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Growers around the world have been resistant to stem-clipping, mainly because of the efficiency costs. Penn State University did a basic study on stem-clipping which estimated that your per-worker production, picking hourly, goes from about 15 bu/hr down to 10 bu/hr when stem-clipping. There is much variability with regard to variety, tree size, level of selectivity, crop load, picking method, etc. but it's a rough estimate and the important thing is the comparison to stem-clipping. Essentially, the slowing to 10 bu./hr translates to a 33% loss in efficiency and a ~50% increase in picking costs per bushel. Assuming an average wage of $15/hr, that is 50 cents increase in picking costs per bushel. Is it worth it?
I worked on the farm for seven years before moving over to the packing house (Rice Fruit Co.) in early 2014. Since then I have been working in quality and I have seen first-hand what stem punctures do to the fruit. The damage happens in the bag, in the bin, on the line, even in the box. If the growers are not stem-clipping then there is no control for the damage, unlike the many other controls that they exercise in the field or in the packing house. As far as direct damage to the fruit, I often see as much as 8% in tree-run bins. There are a lot of risk factors there by variety (shape, thickness of skin), also fruit set and thinning profile (king buds have longer stems) and maturity (less mature fruit = more pulled spurs = deadly). The 8% doesn't account for any secondary losses from rots that have a point of entry in puncture wounds. Also, that 8% can double if you presort. But most packing houses don't presort Honeycrisp and stem punctures are one of the considerations in that decision. That is an opportunity cost.
If you figure that Honeycrisp could be worth $25/bushel return to the grower as an average across the season, then the avoidance of 8% damage is worth the extra cost as long as it doesn't slow you down so much that it delays your picking schedule, which is also weather-dependent and labor-dependent.
So, let's assume a 50% packout into XF for Honeycrisp across the season. For starters, your gains for stem-clipping on tree-run fruit go down conservatively to 4% on account of the likelihood that the damaged fruit wouldn't already be downgraded for some other reason. 4% of $25 is $1. So, in the case of Honeycrisp; yes, it is definitely worth it. It is also worth it to the packing house which makes most of its money on XF boxes and it reduces the pressure for secondary storage issues and helps to avoid costly repacks and rejections.
But why can't we improve on that 10 bu/hr? In this technological era, with so much engineering and data dedicated to the task of optimization, why have we not solved a problem that is so simple, which is simply to shorten the length of the stem before it goes in the bag?
Seeing no solutions, I set about to solve that problem myself about five years ago and I have made a lot of progress. The endeavor has been propelled by a mixture of restlessness and audacity. If we can get up to 12 or 13 bu/hr then the increased cost over conventional picking is only 15-25 cents per bushel which throws it wide open for other varieties like Gala and Fuji and the many branded varieties in the market now. These numbers assume spot-picking by the hour, which is the standard in many places for Honeycrsip, Gala, and some Fujis. Regardless of your harvest practices, if you are intending to clip stems, there is no more efficient method than StemPunk.
To put a hard number on it...using conservative figures mentioned previously in this paper, punctures cost the industry around $2,000 per worker per season, simply in terms of direct damages to apples. In terms of worker productivity, as a direct comparison to clipping by hand, growers would be saving at least $0.25 per bushel in harvest costs (12 bushels/hr up from 10 bushels/hr). Even if a picker were only stem-clipping a third of the days during the season, growers would recoup a combined ~$800 per worker, per season, by using StemPunk instead of hand clippers, meaning that the device pays for itself in a matter of weeks. And those savings extend further if growers use the efficiency gains to optimize harvest schedules and expand stem-clipping to varieties that were not clipped previously.
The other big advantage of StemPunk is the avoidance of clipper punctures. Because the shape of the blades is conical and matches the inside of the stem bowl, you don't get the pokes and jabs which cause the exact problem you are trying to avoid by clipping stems.
Finally, I will point out that I frequently interact with groups who are promoting complex, high-cost solutions to complex problems in the orchard an in the packing house. I pride myself on offering a simple, low-cost solution to a simple problem. Oh, and I promise there is no app that goes with this one...at least not yet.
- Leighton W. Rice
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