Labor accounts for a significant portion of the production costs of most fruits, including grapes. For this reason, the recent plan approved by California state lawmakers to increase the minimum wage to $15 per hour by 2022, has grape growers looking to implement practices that reduce labor needs and improve productivity.
Mechanization Motivation
Not all raisin grape vineyards are well suited to mechanical harvest, and those that are require special production practices and/or new grape vine varieties to optimize mechanization.
Therefore, machine harvest has not been as widely adopted in raisin grapes as in winegrapes but, even so, perhaps 50% of California’s raisin crop may eventually allow for mechanized picking of whole clusters, and the use of certain plant growth regulators could possibly allow machine picking of individual table grapes.
Machine-Pruned Vines
Most raisin grape varieties are cane-pruned, a practice that is much harder to mechanize than spur-pruning. Therefore, raisin grapes are generally manually pruned.
Table grapes, even spur-pruned varieties, are also mostly hand-pruned, though I have recently seen a table grape vineyard being pre-pruned by machine. If this method proves successful, other table grape growers are likely to adopt it.
Machine-pruned vines are prone to overcropping since they typically retain more nodes than hand-pruned vines. That’s why it’s common to use a machine to pre-prune wine grapes, and a labor crew to finish the job.
A less laborious option would be to prune entirely by machine and follow up with another machine in the spring to shoot-thin. So far this practice has not been widely adopted, but research has shown that it is a viable option.
Mechanical Leafing, Suckering
Leafing is another potentially beneficial canopy management practice that can be done mechanically.
Sucker removal can also be done by machine. Further labor savings may be gained by coming innovations in mechanization, including driverless smart sprayers.
Productivity can also be increased by improving management precision. Developing tools that grape growers can use to better implement precision management practices is the focus of a new multi-institution research project, including faculty from Carnegie Mellon, Cornell, and the University of California, Davis, and supported by a Specialty Crops Research Initiative grant.
The project seeks to develop real time imaging sensor technology to estimate crop load and assess canopy characteristics.
This data could be used to apply differential management techniques to improve crop yield, quality, uniformity, and to better manage labor.
