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Tree nut growers who want to know more about biostimulant products and using them in orchards as part of their nutrition management plans will have the chance to learn more about their uses and effects on crops at the Biostimulant World Congress being held in Sacramento.
The 9th Biostimulant World Congress will take place Nov. 30 to Dec. 3 at the SAFE Credit Union Convention Center. This will be the largest global event featuring biostimulant use in agriculture. This is the first time the Congress has been held in California. Previous events were held in European countries or in Florida.
“This is a powerful way of sharing information about biostimulants with the scientific and commercial communities,” said Patrick H. Brown, UC Davis plant scientist and chair of the Congress. He said about half of the expected 1,200 to 1,600 attendees will be from the scientific and farming communities and half will be from commercial entities. Researchers, agronomists, crop advisers and fertilizer company representatives are expected to attend.
The four-day event will feature both scientific and commercial tracks, balancing the latest research in plant biology with market trends, regulations and evidence-based field applications.
Why Biostimulants Matter
Brown, who also spoke about biostimulant use in agriculture at the recent 2026 Salinas Biological Summit, noted that biostimulants represent one of the fastest-growing segments in crop production.
“We have learned that climate variability can have a great impact on crop productivity,” Brown said. “Biostimulants are a tool to mitigate that variability.”
“Agriculture does not have anything else in the toolkit to mitigate some of the effects of that climate variability.”
He said a potential 3,000-pound almond crop could be reduced to 2,000 pounds by an unexpected weather event during bloom, the growing season or at harvest.
“This is something that can’t be overcome by applying more fertilizer or water,” Brown said.
He first became involved in biostimulant research at the request of several large international fertilizer companies. Brown said he attended the first congress in 2012, held in Rome, Italy, to learn more about these new products and their relationship with plant health.
The goal, he said, is commercialization of biostimulant products. Presently, he estimated that less than 30% of growers and crop consultants are knowledgeable about biostimulants and mainly use seaweed and humic acid products as part of their nutrient management plans. Other growers, Brown added, are using biostimulants on an experimental basis in their orchards.
Agriculture does not have anything else in the toolkit to mitigate some of the effects of that climate variability.
— Patrick H. Brown, UC Davis plant scientist and Biostimulant World Congress chair
Improving Nutrient Efficiency
Renee Pinel, president and CEO of the Western Plant Health Association, confirmed a rapidly growing interest in the use of biostimulants in agriculture.
“They are not replacing fertilizers, but they help plants better utilize the nutrients applied to the soil or in the irrigation,” she said.
Pinel explained that using biostimulants helps with nutrient uptake. When plants can use the applied nutrients more efficiently, it helps growers stay within their target application and not overapply nutrients.
“If your recommendation is for 200 pounds of N per acre, and you are applying a biostimulant, you’re not going to add another 50 pounds of N just to be safe,” she said. “Growers can feel more confident with their fertilizer applications.”
Long term, Pinel added, biostimulants can help with sustainability. Biostimulants take a broad approach, focusing on plant health, improving stress tolerance and enhancing a plant’s response to environmental conditions like drought or extreme temperatures.
Growers can compare how their trees look prior to and after the biostimulant application. Short term, biostimulants can be applied to help plants overcome environmental stressors during bloom, during crop development or at harvest.
Where biostimulants appear to help most, she said, is in driving young root growth. There can be challenges with biostimulants, she cautioned, with varying effects due to the age of trees, soil and irrigation methods.
Determining return on investment with biostimulant use is not easy. Pinel said there are not many complete studies. From a regulatory perspective, they can be helpful in augmenting fertilizer usage.
What Are Biostimulants?
The EPA defines plant biostimulants as “products containing naturally occurring substances, microorganisms or their synthetic equivalents that, when applied to plants or the rhizosphere, stimulate natural processes to enhance nutrient uptake, nutrient use efficiency, tolerance to abiotic stress or crop quality and yield.”
The statement notes that while biostimulants can influence plant vigor and yield, they do not manage pests or protect against diseases. Categories of biostimulants include protein hydrolysates, humic or fulvic acids, seaweed extracts and botanicals, chitosan and other biopolymers, and inorganic compounds.
Protein hydrolysates are amino acid-based and are associated with protein hydrolysis from crop residue and manure. Humic and fulvic acids are products from organic soil matter breaking down. Like protein hydrolysates, they enhance nutrient availability and improve soil structure.
Seaweed extracts and botanicals have been used in agriculture for centuries but only recently studied for their biostimulant properties. When applied to soil, seaweed can help with water retention and support overall soil health.
Chitosan is a plant biostimulant that is extracted from the biopolymer chitin, which is a fibrous substance used in the cell walls of fungi. Chitosan has been used to increase plants’ ability to withstand abiotic stressors like extreme temperatures.
Inorganic compounds include silica, selenium, cobalt, sodium and aluminum. They can strengthen cell walls and promote growth.
Biostimulants are applied in three primary ways: as seed treatments before planting, as soil applications directly to the root zone or as foliar sprays applied to plant leaves. The method depends on the crop’s growth stage and the specific type of biostimulant being used.
Applications are typically tied to growth stages or environmental triggers to improve stress tolerance.
Information about the Biostimulant World Congress can be found at https://informaconnect.com/biostimulants-world-congress.
Publisher’s Take
The Big Picture: What to do Next
1. Biostimulants help crops manage environmental stress
Researchers say these products can improve a plant’s ability to tolerate drought, temperature extremes and other climate-related challenges.
2. They complement fertilizer programs
Biostimulants don’t replace fertilizers but can help plants use applied nutrients more efficiently.
3. Root development shows the greatest promise
Improved young root growth appears to be one of the most consistent benefits, although results vary by orchard conditions.
4. Grower adoption is still evolving
Many growers are testing biostimulants, while research continues to evaluate their performance and return on investment.
5. Sacramento will host the global conference
The Biostimulant World Congress comes to California for the first time Nov. 30-Dec. 3, bringing together researchers, advisers and industry leaders.
Cecilia Parsons | Associate Editor
Cecilia Parsons has lived in the Central Valley community of Ducor since 1976, covering agriculture for numerous agricultural publications over the years. She has found and nurtured many wonderful and helpful contacts in the ag community, including the UCCE advisors, allowing for news coverage that focuses on the basics of food production.
She is always on the search for new ag topics that can help growers and processors in the San Joaquin Valley improve their bottom line.
In her free time, Cecilia rides her horse, Holly in ranch versatility shows and raises registered Shetland sheep which she exhibits at county and state fairs during the summer.