Mechanical Harvest of Hedgerow Hazelnuts

 Anyone that has hand-harvested hazelnuts, or worse yet, paid someone to hand-harvest hazelnuts knows it is not a viable option for commercial nut production.  Even the fastest pickers are too slow and too expensive.  In Oregon, hazelnuts drop to the orchard floor and are mechanically harvested by blowing them into windrows and using vacuums or sweepers to pick up the nuts.  This is not an ideal method as it requires considerable management of the orchard floor (herbicides and scraping) and depends on a dry harvest season.  The production model being used in the Upper Midwest is based on harvesting the nut clusters directly from hedgerows of shrubs with over-the-top harvesters as is done with many different small fruits like blueberries and aronia.

Some early-adopter growers have been using BEI blueberry harvesters using slapper-type harvesting heads with good results.  To support these efforts, our research team was recently awarded grant funding from the USDA to evaluate different harvesting equipment and design and build a prototype optimized to hedgerow hazelnuts.  The ideal machine will remove only the ripe clusters from the bushes and do little to no damage to the wood or catkins.  In addition, the machine will separate the in-shell nuts from the husks in the field as part of the harvest process.  Oh, and the machine will be as safe, fast, and cheap as possible.

Most of the work on this grant project will be done in 2019, but thanks to some gracious collaborators we were able to evaluate some equipment this week on plantings in Wisconsin.  These are intended as the first of many harvester evaluations. ​It is important to note these are only preliminary observations of two possible harvest systems and are not intended as an endorsement or criticism of any single harvester unit.  We have not yet conducted formal trials.  If you have harvester ideas or suggestions, we'd love to hear about them.  Contact Jason Fischbach at [email protected].

Weremczuk Joanna 4
The first machine we looked at was a Weremczuk Joanna 4 harvester primarily used with aronia berries.  It works by bending the shrub to roughly a 45 degree angle into the rotary shaker head that uses both fingers and vibration to remove the nut clusters.  We were most interested in this unit because it is designed to harvest half a row at a time and, thus, can handle wide hedgerows.  It does so with a wedge-nose out front of the unit that wedges half of the stems away from the center of the row and into the shaker head.
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The harvesting action was very effective at removing the nut clusters, but it did break some branches and remove some catkins. The wedge-nose that bends over the branches also caused some damage to the bark along the lower stems.  Mechanical harvest by any means will result in some damage to the plant, and such damage is offset by the cost-savings of the mechanized-harvest compared to hand-harvest.  However, it seemed this unit was causing too much damage.   Some slight modifications to the unit, such as a wider throat opening would likely reduce damage.  We operated the unit at roughly 0.3 mph, which is also slow.

The plants we were harvesting are located in Stoughton, WI and are a mix of full-sibling hybrids and pure American hazelnut seedlings planted in 2011.  As such, every plant is genetically and phenotypically unique, as is evident in the videos.  In addition, these plants have not yet been pruned.  Commercial hedgerow hazelnut production will likely have more uniform plant material and pruning will be implemented to facilitate the specific harvest system, meaning any harvest unit will work better when the plants are managed specific to the unit.

​BEI Slapper-Type Harvester
There are at least 2 BEI harvesters being used by hazelnut growers in the Upper Midwest and we were able to view one in action this week.  The BEI harvesters are still being used by blueberry and aronia growers in the Upper Midwest though BEI is no longer in business.  These harvesters work by shaking or slapping the nut clusters off the branches as they pass over the shrubs.  The nut clusters are collected at the bottom of the outside walls and moved out the back of the machine into bins.

The slapper-type head in the BEI unit is much less aggressive and results in less damage to the plants, but it did not remove all the clusters, particularly in the middle of the wider plants.  A more aggressive setting on the slapper bars would likely improve the detachment percentage.  At 48" tall and 72" high, the tunnel is able to accommodate fairly large plants, as long as the stems are supple enough to bend and not break when passing through the tunnel.  The unit shown was travelling between 0.8 and 1.0 mph.  This particular planting is roughly 12 years old and had much lower nut production this year compared to previous years.  The plantings in the Upper Midwest (as with the one shown in the video) consist of genetically unique seedlings resulting in a wide variation of ripening times among the plants.  In addition, within a single plant, the cluster detachment forces can vary significantly among the clusters as they ripen.   For this reason, the plants are harvested 2-3 different times with the slappers set at a fairly gentle setting to harvest only the ripe clusters while minimizing damage to the plants.  Although the aggressiveness of the Joanna 4 unit can be adjusted, it likely is best used as a single-pass unit given the damage that it causes.  The slapper-type action appears better suited for the multiple-pass approach required in the diverse seedling plantings. More uniform plant material would likely reduce the number of necessary passes, and, as with the Joanna 4, using plant material and implementing pruning strategies specific to the harvest unit will increase effectiveness of the harvester.

With over-the-top harvesting in mind, our UMHDI breeding program has been focused on developing relatively compact plants with early high yields.   Combined, those two attributes will help keep the plant size manageable and easier to mechanically harvest.

- Contributed by J. Fischbach