It's hard to see exactly, but it looks like grassy weed skeletons. This isn't uncommon at all during the winter. Broomsedge, Crabgrass, and other common native grasses will either go dormant or die off (depending on whether they are annuals or perennials) during the winter. The color of the dead top-growth differs from one grass to another, thus the contrasting color in the spots.

As far as watering, you don't need to water during the winter, and if we continue to get 1" of rainfall or more per week, you won't need to supplement with water in the summer (and believe me, it's hard for a lawn professional to say those words).

I offer fertilization and weed control services, and do-it-yourself homeowners are always welcome to look over my program outline and follow my tips on Facebook as I do seasonal updates.

My first advice is to go ahead and start with a pre-emergent application. Look for the active ingredient Prodiamine, which will have much better results on annual grassy weeds, than the Pendimethalin you find in home improvement stores.

Good luck

Here is a link that might be useful: Program overview

Do you have any pets? Have you considered that dog urine will kill of your grass in a similar manner?

Our grass looked very similar to this about a year ago - our 2 yr old lab was ruining it! We used dog rocks in their water bowl and have had a green lush lawn ever since - if you have a dog - give it a go.

For pre emergent application or starting with early spring fertilizer in the next few weeks (as many resources say), does that still apply to GA? I have also seen things that say dont fertilize Zoysia in GA before May due to potential for large patch or something (which I also thought this could be the start of based off the following post and image: http://www.walterreeves.com/gardening-q-and-a/large-patch-in-zoysia/ )

I dont have any dogs but there are plenty in the neighborhood that pass by, and it is near the curb.

However, I checked the other grass on other side of our driveway (plenty along curb there too) and didnt see any similar marks. Also, none of the other houses seemed to have this, although I did not check close up. Unless this one particular area is the sole area dogs use, I am not sure that is it. Also, back in mid - late fall when we purchased there were plenty of dogs at that time as well but I didnt notice anything.

Large patch is a leaf and stem disease that occurs during warm humid periods. It usually occurs in Zoysia lawns that are over-fertilized with high Nitrogen during periods with frequent evening thunderstorms and night time temperatures over 75 degrees (evening thunderstorms lead to guttation, which gives the pathogen all it needs to spread). If you maintain weekly mowing, avoid watering in the evening, and keep a good balance of nutrients you aren't very likely to see large patch.

As far as pet damage, this isn't uncommon, however the damage would have been done during the growing season, and the discoloration would have been very noticeable. Pet damage is similar to a fertilizer spill in that the urine has a high concentration of urea (nitrogen), which draws water from the root and dehydrates the plant very quickly. I am glad to hear that there is a solution, I was not familiar with dog rocks, so I'll have to look up more information to provide to customers with dogs.

As for Spring fertilization, most granular pre-emergents use Potash as the dispersing agent. Potash improves the cell turgor in plants, making them more drought tolerant and less susceptible to disease. Don't begin Nitrogen fertilization until the lawn is at least 50% green. Zoysia is a low Nitrogen turf, so during the summer, avoid high Nitrogen fertilizer, especially during hot humid periods. Also, use a slow release fertilizer to avoid a burst of new growth. Too much new growth at one time is often all a pathogen needs to get into the lawn.

Here is a link that might be useful: Serenity Lawn Service