Crabgrass in Centipede

[crabbyyard]

Centipede lawn in Alabama, with large swaths of yard with about 50-100% crabgrass. Additionally, last year I didn't water and had two large fairy rings or brown patches (perfect circular growth with discolored edges that grew to about 15' in diameter) which killed 25-50% of grass.

This year, I applied Dimension preemerg in late Feb-early Mar. Then applied Heritage G Fungicide 3 times (about 4 weeks apart) after green up.

I applied 1lb N per 1000 sqft (Scotts Weed and Feed 29-1-10 was all I could find with low P locally) after green up in May and have about 75% of yard with healthy centipede. I recently had spots in yard that had yellowing so applied chelated liquid iron about 1-2 weeks ago, which turned grass dark but is now returning to normal color after successive rains.

I'd like to apply a post emerg to the areas of yard with crabgrass, as I think they will continue to dominate as I applied a preemerg and they still greened up (4 or 5 tillers). I've been hand pulling the seed shoots and bagging my lawn clippings. After reading this site and greendoc's posts, I plan on using Vantage applied at 0.5-.75 oz per gal per 1000 sqft.

Is there any other things I should be doing to help the centipede out compete the crabgrass? We have had a fairly wet spring, so I have only been watering the portion of the yard which had fungal problems, and I overseeded this area with Tifblair centiped, and now I have some good looking, blue green centipede in this area, but also bare spots and areas dominated by crabgrass.

Lastly, before applying Vantage, I read that I should prep the yard with a liquid fertilizer (1/2 lb of N from ammonium sulfate, 1/2 lb of K from potassium nitrate and soluble iron/manganese). I would like to buy the raw materials and mix myself, but I'm thinking that only commerical tank mixers can provide sufficient agitation for dilution. All I have is a Chapin Pro backpack sprayer, so should I just stick with granular fertilizer and spreader or is there a good premixed liquid fertilizer I can buy online?

Thanks for any help.

[crabbyyard]

Photo 1 is typical area with crab grass outcompeting.

Photo 2 is remaining dead spot with crab grass.

Photo 3 is healthy centipede.

Photo 4 is heathy centipede with crab grass in foreground.

[windflower]

That's a lot of stuff on a grass that generally likes to be left alone. I'd not apply any N now and wait on the vantage, you can apply it later if needed.

[dlh2]

Yep, be careful with centipede, it does not like a lot of fertilization. Too much and you will get centipede decline after a few years. I put down 0-0-7 Atrizine (a pre emergent) all over the yard and spot treat the areas where I have a crab grass or Poa Anua problem with Halts sometime in Dec, Jan or Feb depending on how cold or mild the winter is. After it greens up usually around April, I apply a Centipede Weed & Feed (preferably 15-0-15 with Atrizine). Then in mid July, I put down another light feeding of 15-0-15 Weed & Feed for the late summer weeds like Chamber-bitter.

[crabbyyard]

Acknowledged on the over-fertilization. I'll take it easy and just go after the undesirables with Vantage.

Thanks for the replies!