Indeed, "child labor laws" were expanded to cover agricultural labor in the '70s..Two reasons a) to protect children from abusive labor conditions and b) to provide low-skill employment for adults.  The immigrant field workers filled the void created when working-class anglos decided they didn't want to do the hard labor for the wages offered.  Please also remember only a very few kids, usually from small rural and semi-rural communities (such as Junction City) were involved in this limited seasonal agricultural work.  It was fine for those kids (ours picked beans and berries to raise money for school clothes), but, especially today with machine-picked bush beans and increased automation industry-wide, those jobs are less plentiful.  And yes indeed, Latino workers are great employees.  The show up for work "on time."  They don't come "hung over" or "stoned". The perform the job and work hard doing it.  They're great folks and great workers.....many Anglos could learn a great from them