Time to Prune?

"Mechanical" versus Hand Pruning

Sandhill cranes in Los Lunas ASC vineyard, December 9, 2019

                 The sandhill cranes (Antigone canadensis) are in peak presence here at the Los Lunas Agriculture Science Center experimental vineyard. Their annual migration is a form of phenology, that describes the repeating/recurring life cycle events of living organisms, that include a wide range of creatures and plants, ranging from the aforementioned cranes to grapevines. Because the crane migration occurs in the fall, it reminds me that pruning time is fast approaching. I am not convinced that we should start pruning just yet, but in conjunction with Santa Ana Pueblo vineyard manager, Mr. Jim Peterson, we have initiated an evaluation in the Santa Ana Vineyard of "mechanical" and hand pruning. The study will be conducted this pruning season (2019 to 2020). There will be three "treatments" imposed on the vines at pruning:

1. Mechanical pruned only with a motorized hedge trimmer.
2. Mechanical pruned with a motorized hedge trimmer with hand-pruned 'follow-up'
3. Hand pruned to 3 bud spurs across the entire vine

                  The bud counts on treatments 2 and 3 will be leave approximately 60-70 buds per vine. Or ~30 buds per side of the vine (~30 buds is about ~ 5 buds per foot given the in-row or intra-row spacing at this vineyard). The mechanically pruned vines with no hand-pruning followup, will have many more than 60-70 buds per vine.

This is substantially heavier than when pruning vines for high-quality still wines. This high bud count will undoubtedly lead to a fairly congested canopy next season with a likely chance of over cropping. But, keep in mind, these vines are destined for sparkling wine and are picked relatively early. Jim and company are aiming for ~5 tons per acre. Jim is looking to gain a time/labor savings with the incorporation of this limited 'machine-aided' pruning. As the rough 'mechanical' pruning is performed, the cut canes and cane fragments fall out of the trellis to the vineyard floor. This alone, saves the pruners from having to "pull brush" from the trellis wires and should ease the strain of constantly pulling brush free of the trellis foliage wires. Check out the following photos to see some of the aspects we are observing as we go along.

The cut end of  'mechanically' cut spur, pruned with a motorized, hand-held, hedge trimmer (left) and the much cleaner cut-end of the spur that was made with sharp hand-pruners (right).

This is a vine that has been 'pruned' with the motorized, hand-held, hedge trimmer.

This is the same vine visible above, 'pruned' with the motorized hand held hedge trimmer  and then cleaned up and adjusted with hand pruners. 

Stay tuned to see the study as it unfolds and what we find out.