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A new grape leaf puller for vineyards uses pressure sensors to follow the contours of canopies during leaf removal. <b>(Courtesy Vine Tech Equipment)</b>

A new grape leaf puller for vineyards uses pressure sensors to follow the contours of canopies during leaf removal. (Courtesy Vine Tech Equipment)

Harvesters aren’t the only vineyard implements going high-tech.

A pre-pruner uses laser technology for more precise pruning to eliminate the need for follow-up hand pruning, and a leaf puller uses a sensor called a potentiometer that “feels” the canopy to automatically adjust tool pressure.

Both new tools are from Pellenc, a leading French manufacturer specializing in grape equipment, but other companies are working on mechanizing vineyard tasks like shoot thinning, fruit thinning, and canopy positioning.

Pre-pruners of the past were set up like a box with saw blades cutting vertically and horizontally, leaving behind a square bush. Because of variability in height and width of cordons and pruner sway movement on the tractor, pre-pruners have traditionally required follow-up hand pruning.

Pellenc’s new precision pre-pruner uses ten laser eyes to guide top blades and spring-loaded skids to guide side blades, which results in closer cuts than in the past.

Richard Hoff, director of viticulture for Mercer Canyons, Prosser, Washington, used the new precision pre-pruner last season.

“The biggest difference was in the hand labor follow up,” he said. “We were able to consistently cut spurs down to 1.5 inches long, and in some spots, we got spurs down to less than an inch.”

Follow-up hand pruning was only needed for the few canes missed by the blades because they were located near trellis posts. “Workers were able to walk quickly down the rows and prune the one or two canes around posts that are every 20 to 30 feet. It was pretty minimal work.”

While Hoff says there is room for improvement for the pre-pruner, he was pleased with the first year’s results.

Because pruning represents such a big part of vineyard labor, he’s working to eliminate the need for any hand pruning.

He also has one season’s experience with Pellenc’s soft-touch leaf puller that uses a potentiometer as a position sensor to track the canopy and automatically manage tool pressure.

Sensors help the leaf puller’s drums follow the contours of the canopy to cut leaves whole. Most leafing devices rely on the operator to position the leaf-removal tool as it moves down the canopy row.

The leaf puller did a good job of following the canopy, according to Hoff. But he said that in some locations, it wasn’t as aggressive in cutting leaves as a Clemens, a leaf removal attachment widely used in vineyards made by the German Clemens manufacturer.

The cost of the Pellenc precision pre-pruner that can be attached to a standard tractor is around $45,000; a soft-touch leaf puller attachment for a standard tractor is $25,000.  •

—Melissa Hansen