Harvesting Hazelnuts Mechanically in the Midwest
Harvesting hazelnuts by hand is doable at a small scale, but more than an acre or so and your friends and family stop answering the phone when you call looking for help, especially as the plants get taller than you. If there is an abundant supply of inexpensive labor, hand-harvest might be commercially viable, but only then. So, that means harvesting with machines. This page is dedicated to mechanical harvesting.
Existing Harvesting Methods
Hazelnuts are new to the Upper Midwest but they've been grown commercially elsewhere for more than 100 years. Generally, hazelnuts are allowed to drop to the orchard floor where they are swept or vacuumed up, hauled to a cleaning facility, and dried for storage. There are three primary downsides to orchard-floor harvesting: rain during the harvest season means mud and possible nut loss, intensive orchard-floor management is expensive with negative environmental impacts, and sweeping off the orchard floor means dirt, debris, and contaminants must be removed after harvest. The primary advantages are that plant size doesn't matter, the nuts aren't lost if they drop from the trees, and there are many proven options for ground-based harvesting, some of which are shown in the videos below.
Hazelnuts are new to the Upper Midwest but they've been grown commercially elsewhere for more than 100 years. Generally, hazelnuts are allowed to drop to the orchard floor where they are swept or vacuumed up, hauled to a cleaning facility, and dried for storage. There are three primary downsides to orchard-floor harvesting: rain during the harvest season means mud and possible nut loss, intensive orchard-floor management is expensive with negative environmental impacts, and sweeping off the orchard floor means dirt, debris, and contaminants must be removed after harvest. The primary advantages are that plant size doesn't matter, the nuts aren't lost if they drop from the trees, and there are many proven options for ground-based harvesting, some of which are shown in the videos below.
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Small-Scale Vacuum Harvesters
Expensive machines don't work in all circumstances such as on a steep slope or at a small scale where expensive machines are unaffordable. A next step up from hand-harvesting are various versions of PTO-driven harvesters that combine hand-held vacuum hoses with de-husking and winnowing such as shown in these videos. They are most effective when the ground vegetation is well-mowed, the base of the hazelnut plants are accessible, and the clusters are nice and dry. One big advantage of these machines is they are relatively mobile and can be trailered or towed from farm to farm.
Expensive machines don't work in all circumstances such as on a steep slope or at a small scale where expensive machines are unaffordable. A next step up from hand-harvesting are various versions of PTO-driven harvesters that combine hand-held vacuum hoses with de-husking and winnowing such as shown in these videos. They are most effective when the ground vegetation is well-mowed, the base of the hazelnut plants are accessible, and the clusters are nice and dry. One big advantage of these machines is they are relatively mobile and can be trailered or towed from farm to farm.
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Over-The-Row (OTR) Harvesters
The mechanical harvesting system envisioned for the Midwest is harvesting the nut clusters directly from the hazelnut plants using over-the-row harvesters that shake the clusters and nuts off the plants, collect them, and off-load into bins. This work has been pioneered by early-adopters using old model OTR harvesters originally built for small fruit, such as blueberries. OTR harvesting of hazelnuts is still very much in the experimental stage, but companies and researchers are looking at it here and in major production regions like Oregon. The University of Wisconsin did quite a bit of work evaluating these machines. Take a look at what they learned.
The mechanical harvesting system envisioned for the Midwest is harvesting the nut clusters directly from the hazelnut plants using over-the-row harvesters that shake the clusters and nuts off the plants, collect them, and off-load into bins. This work has been pioneered by early-adopters using old model OTR harvesters originally built for small fruit, such as blueberries. OTR harvesting of hazelnuts is still very much in the experimental stage, but companies and researchers are looking at it here and in major production regions like Oregon. The University of Wisconsin did quite a bit of work evaluating these machines. Take a look at what they learned.
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UW Mechanical Harvesting Presentations
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The Many Variables Affecting OTR Efficacy
Harvest Timing and Detachment Force. OTR harvesting depends on harvesting when the nuts are ripe but aren't yet dropping, and detachment forces are sufficient to shake off the clusters without damaging the stems. Just how wide the harvest window is depends on genetics and ripening. Experience has shown that for some cultivars it can be a matter of days.
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Catch Plates and Plant Width. OTR harvesters depend on the fish-scale catch plates closing in under the plant as the harvester travels down the row. Multi-stem shrubs in a dense hedgerow prevent the catch plates from closing resulting in nuts falling through to the orchard floor, or worse yet, getting caught up in the plant base.
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Plant Size. A wide plant such as in this photo will get compressed into a dense wall of stems and leaves as it passes through the machine resulting in much less force being transmitted to the clusters. This means they don't get knocked off and those that do get hung up in the plant rather than dropping to the catch plates. The tops of plants that are too tall get bent forward and can drop nuts out in front of the catch plates or don't get harvested at all as the stems ride along the harvester tunnel above the shaking action.
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Machine Size. A larger machine can handle bigger plants and move faster. The heavier weight may lead to compaction or rutting in wet years. Also, OTR machines are 10' or more wide and often 13' or higher, requiring low-boy transport. Thus, moving the machine from farm-to-farm can be a challenge.
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Rotary vs Slapper. Slapper type units have rows of horizontal bars that compress the plant as it shakes it. This can perpetuate the compression problem, especially with wide plants. A rotary shaker such as in this photo can penetrate the plants better, don't compress the plant, and generally deliver a more targeted shaking force to the clusters.
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Plant Size Management. OTR harvesting will almost certainly require pruning of some kind to maintain a plant size and form that is optimized to the machine but doesn't reduce yields. Exactly how and when to prune is THE biggest question facing researchers working on OTR harvest right now.
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