Irony of counties where the harvest is needed
The writer ironically criticizes the counties' nonchalant treatment of the migrant workers. These counties require the harvest of their crops for their agriculture to survive and therefore their economy maintained so they depend on these migrant workers. But, as the writer suggests, they seem terrified to provide any aid to the labour that they depend on.
Irony of large ranch owners
The large ranch owners treat the workers inhumanely and they forcefully and violently shut down any sign of the workers organizing for their own protection. They know that if the organization is successful they are going to have to treat these people as people with proper wages and proper living conditions.