10 Jun 2020



Softer landing for fresh blueberries : systems for mechanically harvesting fresh blueberries that are more oriented towards the fresh market could reduce labour costs and bruising.

As the blueberries boom in the United States encounters a shrinking and expensive labour market, more and more growers are seeing cost-saving opportunities in machine harvesting fresh fruit from the market - with machines traditionally used to pick berries for the industry able to handle a bit of bruising.

But there is a problem: the damage that occurs during harvesting can reduce sellable production yields and deteriorate post-harvest quality.

"At the moment, if we use the regular harvester, about 60% of the berries are damaged. If they can sell them in three or four days, a week, that's fine," he said. "But Oregon is an export-oriented industry. We need quality; we need those fruits to be able to keep them for a longer period of time," he said.

An experimental blueberry harvester outfitted with soft-catch plates (the off-white material) designed to reduce bruising stands ready for a harvest trial in 2019 at Washington State University's Northwest Research and Extension Center. (Courtesy Lisa DeVetter)
An experimental blueberry harvesting machine equipped with soft catch plates (the off-white material) designed to reduce damage is ready for a harvesting trial in 2019 at Washington State University's Northwest Research and Extension Center.

Wei Qiang Yang, associate professor at Oregon State University, and a team of researchers across the United States began working on soft-catch technology for blueberries for the fresh market in 2015, and this season, several Northwest growers will be experimenting with over-the-row pickers equipped with materials that reduce impact and improve final yields. This is the first of several innovations needed - including improved breeders and cultivar-by-cultivar prescriptions for best harvesting practices - to automate the production of high-quality fresh blueberries .

"It's an important way to help profitability, to be able to machine harvest blueberries fresh from the market," said Lisa DeVetter, an agronomist specializing in berries for Washington State University and Yang's collaborator on the project. "When we look at the economics, it's pretty compelling: Even these expensive harvesters eventually pay forthemselves."

Lynden, D.C.-based equipment manufacturer Oxbo International partnered with the researchers after a federal grant-funded effort showed promise for soft-capture materials in a harvest aid project using portable agitators, Yang said. In recent seasons, Yang and DeVetter have been testing better and better prototypes, in collaboration with Fumiomi Takeda, a U.S. Department of Agriculture scientist based at the Appalachian Fruit Research Station in West Virginia. His work with a sensor the size of a blueberry that records impact forces has helped guide the harvester's modifications.

Current research funding comes from Specialty Crop Block Grants in Oregon and Washington, in addition to funding from the Oregon Blueberry Commission and the Washington Blueberry Commission.

Oxbo has modified its over-the-row picker by replacing the hard polycarbonate capture plates, the main point of impact, with softer materials that cushion the fall of the berries. These soft materials are also added at other impact points within the harvester. The exact composition of the materials is proprietary and still under development, in terms of food safety and durability.

"I think we have something we are really proud of, but it is not an easy solution," he said. Harvesting blueberries is complicated - different cultivars have different times and stops - and there is no single roadmap to mechanically optimise results. "Our idea is to work with grower partners this year to see how willing they are to modify their operations to (increase the amount of fruit) we can mechanically harvest for fresh," he said.


Mechanical harvesters comprise just one piece of a complicated production chain at blueberries, from seeding and pruning to sorting and shipping, all of which play a role in making mechanisation successful, Van Weerdhuizen said.


In a 2016 survey of blueberries growers across the United States, one-third reported trying machine-picking fruit for fresh markets, and 80 percent said they had concerns about the quality achieved by mechanical harvesting. But rising labour costs leave growers with little choice. In 2019, the U.S. Department of Labor issued a 50 percent mid-season wage increase for blueberries pickers on an H-2A contract.

"It's one of those turning points where the concern for the work we've had for a long time has finally arrived," said Van Weerdhuizen.

For some firmer cultivars, the existing technology works pretty well, said DeVetter. For others, growers could machine harvest a clean crop for the industry after hand-picking the first crop for the fresh market. The successful incorporation of the new soft harvesting technology will need to be combined with a better understanding by researchers and growers of how best to use it, DeVetter said.

"Surely we'll see increased quality, we'll see better packout simply by changing the forward speed and shaking speed," he said. But it all depends on the varieties: the firmness, the pace of ripening, the optimal maturity, the number of steps needed are all different. "I think we can get to a point where we have specific recommendations for the variety," he said.

This is one of the research objectives for this season, now that several commercial growers will be using mechanical harvesters throughout the season.

The experimental harvesting machine is shown in action as the blueberries are collected in capture containers.

Yang and DeVetter also have ongoing research projects on the packaging side, looking for new tools to assess fruit quality beyond firmness. Dents spread quickly in some cultivars, less so in others, which can lead to large quality differences in exported fruit, Yang said.

"The message is that the machine harvesting for the cooler can only be done with a good machine," Yang said. "We know that the new machine will reduce fruit damage with the soft harvesting surface, but the goal is to first reduce internal damage and then work with the packaging line to improve the sorting process.

New harvesting and packing technologies are likely to lead the industry to move towards cultivars best suited to mechanised production systems. Growers have these attributes in mind now, along with flavour and firmness, DeVetter said. He is part of a new national research team developing DNA tools to accelerate varietal research for blueberries and cranberries.

New cultivars that bruise less easily or can be harvested in fewer steps would be ideal, Yang said.

"Every time you pass the car, you lose about 25% of the berries on the ground, just because of the way the car goes around the bushes," he said. "I think there's going to be a demand for these types of cultivars in the future."

Source: Softer landing for fresh blueberries (Good Fruit Grower)

Potrebbe interessarti anche