Mechanized Grapevine Fruit Zone Leaf Removal

(latch clicking)

- Until recently, fruit zone leaf removal was primarily implemented by manually pulling fruit zone leaves by hand.

Leaves that surround clusters are removed by pulling the petiole or leaf stem away from the primary shoot, thereby removing the leaf blade in tandem.

In comparison to mechanized leaf removal, manual leaf removal can result in more consistent removal of whole leaves, but this effort is laborious.

Given that fruit zone leaf removal is ideally implemented within a short timeframe between BB-size and pea-sized berries, removing leaves by hand may delay its implementation until mid to late summer.

The well-known phrase necessity is the mother of invention applies here.

The need was timely leaf removal and the invention was tractor-mounted mechanized leaf removal machines that provided a method to remove leaves more efficiently and with less labor.

Mechanical leaf removal is now becoming a popular option in scenarios where value is placed on creating an open canopy fruits zones.

There are two general categories of tractor-mounted mechanical leaf removal machines, pull and cut or pulsed air.

These machine types differ in the mechanism by which they remove foliage from the grapevine canopy.

Both machine types can remove full leaves as well as pieces or parts of leaves, oftentimes leaving the petiole attached to the shoot.

The pull and cut leaf removal machine uses rollers and blades to cut leaves and leaf pieces away from the fruit zone.

The machine pulls the leaves in via the rollers, cuts them as they enter through the machine and then with the aid of a fan, discharges the vegetation out of the front or back of the machine.

The height and angle of the machine head can be adjusted to account for changes in trellis type, trellis height or vineyard topography.

Note that the machine needs to be run very close to the trellis and canopy in order to effectively pull and cut the vegetation.

Its execution requires skillful tractor operation.

The pulsed air leaf removal machine uses strong pulses of air to shred and blow leaves and leaf pieces away from the fruit zone.

The machine has a rotating head with constant air pressure moving through multiple outlets.

The air pressure increases as the air outlet rotates past the canopy-facing metal face of the machine.

These stronger air pulses shred vegetation.

The face of the machine can be rotated along its shaft to adjust leaf removal intensity over different sized portions of fruit zones.

The height of the machine head can be adjusted to account for changes in trellis type, trellis height or vineyard topography.

Similar to the pull and cut machine, this machine also needs to be run very close to the trellis and canopy in order to effectively trim the vegetation.

Here is a before and after of pulsed air mechanized leaf removal with a moderate fruit exposure goal.

And here is a before and after of pulsed air mechanized leaf removal with a more intensive fruit exposure goal.

And here is a comparison of no leaf removal, manual hand removal of two leaves per shoot and mechanized leaf removal with a pull and cut machine.

As you have seen, positioning and tucking shoots in advance will optimize mechanized leaf removal efficacy.

It's also important to properly calibrate the machine and use it in a timely manner.

The most consistent positive remarks about leaf removal mechanization regard the ability to implement leaf removal in a timely fashion and reducing labor requirements and costs.

Beyond upfront expense of the machine, there are some challenges with mechanical leaf removal.

Vineyard topography and row orientation can pose a challenge for machinery.

Fruit bruising and cluster damage is possible with both machine types.

If you are thinking about purchasing a mechanized leaf removal machine, it is important to consider several factors such as the cultivars you grow, the trellis systems on which they are trained, the size and topography of your vineyard, labor costs and availability and your winemaking production goals.

For more information on fruit zone leaf removal and canopy management, please visit the Penn State Extension grape and wine team's website at www.extension.psu.edu/grapes-and-wine.

Thanks for watching and happy leaf pulling.