If we were to use picking fruit as an example, unless the industry was drastically changed and they revamped the wages paid, which would possibly drive up the cost, we would not have enough fruit in this country for the demand. United States citizens generally won't work those difficult and tedious jobs for the extremely low pay.
Yes, I believe a guest worker program will be economical and fiscally sound for our country. It will benefit us in a way of providing jobs to those in need and for people actually accepting the jobs the average American doesn't want to accept. They also may agree to work at a cheaper rate which can also benefit us.