Question
I LIVE IN LOUISIANA I WANT TO NO HOW TO GET RID OF TORPEDO GRASS AND NOT KILL MY CENIPEDE GRASS?

Answer
Gardenguides.com posts a page on Torpedo Grass ('Panicum repens' to botanists):

http://www.gardenguides.com/plants/plantguides/grasses/plantguide.asp?symbol=PAR...

They state: 'It was once used for cattle in the 1920s and is resistant to grazing and trampling; however, better forages are now available that has higher quality and does not create the potential weed problems that Torpedo Grass did.'

And they also point out: 'Once established, Torpedo Grass is difficult to eradicate...The plant prospers with periodic fire provided sufficient soil moisture is present to avoid scorching root systems. Once established, it is difficult to kill.'

Guess you have a problem.

It gets worse.

The Global Invasive Species Database has this to say about your favorite weed:

'Management of this species involves repeated applications of herbicides. There is very little physical management that can be used to control this species because disturbances encourage its growth.'

My best guess -- I'll look into this further, but right now here's my vote -- Soil Sterilization.

Solarizing is the Intelligent Gardener's Method of erasing all flora and fauna to start from scratch.  It works on everything I know -- but I admit, I have not have a problem with Torpedo Grass.  It bakes everything under heat-trapping plastic.  In theory, at least, this should work.  But if you are growing this stuff in a Swamp, it will have to be dried out first.

Go down to Home Depot or Lowes and pick up your equipment:

(1) several large bags of aged manure, and

(2) several of their biggest, cheapest sheets of clear plastic (found in the painting section).

Back at the ranch, get out the lawnmower and cut down all weeds as close to the ground as you can get.  Then have the whole plot tilled.  You want to dig up all the weed seeds that are lying dormant waiting for next year, or the next year after that, to sprout and ruin everything.

Soak the plot.  The whole area should be one big mudpond.  
That soil should be mud 2-3 feet deep.  Cover, and wait.

If you know a chicken farm somewhere in the area, get some chicken manure.  Horse manure is second best and can be substituted.  For this, you do not have to age it - just remember it will stink to high heaven, so try to get the Chicken manure for a  number of reasons.  On a hot, sunny Louisiana day when the temperatures are beginning to climb into the high 90s, re-water to the mud stage and then cover the entire plot with the clear plastic.  Treat the whole plot - the larger this treated area, the more effective and long lasting it will be.  Keep that plastic down on the ground, trapping the sun's rays and baking the dirt underneath.  Do that for 6 weeks.

If you are really feeling ambitious, you can keep it there longer.

The idea is to get the weeds to germinate so that they are actively growing when the heat strikes them.  

Remove, and see what's left.  Re-till, and re-bake.  Then tell me the results.  God willing, you'll be ready to sow or sod a new lawn.

The concept here, Jerome, is to superheat everything under the plastic.

The moisture generates growth and germination of all the weeds and rhizomes under there that would protect themselves by remaining dormant if they were dry.

The high-Nitrogen manure and alfalfa produce toxins that concentrate under the plastic and boost the power of the
solar heat by several times - this concept was tested and although the explanation is still a theory, the practice worked and is now standard.

Everything growing under the plastic will be history.  When done, you will hopefully be ready to sow on first rate soil with new grass seed.  Do not till the plot after you solarize; this could bring up deeply buried, viable weed seeds just waiting to germinate.  You can purchase top grass seed from Seedland on the internet (www.seedland.com).

You can read one California farmer's experience with Soil Solarization (news.ucanr.org/newsstorymain.cfm?story=699) or the Montana State University Weed Science tip sheet on solarizing soil (weeds.montana.edu/urban/solarization.htm).

I'll keep checking.  And will follow up with more info if I find something better.  Keep me posted. Any questions I'm here.  Great question!