Answer: The one thing we have found to be effective on fire ants is 2 table spoons of Palmolive liquid dishwashing soap in a gallon of boiling water.  Pour this directly on the mounds.  The way we got control of them was to start around the house and kill the beds out.  Then work out in a circle from there.  It is best if you do this after each rain that is heavy enough to make the ants bring their eggs to the top of the soil.  That way you kill the present generation and the next one also.  It takes a while, but you will begin to notice a difference very soon in the amount of ants around.  You will never kill them all out as it would take everyone in the state of Texas to kill them at the same time.  One mound of fire ants can have as many as eleven queens laying eggs at the same time and each queen can lay over 100,000 eggs.  So we have to get the queen and the eggs to do any good.  Boiling water goes into the mound and kills the queen.  The soap helps the water move quickly into the ground and also adheres to the ants.  When you get them under control in a certain area, broadcast diatomaceous earth over the clean area just as soon as possible.  This stops further infestation.
For the okra, I would recommend spreading diatomaceous earth at the base of the stalks immediately.  They can't crawl over the diatomaceous earth.  It is so sharp it cuts their legs off and kills them. 

Good Luck!

Byron Tumlinson

T-N-T Farm