They dont get welfare.
Farms are heavily dependent on immigrants, mostly illegal immigrants from mexico (90% are foreign born) for crop workers. They work on our farms for very little pay (but probably more than they would have in mexico), work here for 10 years or so saving as much as possible, then go back to mexico. They may travel from CA > WA through the season; or on the east: FL > OH > ME (this prolongs their work season). They're on average very poor, with little education (6th grade is the average).
With the more recent restrictions on the flow of illegal migrants, many are finding it's impossible to come back to the us (or they choose not to come back). Disrupting the flow of illegal migrants that the farms depend on.
That is the source of the labor shortage that the farms are now complaining about.
Essentially for years they have taken advantage of illegal immigrants to depress wages in their industry. And now they have been cut off, and theyre finding it difficult to adjust their wages to appropriate levels so they can compete in the domestic labor market.
Farmers deserve no sympathy for the labor shortage.. it's an exploitative arrangement. They should automate as much as possible, and for everything else they should pay market rates (whatever those may be... even if it's $100/hr or more (remember its short term hard labor, 2nd most dangerous work in the US)).
This shortage is actually a great thing, if it lasts. Whatever workers are left, might finally get paid a livable reasonable wage.
Edit: if your curious about their conditions, here's the National Agriculture Workers Survey that covers all of this:
https://www.doleta.gov/agworker/pdf/NAWS_Research_Report_12_...
It's currently "offline for maintenance", so here's google's cache:
https://webcache.googleusercontent.com/search?q=cache:HiRr7h...