Trichoderma, The Fungal Antihero in Cannabis Propagation
When a cultivator hears the word “fungus,” it’s usually uttered along with unfortunate and expensive news. Although seasoned growers understand the importance of biodiversity within their plant’s root zone, it’s rarely good news when fungi are spotted among your crop.
That being said, not all fungi should be bounced from the propagation party. Living soil and seed-starting mediums can contain a wide range of beneficial organisms, including Trichoderma spp. (species pluralis, or multiple species). In fact, Trichoderma’s primordial ancestors may very well be some of the plant kingdom’s most valued allies in the fight for growth and survival.
Whether you propagate cannabis in starter plugs or soil, many species of Trichoderma continue to honor the ancient alliances between the Fungi and Plantae Kingdoms. Let’s talk about why this is a significant benefit to cannabis growers regardless of growing medium or propagation technique.
Supporting Microbial Allies at the Root Zone
Many starter and rooting cubes strategically include peat as a component. In addition to peat’s inherent benefits, this organic, spongy material contributes to ideal conditions for Trichoderma to thrive (a microorganism within the fungi family). Propagation plug manufacturers and horticulture engineers understand the botanical benefits of this fungus’s many plant-friendly species.
It’s true that there are fungi that are highly destructive to cannabis cultivators, such as powdery mildew (an issue scientists are working on). But don’t let the “F-word” scare you; there is significant scientific backing to support recruiting this symbiotic fungus to partner in root development.
The presence of Trichoderma in your rooting medium and soil often affords many advantages. Even so, always conduct your own research, and always consult your master grower before introducing any changes to your operation’s growing media, nutrient mix, or lighting protocols.
5 Reasons to Embrace Trichoderma in Your Grow
Introducing and maintaining a microbially balanced ecosystem within your growing medium isn’t a new concept among growers. However, what might be surprising to “green” cultivators is that fungi comprise a role in the microorganism ensemble performing in your living soil and starter plugs.
Let’s explore five benefits the fungus, Trichoderma, brings to your rhizosphere.
1. Promotes Root Elongation
Trichoderma produces hormones that are naturally occurring in its rooting counterpart, particularly indole-3-acetic acid (IAA), a type of hormone that stimulates root cell elongation and branching (among other developmental processes). It also reduces ethylene levels via ACC deaminase activity, reducing stress-induced levels of ethylene that otherwise inhibit root growth.
2. Increases Nutrient Uptake
By enhancing the root’s surface area, Trichoderma increases the plant’s capacity to absorb nutrients. Just as important, it releases organic acids and siderophores (a signature molecule synthesized by bacteria and fungi) that chemically bind to minerals like iron and zinc.
Fungi such as Trichoderma create these compounds to increase the bioavailability of iron. While this process is performed to benefit the fungus, excreting siderophores also results in a serendipitous benefit to the cannabis plant’s rhizosphere (because chemistry)!
3. Suppresses or Eliminates Pathogens
Trichoderma combats pathogens through mycoparasitism. Simply speaking, Trichoderma will identify another (and usually harmful) species of fungi within the root zone and attack it for its resources. The aggressor—Trichoderma—besieges the defending fungus, releasing hydrolytic enzymes to tear down its walls (literally), kills it, and claims the nutrients as spoils of war.
It also outcompetes pathogens for space and nutrients in the rhizosphere and produces antimicrobial secondary metabolites. In the microorganismal conflict for dominance in your plant’s root zone, Trichoderma often carries the bigger stick.
It’s easy to see why this specific fungus is leveraged as an organic fungicide and disease deterrent. When existing in harmony within the rhizosphere, it can reduce the amount of chemicals used to prevent disease while helping provide developmental support.
4. Assists in Seed Germination
Trichoderma-treated seeds often germinate faster and more uniformly. This is due to a combination of hormonal signaling and early colonization that stimulates initial root vigor.
Seedlings are also very susceptible to damping-off diseases (such as root rot). If you’re using a growing medium containing beneficial strains of Trichoderma (as we discussed directly above), then you can imagine what happens to the disease-instigating organisms that attempt to infiltrate your seedling’s or cutting’s root zone during propagation. Spoiler: it doesn’t end well for the pathogens.
5. Initiates a Botanical “Vaccine” Response
Cannabis cultivators have been conditioned to be on high alert when it comes to identifying and mitigating parasitic, unwanted species of fungi. These include mold and powdery mildew. An infection from an invasive species of fungi or bacteria can quickly render a crop unsalvageable unless remediation is quickly implemented.
Trichoderma is an exception to harmful pathogens, falling under the category of Plant Growth-Promoting Fungi (PGPF). In addition to the impressive list of benefits above, this mycelium triggers the “host” plant’s defense response, including the activation of genes responsible for helping the plant ward off dangerous microbes.
When the cannabis plant detects the colonization of Trichoderma in the root zone, it begins preparing for an impending attack. Little does the cannabis seedling or cutting know, the friendly fungus is more interested in pursuing other fungi and pathogens that pose a real threat. The plant activates its defense and immune responses systemwide. Although these countermeasures are not needed to control the Trichoderma presence, those same defenses prove quite effective against present and future organisms that intend to do the plant harm.
As demonstrated above, Trichoderma’s presence essentially primes what is characterized as a “vaccine response” in the plant’s immune system.
Microbial Allies, Not Microbial Overlords
While Trichoderma is widely regarded as a beneficial genus of fungi, there are occasional reports of negative effects—particularly when species and strains are improperly matched to your plant species. Overcolonization in sterile substrates can, in rare cases, compete with young seedlings for limited resources, potentially stunting early growth.
It’s important to position Trichoderma in your botanical vanguard, but don’t let it become the general calling the shots.
To mitigate the risks of a fungal coup or mutiny, cultivators should select well-characterized commercial strains of Trichoderma, use reputable, science-based starter plug manufacturers, and perform their due diligence to monitor for and maintain balanced microbial diversity in their plant’s root zone.
Taking the precautions above, along with leveraging your master grower’s experience and knowledge, can level up your cannabis cultivation business by giving your plants the best start from day one.
