Combine the cheese, mayonnaise, garlic and onion powder, cayenne pepper, pimento and jalapeños in a bowl and blend. Season the mixture with salt and pepper, cover and refrigerate it until it firms. Combine the chopped pecans and cooked bacon in a bowl. Roll the pimento cheese into tablespoon-size balls and roll them into the bacon-pecan mixture. Just before serving, put a pretzel stick in each ball.