Oregon State University undergraduate student Chandler Sprueill in a greenhouse on the OSU campus is helping USDA Agricultural Research Service scientist David Bryla research use of biostimulants in blueberries.

Preliminary findings from research into the use of biostimulants in blueberries are proving positive.

In a study funded by the Oregon Blueberry Commission, David Bryla, a research horticulturalist with the USDA Agricultural Research Service in Corvallis, is evaluating the potential benefits of using different biostimulants in blueberries. At the moment, he is working with seaweed extract and organic (humic and fluvic) acids.

“It is very promising what we are seeing to date,” Bryla said. “So far, both the seaweed extract and organic acids are improving plant growth relative to the well-fertilized control.” And, he said, the best growth appears to be occurring in plants receiving a combination of biostimulants.

Bryla said the plan is to start in the greenhouse and then move to the field, where he will analyze how blueberry plants growing in large pots respond to biostimulants in different soil types over a period of two years.

Use of biostimulants has increased significantly in recent years. The Environmental Protection Agency, which put out a draft guidance for plant regulators earlier this year, describes them as naturally occurring substances and microbes that are used to stimulate plant growth, enhance resistance to plant pests and reduce abiotic stress.

“Their increasing popularity arises from their ability to enhance agriculture productivity by stimulating natural processes in the plant and in soil, using substances and microbes already present in the environment,” the agency wrote in a March 21 release announcing the draft guidance.

“Biostimulants can improve soil health, optimize nutrient use and increase plant growth, vigor, yield and production,” the release states. “They can promote greater water and nutrient use efficiency, but do not provide any nutritionally relevant fertilizer benefit to the plant.”

One theory for the benefit they bring to plants is that they increase nutrient availability, according to Bryla. And, because biostimulants can increase root initiation and growth, some hypothesize they increase water availability for plants, which can be particularly important when irrigation is limited.

Ultimately, Bryla said, he would like to study the molecular aspects of biostimulants to better understand how they work. “We are looking to get a large grant to study the molecular response in the lab very carefully and test each product at different field locations,” he said.

The research, he said, will help uncover optimum rate and application methods for biostimulants.

He added that other crops have shown a response curve when dosed with biostimulants. “You increase growth up to a point with a dosed rate, but eventually you can apply too much and lose production,” Bryla said. “We want to figure out where that point is, so growers know exactly how much to apply.”