There are a number of fumigants available, all with certain advantages and disadvantages. Several fumigant active ingredients have lost their federal registrations for stored grain in the past few years. If the product to be used is old, check the label to ensure that all ingredients are currently approved for this use.
Fumigation is both complicated and risky and often it is best to leave it to professionals.
Be sure to read and follow all label precautions. The best advice is to follow Steps 1 through 6 closely to prevent the need for this costly procedure.