Fungal Inoculation in Pine Seedlings at Louisiana Nursery
At a commercial tree nursery near Evans in western Louisiana, five million loblolly pine seedlings are arranged on twelve expansive circular irrigation tables, each approximately the size of a football field. In September of the previous year, many of these young trees were sprayed with a substance resembling muddy water.
The liquid was actually an extract rich with hundreds of species of wild soil fungi. Brad Ouseman, the nursery manager, expressed confidence that this fungal inoculation would enhance growth yields and reduce reliance on artificial fertilizers.
“By the time January gets here, you’ll tell the difference between that seedling and this seedling,”
Ouseman said, indicating rows of sprayed and non-sprayed pines.
Funga’s Approach: Microbial Treatment Inspired by Medicine
Colin Averill, founder of Funga—the startup supplying the fungal spray—compares the treatment to a medical procedure used to treat certain bowel conditions by transferring gut microbes from healthy donors to patients. Similarly, Funga treats young loblolly pines with wild microbes sourced from soils of thriving pine forests.
“We’re not trying to isolate individual pieces of the soil community; we’re taking the whole thing,”
Averill explained.
“As a result, we get all the complexity and all the interactions that come with it.”
The objective is to cultivate trees that grow rapidly, sequester more carbon dioxide, and require less artificial fertilizer.
The Role of Ectomycorrhizal Fungi in Pine Growth
The Evans nursery supplies seedlings to the extensive network of intensively managed pine plantations spanning over 12 million hectares (30 million acres) across 13 southern US states, an area often referred to as “the woodbasket of the world.”
Loblolly pines, native to the southeastern US, depend entirely on underground fungal partners known as ectomycorrhizal (ECM) fungi. These fungi weave into pine roots to form a “hybrid organ,” as described by Stanford fungal ecologist Kabir Peay, which functions as a trading platform for essential nutrients.
The fungal networks extend into the surrounding soil, scavenging nitrogen, phosphorus, and other nutrients, which they supply to the tree in exchange for energy-rich sugars. Peay emphasized the mutual dependence of pines and ECM fungi:
“We really don’t find one without the other.”
Peay’s research indicates that soil fungal biodiversity is critical for healthy trees and forests. Individual trees may associate with hundreds of fungal species, each accessing different nutrients under varying conditions. In a study, Peay demonstrated that even a two-month delay in seedlings acquiring appropriate fungi can significantly hinder their growth.
Impact of Timber Harvest on Fungal Communities
Across the southern pine belt, clearcut timber harvesting severely depletes the fungal communities essential for young trees. Funga argues that this depletion results in suboptimal growth and increased dependence on artificial fertilizers.
Genomic surveys conducted by Funga suggest approximately 75% of ECM fungal diversity is lost following felling, a figure consistent with studies in loblolly and longleaf pine forests. Recovery of these fungal communities is estimated to take about 30 years, while timber harvesting cycles range from 15 to 25 years, implying some pines may never benefit from fully mature ECM networks.
Rachel Cook, forestry professor at North Carolina State University, cautions that the timescale for ECM fungal recovery remains uncertain. While agreeing that significant disruption occurs, she suspects warmer southern soils may accelerate recovery compared to Funga’s estimates.
Funga’s Methodology for Enhancing ECM Communities
Despite uncertainties, Funga maintains that exposing trees to the most productive ECM fungi from the outset benefits growth. The company surveys forest soils across the southeastern US to identify thriving fungal communities, which are then used as inoculants in small-scale trials. Promising communities are cultured using natural organic matter as substrate, effectively creating in-forest compost heaps. Extracts from these cultures are applied at scale in industrial nurseries.
Founded in 2022, Funga inoculated approximately 500 acres in its first year. By 2025, this expanded to about 25,000 acres. Averill estimates that his startup treated one in every 40 loblolly pines planted in the southeastern pine belt in the previous year.
Early Results and Expert Perspectives
Initial outcomes are encouraging. Averill reported growth responses exceeding 100% in some locations, with an overall target of a 30% growth increase on average.
“We’ve seen growth responses in excess of 100% in some locations,”
he said.
“Overall we target 30% [growth boost] on average. We believe we’re about to achieve that.”
Rachel Cook, co-director of the international academic-industry Forest Productivity Cooperative, noted that a 30% growth increase from fertilization is typical, suggesting Funga’s biological treatment may rival gains currently achieved through costly chemical inputs, aligning with the company’s goals.
“I really think this could be a next big step in managing forests in the south-east,”
Cook said.
“I am optimistic, but I’m cautiously optimistic, because we need more data.”
Soil Nutrient Deficiencies and Forestry Practices
Many soils beneath southern pine plantations are deficient in key nutrients, partly due to decades of intensive tobacco and cotton farming prior to the establishment of commercial forestry in the 1930s. Although nearly a century of continuous forest cover has improved soil conditions, nutrient shortfalls remain.
Despite the orderly rows of pine trees resembling agricultural fields, Cook emphasized that forestry practices are far less intensive. Pine stands receive fertilization at most three times over 25 years, with soil disturbance occurring only at harvest.
“Our ‘intensive’ is minuscule compared to agriculture,”
she stated.
Potential to Replace Chemical Fertilizers
Averill hopes fungal inoculation will eventually eliminate the need for chemical fertilization, offering a low-cost, self-sustaining alternative to fossil fuel-dependent inputs, whose prices have risen sharply in recent years.
Previously engaged in academic research, Averill demonstrated that soil fungal community composition predicts tree growth and carbon sequestration as strongly as rainfall, a finding with significant implications.
He founded Funga in 2022, anticipating that emerging environmental markets, including carbon markets, could provide financial incentives to translate research into practical solutions addressing climate and biodiversity challenges. In 2023, Funga secured its first major commercial contract: an 11-year, multimillion-dollar carbon removal agreement with the streaming company Netflix.
Challenges and Integrity in Carbon Markets
Carbon markets face scrutiny due to concerns about effectiveness. A comprehensive 2022 review concluded that many offset schemes have suffered from integrity issues and failed to deliver genuine emissions reductions, although it acknowledged the existence of high-quality projects. Common problems include non-additionality—crediting projects that would have occurred regardless—and impermanence, where carbon stored in trees is later released by fire or decomposition of short-lived forest products.
Averill recognizes these challenges.
“Greenwashing is absolutely real,”
he said, but argued that Funga’s model addresses these weaknesses by basing credits solely on additional tree growth relative to untreated control plots. Furthermore, contracts require landowners to grow trees to saw-log size before harvest, directing timber towards lumber and construction, which are more durable carbon stores compared to pulp or biomass.
Funding Model and Future Prospects
Because Funga’s treatments are financed through carbon revenue, landowners incur no upfront costs. However, fungal inoculation must ultimately demonstrate cost-effectiveness compared to fertilizers and other interventions for land managers operating under budget constraints.
Funga’s ambitions extend beyond southern pines. Averill indicated that the company’s next major focus is Douglas fir in the Pacific Northwest. He is also involved in field trials inoculating broadleaf trees and Sitka spruce.
Scientific Significance and Potential Breakthroughs
Regardless of whether fungal inoculants revolutionize southern pine forestry, Peay believes the broader scientific endeavor—understanding the ecology of organisms that remain largely uncharacterized—is the true prize.
“If Funga can identify optimal fungal communities and transfer them efficiently on to receptive young trees, that would be a really big breakthrough,”
he said.
