What is a good ground sterilizer that will last at least 2 years?

Answer:

Paramathal

"Paramathal" (pa-ram-ma-thall): It should last about 3 years, but it migrates in the soil. In other words, it travels. So if you use it, it can travel as far as 8' past your target area. Also it will destroy all the rubber gaskets in the equipment you use to put it on with.

One other thing, someone who uses this stuff must be licensed.

Gasoline

Something easier to get, but only lasts a year is gasoline and you don't need a license to apply it... just common sense.

Bromacil

Gasoline is dangerous to apply. Better to use Banish Total Ground Sterilizer containing Bromacil. Very powerful and long lasting. The link is below.