is that as it decomposes on the soil surface, a fungus grows on it. That fungus is immediately attacked by another fungus called Trichoderma (try ko DER ma). The Trichoderma fungus feeds off of other fungi. Once the Trichoderma population grows on the corn meal, that fungus will attack all the fungi it finds. Almost any disease fungi in your soil will be destroyed. In fact the only lawn diseases corn meal does not seem to work on are red thread and rust. With that in mind, you don't have to figure out what your fungal problem is, just use corn meal and it will go away. Two more last things, it takes 3 full weeks for the grass to start looking good again after you apply the corn meal. While the disease will be gone in 10 days, it takes 10 more days for the grass to get growing. The other last thing is that corn meal is an organic fertilizer. You will not have to fertilize your yard after using the corn meal. You should notice that the grass in the areas where you still have grass is much darker and more uniformly green in 3 weeks. I fertilize with corn meal on all the federal holidays. The next ones being Memorial Day followed by 4th of July and Labor Day.

1. Zoysia should only be fertilized 2 or 3 times of year depending on your location and length of growing season. First application is made with a balanced fertilizer like 20-5-10 after the grass is fully greened up in the spring. Second application is 8 to 10 weeks after first application with a nitrogen only fertilizer like 39-0-0 or 34-0-0. If you live on the gulf region you can apply a third application of nitrogen 8 weeks after 2nd application. Zoysia is a heavy thatcher and over fertilizing Zoysia amplifies the problem. 2. Cannot answer without more info, anything would be a guess on my part. 3. Use slow release urea type fertilizers like those from a Lesco dealer. 4. Zoysia is a heavy thatcher and should be de-thatched at least every other year if not every year especially if over fertilized. Core aeration is not real effective with thatch, best to use a rake or power rake (aka vertical mower). 5. Optimum soil PH for Zoysia is a acidic soil of 5.9 to 6.8 favoring the 6.8 neutral side. Only your soil lab tech can tell you what you need.

White roots are healthy roots. Dollar spot is not a killer on Zoysia and can usually be N or fertilized out of. As a former Golf Course Supt. in the Kansas City area I have never treated for Dollar spot on Zoysia. Don't pay for that again. I would suggest a wait and see approach. Put on some old shorts and get up close and personal with the sod. Dig into the worst looking pices to see if there is any green in it. Some life is good and do your best to keep that going until your soil temp droppes.

Do you change your watering in cooler weather? What is your watering schedule? How often and for how long do you water? Also where in Alabama? As you know the climate and soil is quite different from south to north.