Courtesy of Carol Ann Miles
MOUNT VERNON, Wash. — Apples are a notoriously labor-intensive crop. Prone to bruising, they must be hand-harvested, a proposition that becomes more challenging — and expensive — by the year.
For cider apple growers, however, a solution may be on the way: mechanized harvest.
At Washington State University’s Mt. Vernon Northwestern Washington Research and Extension Center, Carol Ann Miles is developing a whole-orchard plan for thinning, pruning and harvesting cider apples mechanically.
Inspired by technology used by the Northwest raspberry industry, Miles’ system uses an over-the-row mechanical harvester that gently shakes apples loose using rotating and vibrating rubberized metal fingers. The apples are then transferred to the down-belt, a conveyor belt that goes straight into the back of a truck driving alongside the harvester.
To work within this system, orchards must be specially planted in a fruiting wall configuration, with all trees on the same rootstock and pruned to a 10-foot height and uniform width. Rows must also be spaced to accommodate the machinery and truck. Miles says her NWREC test plot is planted on 12-foot spacing, but 15-foot may be more appropriate.
Mechanized harvest has so far remained out of reach of the dessert apple industry, but Miles thinks cider apples present more opportunities. “All mechanical harvesting will result in 100 percent bruising,” says Miles, noting that a bruised dessert apple loses virtually all of its value.
Cider apples, on the other hand, are able to sustain bruising without negatively impacting the quality of the finished cider. The WSU team conducted several trials comparing cider from hand-harvested, unbruised apples as well as mechanically harvested, bruised apples and found no significant difference in flavor.
In Europe, all cider apples are mechanically harvested using shake-and-sweep systems. While those systems are effective, they are not compatible with the U.S. regulatory environment or industry structure.
Fermentation is widely observed to eliminate all potential pathogens picked up by soil contact, but in the U.S., most commercial presses produce juice for the fresh market as well as the cider market, which means cross-contamination could become an issue.
“Anybody who’s on a large-scale press is not going to take fruit that’s dropped to the ground for food safety reasons,” Miles says. “The risks are enormous.”
The system presents other advantages in addition to keeping fruit off the ground. Cider apples can be much smaller than dessert apples, which means they take up to four times longer to harvest than larger fruit destined for the fresh market.
“Nobody wants to hand pick a crab apple,” Miles says. “But a crab apple in this kind of a production system would be incredibly productive and would give a really high shot of tannin into a fermented product that was being worked on. So I see this as a really good system for a small-fruited apple.”
So far, trials at NWREC Mt. Vernon have been successful. Right now, the over-the-row harvesting equipment used by Miles and her team is manufactured by Littau, an Oregon company that specializes in equipment for the soft fruit industry. The harvester is prohibitively expensive for most growers to purchase outright, but Miles sees potential for grower cooperatives to rent or share equipment, much like European vineyards.
“England has been working on an over-the-row harvester for a decade or more, and hasn’t gotten there yet” says Miles. “I personally think we’re much farther ahead with this technology than England is.”
The team plans to issue an extension bulletin in late 2018 with a full report on their findings and a comprehensive practical plan for growers. WSU also recently received a grant from the Washington State Department of Agriculture to perform a cost-benefit analysis of mechanization in small, medium, and large-scale orchards.
For more information about WSU’s cider apple mechanization research, visit www.cider.wsu.edu/mechanical-harvest/