Continue to wash the impacted areas down, but don't worry about fertilizing the spot. No need to add any more salts to the affected area. Just re-seed the area, and water the seeds as per their needs.

Firts let me say I hate SA. The Marathon looks like a version of Tall Fescue. My concern would be whether you can give it enough water, especially as it roots. My bias is Bermuda. Very drought resistant.

In your area St Aug would be my first thought. It can take over in my opinion. All you have to do is put down one piece (about a dollar). If you can get Floratam use that but I think all you can find is Palmetto in your area. Put it down onto bare soil and walk on it to get good contact with the underlying soil. Keep it moist for the first 2 weeks until it knits to the underlying soil. Moist means moisten (not drench) it at breakfast, lunch, and dinner. Once it is established keep it just a little bit moister than the surrounding Marathon II. Marathon II is a dwarf type grass. Palmetto likes to be mowed at the highest setting. If you mow your lawn at the highest setting and restrict water to once per week (that is after you are sure your piece of St Aug is knitted down), the St Aug will send out runners in all directions about 5 feet in length once during the warm up in the spring and once again during the cool down in the fall. So you'll get a pretty good coverage. When you fertilize, fertilize only the St Augustine. Drop some alfalfa pellets on the main piece and follow the runners out with more alfalfa pellets. You can do that every week if you like. That will keep the St Aug in the peak of health while allowing the Marathon II to decline. If you have patches of burr clover now, that is right where I would start with the St Augustine pieces. The more pieces of St Aug you start with, the faster this project will be complete. In the really hot and dry summer heat, meaning over 100 every day and humidity below 20%, you should water the St Aug every 5 days. Just to keep the Marathon sort of green, that should probably be watered, too. As the temps cool down, you can favor the St Augustine more and try to get more runners out of it. If you buy one piece of St Aug for a dollar, you can chop it up into smaller pieces with a machete or shovel. I would not cut it into more than four pieces, though. You have to have something to work with. But that would help you get it going farther faster. Generally St Augustine will dominate all other grasses with few exceptions. Some bunch grasses like dallisgrass can get a foothold and move in. Burr clover can be a weed in St Aug. Once you get St Aug, you can no longer use Weed-B-Gone Clover, Chickweed, and Oxalis against broad leafe weeds. WBG will kill the St Aug. You have to use a product with atrazine. You can only use that stuff once per year, so be judicious when/where you use it. Atrazine is a nasty product and repeated use doesn't seem to work as well as the first use anyway. When you spray, walk backwards so you don't have to walk through it. That stuff will flat knock down everything but the St Aug, though. It can take a few weeks, and you'll never really see the weeds withering away until SUDDENLY (!) they are no longer there. I would wait until April when the grass and all the weeds are growing well. Don't spray it now or you might lose your entire lawn. This paragraph is more for next year and the years after once you have the St Aug established. If you are watering and mowing right, you should never see another weed.

Thanks so much! Delivery is slow from home furniture mart, but I knew that ahead of time. It took about 6 weeks to get that piece - but I really couldn't find anything locally that I liked as well. Do check out their coupon page on their site - I got a nice discount that I was going to use to pay for white glove gold service. I did ask for the white glove gold service (bring it in, set it up, remove the boxes). Instead, somehow there was a glitch and it arrived with curbside only. However, the actual delivery men were very nice and did bring it into the den for me. As for following up with funituremart on that $100 service - OMG! It was like that credit card commercial and "Hullough, my name essss Peggy"! "Peggy" obviously could not understand a word I was saying. There is NO WAY that guy's name was "Bob". I then got on the phone with his boss "Russel" (yeah right). He had "Peggy's" accent - I SWEAR I am not making this up. My husband and the delivery guys who were still in the room were actually laughing so hard their sides were hurting in the background listening to us. They did get it sorted out eventually and sent me a check for the $100. So they definitely made it right. We put the unit together ourselves and discarded the boxes and saved $100 in the process. Bear in mind, the furniture did arrive when they said it would, and the unit is gorgeous and very substantially made. I think the whole room now has more of an art deco feel instead of the British Colonial it did have.