The US is so used to getting lots of food very cheap that the only way to keep that up is either heavily underpaying the labourers or importing it from countries where labour is a lot cheaper to begin with.
If you have a house in the US and have to save up money for your pension then what is currently being paid is not enough by far. The reason illegal immigrants are willing to work for so little is because they would get paid less at home and by living in crappy conditions they can save up money to send back home or to save up to have some when going back.
For US citizens however there is no going back to a different country after working a while, they have to pay a lot for their families to have a decent life and therefor they'd need a decent salary.
You basically have 3 options. The first one is paying more for food and having less left for other things (which won't be popular with most of the population), the second is to heavily subsidize agriculture, but that means taxes won't be lowered the first while, and the last is to end all non-competitive food production and import it all. Which means the US becomes fully dependable for most of the food on foreign countries. Which opens the way for those countries to wait a few years for the infrastructure to produce certain food items to vanish in the US and then to slap an export tax on it.
I'm happy to see what no matter which route Trump and friends take it will piss off most of the US. Either they have to pay more for food, jobs will be 'exported', or Trump will have to break another promise.