I would suggest that you find a local special FX / Pyrotechnician as the only way that I know how to do this involves the use of det cord and spark hits, depending upon the actual visual effect desired.
Det cord in powerful stuff and will very easily cut a small tree in half. As such, it should not be used (and in fact should not be able to be purchased) by someone not licensed and properly trained.
In posting this response I am probably bordering on overstepping the guidelines for this forum. Our Webmaster has (very appropriately) requested that we do not provide suggestions or information that could cause injury or even death to someone who may read the information and attempt to apply it. Obviously, there are legal implications that could apply.
When it comes to special effects that use dangerous substances you are ALWAYS best advised to seek out the services of a TRAINED PROFESSIONAL. Sure – you may have to go over budget to get the effect but you are guaranteed of getting the desired results and you are going to have it done in a safe manner. Attempting them yourself will often result in wasted money in not achieving the desired results first time. Also, what value do you place on your fingers, hand, eyes etc and your life.
I hope that this is helpful to you. Whilst I am in Australia, some of the members here from Florida may be able to advise you on how to locate an appropriate person to approach for this project. You could always enquire with the theme parks that have special effects in their shows.