The Grower

New labor-saving equipment for treefruit and lettuce growers should reach the market in the next two years.

The latest push to mechanize agricultural tasks reliant on a chancy labor supply includes automated insect traps and machines to thin lettuce and simplify apple harvesting. The devices are undergoing modifications based on promising field trials.

Automated orchard traps

Much of orchard scouting currently relies on deploying and regularly inspecting mainly delta traps baited with pheromone lures for specific insect pests—a time-consuming process, particularly with widely scattered blocks. New automated traps could speed that.

The traps are expected to undergo largescale field tests this season for a potential market introduction the following year, says Johnny Park, research assistant professor in computer engineering at Purdue University in West Lafayette, Ind.

The Z-traps—named for the zap delivered to insects that venture inside—identify species through the bioimpedance signal emitted when a specimen is hit, combined with the time of day it’s collected.

Sensors can distinguish between non-target insects and codling moth, Oriental fruit moth and obliquebanded leafroller, and eventually should allow a single trap to use lures for all three.

Using one trap for multiple pests not only simplifies scouting but also boosts costeffectiveness, says Vince Jones, entomology professor at Washington State University’s Wenatchee research center.

“Obviously the technology is not going to be cheap,” says Larry Hull, emeritus professor of entomology at Penn State University’s Biglerville research center. But while manual traps might cost less up front, automated traps pull ahead through overall labor reductions.

An electronic network links each trap in a block, and their GPS-identified data is uploaded regularly to a secure website.

Growers can log in from anywhere using a computer or smartphone, or set up alerts when trap catches reach threshold levels.

“So much of orchard management depends on information that’s time sensitive,” Jones says.

Park also runs Spensa Technologies Inc., a spinoff company bringing the Z-traps to market. The company will release myTraps, an online tool to manage trap data, later this year.

The subscription-based application produces spatial and temporal maps from data from current delta traps or the new Z-traps, he says. Another function will allow growers to store their pesticide application records.

The Z-traps are back in the labs to improve power usage and strengthen wireless and detection systems.

Current batteries last two weeks; swapping in replacements that often cuts into labor savings, Jones says. The goal is batteries that last through the growing season.

Tests show the traps perform at least as well as standard delta traps, Hull says.

Deployment is similar, with the caveat that the Z-traps’ electronics add weight that requires sturdier branches as anchors.

Future developments could add more detectable insects, he says, from natural enemies to a newer orchard threat, brown marmorated stink bug.

Labor-saving lettuce thinning

Labor concerns also drive development of thinning and harvesting machines. Even before the most recent harvest-worker shortages around the country, Arizona’s lettuce industry had pinpointed an aging workforce with few replacements in sight, says Kurt Nolte, director of the University of Arizona’s Yuma Agricultural Center.

“The future is mechanization,” he says.

A lettuce thinning machine developed in part by Mark Siemens, associate professor and specialty crops mechanization specialist at the Yuma facility, makes better use of fewer field workers.

The most recent tests of a 42-inch-bed model thinned 2 acres of lettuce per hour, Siemens says. By comparison, one person can hand-thin an acre in eight hours.

A model twice as wide is in the works for growers planting 84-inch beds, Nolte says.

The machine’s current 1 1/2 mph speed is acceptable for commercial conditions, Siemens says. But he hopes to improve that speed to 2 or even 3 mph in the coming year.

The tractor-towed machine analyzes on-the-go images and determines, based on preprogrammed spacing specifications, which plants to thin with precisely directed herbicidal sprays. The entire operation occurs in one pass through the field, Siemens says.

Computer speed limits how fast the machine can traverse the field. Beyond that, a limited number of herbicides registered for lettuce is the remaining concern.

Sulfuric acid is highly effective and inexpensive, but would need regulatory approval for such a use, he says.

Thinning with herbicidal sprays rather than a mechanical knife reduces the machine’s moving parts and minimizes soil disturbance that would encourage weed growth, Nolte says.

The university has submitted a patent application, aiming to license the technology to manufacturers, Siemens says.

Vacuums help apple pickers

Several companies are developing harvestassist machines for apples and other tree fruit. DBR Conveyor Concepts in Conklin, Mich., is about a year away from bringing a tractor-pulled vacuum harvester to market, says owner Phil Brown.

Additional modifications are planned ahead of a new round of tests in California canning peaches and Washington apples.

“I’m excited by the opportunity to employ a machine like this,” says Brent Milne, assistant orchard manager at McDougall & Sons Inc. in Wenatchee. Last year’s field trials included work in the company’s orchards.

Vacuum hoses connect to a rotating bin filler, all set up between hydraulic platforms that position harvest workers at the canopy. Alternately, platform-based workers can concentrate on the top branches with pickers on the ground harvesting the lower half, eliminating ladder work entirely.

The machine offers opportunities to people unable to climb ladders or hoist picking bags day after day. “That takes the pressure off,” Milne says. “The machine does most of the work of transporting the fruit and the worker is only taking it off the tree.”

A five-week Washington field trial highlighted ways to reduce bruising, the key remaining hurdle, says Karen Lewis, WSU tree-fruit specialist in Ephrata. Modifications include adjusting the fruit decelerator and bin filler, as well as training workers to place apples in the vacuum hose one at a time.

Large and small apples are sucked through the hose at different rates, potentially allowing them to catch up to each other with a bruise-producing impact, Brown says.

Inconsistently sized fruit creates the most problems.

Foam pads the hoses and decelerator. In the Washington tests, sunburn protectants initially clogged the decelerator and reduced its fruit-slowing capacity, Lewis said, but field modifications solved that problem.

A four-hose system can handle 16 apples per second—faster than pickers can work, Brown says. In ideal conditions, the machine can fill a box, offload it and take on a new container in less than 10 minutes. Adding lights would extend the harvest day.

That speed is “absolutely within industry standards for efficiency,” Lewis says.

“A uniform canopy and crop load, with easily accessible fruit, is the key to optimizing almost any level of mechanization,” she says.