The year I graduated high school. Managed a 57 acre Concord grape vineyard, and leased a 5 acre vineyard myself. 

Coca Cola was paying $180 per ton for 16 brix grapes. Since I leased the vineyard too late to do a decent pruning job, I used an experimental mechanical trimmer, that did a half assed job of pruning. I got a yield of around 12 tons per acre, but the sugar was down 12-14 brix and I got docked for lack of sugar.

The 57 acre vineyard averaged around 4 ton per acre with 16-17 brix sugar. The owner purchased a new Mecca Brothers mechanical grape harvester, and I was the operator! We pulled it with John Deere 2030, with rice tires, as northeast Ohio can get pretty wet in October. We did custom harvesting for about 5 weeks that year.

My wages were $4 an hour, to operate the harvester. Often we would work 20 hour days to get 3, 22 ton loads picked. It all depended on the weather, and how often we got stuck in the sticky clay, that most of the vineyards were planted in. Nobody but Deutz made a 4WD tractor in those days that would fit in a vineyard.

I think Concords are still around $180 a ton, which is why most of the vineyards were torn out or replanted to French Hybrid wine grapes, that can be worth up to $2700 a ton!