The Best Bacterial and Fungal Controls for Marijuana

The Best Bacterial and Fungal Controls for Marijuana
May 15, 2020

Your precious cannabis plants live under constant threat from disease, molds, pests and pathogens. If you’re a novice cannabis grower, you’ll need to learn to anticipate and prevent problems, rather than dealing with them as they arise. Be proactive, not reactive… as they say. That said, even the cleanest and most well-organized of cannabis gardens can face issues. This editorial will explore the best bacterial and fungal solutions for your grow, measures that can help cure and restore your beautiful marijuana plants.

Natural, organic remedies for fungus and bacteria are ALWAYS the better option. While chemical-based fungicides and bactericides do work quickly, they can have dire consequences for the environment, and, ultimately, to human health.

One of the best approaches is to use products containing beneficial organisms. These products are either used stand-alone or included in IPM strategies.

Ampelomyces Quisqualis

AQ-10 is a bio-fungicide based on Ampelomyces quisqualis – isolated initially from Oidium sp. It’s usually sold in water-dispersible granule form. This hyperparasitic fungus infects white powdery mildew, forming fruiting bodies within the hyphae, conidiophores and cleistothecia. This parasitism not only slows down the growth but kills the entire colony, eventually.

Bacillus Pumilus

The spore-bearing Bacillus pumilus is commonly found in soil. It has proven to be highly beneficial, inhibiting soil-borne pathogenic fungi – Rhizoctonia solani and Fusarium spores – from germinating in the root zone. If needed, it is also available as a white powdery mildew fungicide under the “Sonata” brand name.

Bacillus subtilis

This naturally occurring anti-fungal bacterium is typically found in vegetation and soil. It’s used to treat seeds as the beneficial bacteria can stay alive for prolonged periods. Plus, it multiplies even after the seeds germinate and provides protection throughout the entire life-cycle of the plant. As a robust bio-control agent, it combats blight, gray mold and various strains of mildew, but doesn’t negatively affect the environment or humans. For this reason, it’s perfect for organic farming.

Bacillus Subtilis is offered under several brand names. Marijuana growers can choose between its two strains – the foliar variant (QST 713), which best used against powdery mildew, or the soil and seed treatment (GB03 or MBI600) to control root zone contamination.


The soil-dwelling parasitic fungus, Gliocladium, produces an enzyme toxic to bacteria and other fungi. It inhabits the same place as the pathogens, causing them to deteriorate. Use this in your marijuana operation to control gray mold and suppress the spore production. You can purchase it under various commercial brands such as Glio-mix, SoilGard, Primastop, and Prestop. Once you have a Gliocladium product, apply it as a soil drench.


By acting as a good bacteria, milk aids the human body in boosting the immune system and warding off infection. Its use in plants, marijuana included, offers the same benefit. The nutrient-rich liquid food is a natural germicide and an effective treatment for powdery mildew.

Spraying one part milk to nine parts water every week helps prevent the appearance of powdery mildew. It also helps with existing infections. The disinfectant properties of milk can also sterilize your gardening tools, making it an excellent alternative to bleach.

Recipes mostly employ whole or skimmed milk. Garlic and cinnamon can be added to the mix as well. One more tip: when rinsing empty milk bottles, pour the diluted milk on your weed instead of letting it go down the drain. This way, you get to protect your plants while also avoiding wastage.


Pseudomonas is a genus of bacteria that live and reproduce in water, soil and damp areas. In the 1980s, its anti-pathogenic applications became widely utilized in horticulture. It’s applied as a soil drench, foliar spray, seed soak or seedling rooting treatment.

This bio-control agent increases plant disease resistance and promotes growth by inhibiting harmful micro-organisms. Additionally, it doesn’t leave toxic residues and nor destroys beneficial organisms, making it an environmentally friendly option. Use this material for chlorosis, bacterial blights and necrosis, as well as soil pollution. Several brands carry pseudomonas, so refer to the packaging for directions.

Streptomyces Griseoviridis

This beneficial bacterium is a potent fungicidal agent. Use it to prevent or control gray mold, pythium, root rot, stem rot, fusarium wilt and other fungal diseases. It’s available under commercial brands like Mycostop, which you can purchase from local gardening supply shops.


This beneficial fungus is an effective biological control for plant fungal diseases. It’s present in almost types of soil and is parasitic in nature, feeding on other fungi that dwell on the root system. This activity promotes healthy root growth, resulting in optimal nutrient uptake. It can also deter fungal growth on the actual foliage.

There are several species of Trichoderma, but harzianum and viride are the most typically used as biocontrols in marijuana grow operations.

T. harzianum is used as a seed treatment, soil treatment and foliar spray to suppress fungal pathogens such as Botrytis and Fusarium. Viride, on the other hand, provides excellent protection against Armillaria, Pythium and Rhizoctonia. You can also use it as a seed dressing for soil-borne infections like Fusarium wilt, Macrophomina phaseolina (charcoal rot) and Rhizoctonia solani (root rot).

Bacterial and Fungal Control Agents

Several organisms can be used as prevention and control of marijuana plant diseases. Compared to chemicals, the use of bacterial and fungal control agents is slower, but preserving the soil ecosystem should be the number one priority of ALL cannabis growers.

Kyle Kushman, for example, focuses deeply on the synergy between plants and beneficial organisms. As the father of indoor veganic cultivation, his mission is to always maintain a healthy, diverse microbial ecosystem in his garden. As a result, he grows the highest quality buds with peak potency, fragrance and flavor… and free from contamination, too.

Beneficial bacteria and fungi are essential to his repertoire of disease control measures. They could be yours too.