Reviewing: In Defense of Plants Episode 427: “Unraveling the Mysteries of Mycorrhizal Networks”

Key Takeaway 1: Researchers have identified that sometimes fungi and plants have a mutualistic relationship, but sometimes it is a neutral or parasitic relationship.

Key Takeaway 2: Mycorrhizal soil amendments won’t always be helpful to gardeners because the nature of this relationship is highly variable and context dependent.

In Defense of Plants is a podcast that explores botany by interviewing experts about their work. I wanted to write about this episode because amending soil with mycorrhizal products is a practice that some gardeners use to boost the health of their plants. However, in listening to this podcast episode, it is clear that doing this might not yield the positive effects gardeners desire.

Who should listen to this podcast?

This episode is worth a listen if you’d like an informative conversation about mycorrhizal networks and soil amendment products. Dr. Matt Candeias, host of the In Defense of Plants podcast, primarily creates content for an audience with a foundational knowledge of botany and ecology. That is to say, it’s often quite technical. However, I have found a number of episodes to be highly accessible to an amateur audience, and this episode falls into that category.

What’s covered in the podcast?

Popular science books like The Hidden Life of Trees convey the forest as a community connected by fungi, but the solely mutualistic relationships described in this book are only partially supported in the scientific literature. In this podcast episode we learn that mutualistic relationships between plants and fungi vary widely based on variables like nutrient availability and environmental context. Often in experiments, a plant’s survival and fitness is related more directly to variables like moisture levels in the soil, proximity to other plants, and root competition with adult trees rather than its relationship to the mycorrhizal network.

The use of mycorrhizal products in horticulture is discussed in the final ten minutes of the episode. Dr. Candeias warns that many products use a single species of fungi to distribute to a global market meaning that it is likely being used outside of its native context. There is little research on non-native fungi and their effects on the environment so it is uncertain what the consequences will be on natural ecosystems. Additionally, the use of these products without the knowledge of when the fungi and plant relationship will be mutualistic is basically just paying a lot of money to hope for the best.

This episode’s guest speaker, Dr. Hoeksema, recommends that you ask a manufacturer three questions if you are going to purchase a mycorrhizal soil amendment product:

• Will the product improve the health of my plants?
• What’s the evidence that the product works?
• What’s the evidence that it’s not going to be a problem for the environment?

I would recommend listening to the podcast if you’d like to learn more about the fascinating world of mycorrhizal research. Not only was the podcast informative on a scientific level but it was also informative on a consumer level.

Where can I find this podcast episode?

Sources

Jason Hoeksema, “Unraveling the Mysteries of Mycorrhizal Networks,” interview by Matt Candeias. In Defense of Plants. Podcast audio. June 25, 2023. https://open.spotify.com/episode/6ahyLrfDB7yAfqkbbGTw7F?si=44674b04f7e44d62