You can solve this easily if you fine the employers who hire them... If you need leaf blowers and bean pickers you can issue them temporary work permits .. Just about every country does that.
Including us.
We do more for outsiders than any industrialized country in the world. There are estimates as high as 30 million illegals in this country, and they all can't be working illegally. They come here for a variety of reasons, not just getting jobs.
In our system of law, they have to prove that the employer knew he or she was hiring illegals in the first place. With all the fake documentation around, it's almost impossible to do. But..... if we stopped them from coming here in the first place, an employer can't hire people who are not here.
Bring Trump back, and the wall continues to be built, Stay In Mexico policy is enacted again, Catch and release is the way of the land, and we get this problem under control.