A wall isn't the answer when you have a significant proportion arriving legally and overstaying their visas. Workplace enforcement is the only way to stop illegal immigration. Removed the demand for cheap (illegal) labor and the supply will stop coming. Will there be a need for a migrant worker program for Agriculture? Yes, and creating a legal means to enter and exit the US will be its own reward for those workers.
Border enforcement is an important component, but border enforcement first will not be as effective as labor enforcement. Tripling the size of the Border Patrol and still releasing illegals to await an immigration hearing would be a waste of money.
Workplace enforcement is the only way to stop illegal immigration. How to get rid of an ant infestation?
Remove the leaky jar of honey and the box of sugar with a hole in it from the pantry shelf.
Watch the thick stream of ants begin to thin out, and eventually disappear.