Most Common Fungus In Marijuana Plants

common fungus

Fungi often appear in moist environments. Anyone who wants to grow cannabis should know the most common fungus in marijuana plants. Cannabis plants are especially susceptible to these organisms. It is because they have a dense canopy and leaves that provide an ideal environment for mold growth. We will discuss some of the most common fungi that can hurt your cannabis plants and how you can make sure you do not get any unwelcome guests.

Common fungal that can hurt your marijuana plants are Botrytis cinerea, Powdery Mildew, Aspergillus, Rhizoctonia Solani, Fusarium, and Sclerotinia Sclerotiorum. These fungi are most likely to infect your marijuana plants. Having high humidity or temperature in the grow room or other factors can result in fungus. Therefore, it is essential to maintain excellent air circulation in the cannabis grow room to avoid these problems.


Botrytis Cinerea / Root Rot in Cannabis

Botrytis is one of the most common fungi that hurt marijuana plants. This fungus is most likely to occur in the later stages of growth, such as the flowering stage. If you see a grey, fluffy mold at any part of the stem and leaves (especially if they come from an older leaf), this could be Botrytis Cinerea or Root Rot. It most commonly hurts stems and buds, but it can also affect the leaves. This fungus most commonly occurs in high humidity. It could also happen if you have had stagnant water around your marijuana plant for too long without proper drainage. If this happens, be sure to flush out all infected areas with clean water and keep them well-ventilated so that they are not damp for an extended period.


Powdery Mildew in Cannabis

Powdery Mildew is another most common fungi that can hurt your marijuana plant. This fungal infection will cause a white powder to form on the surface of leaves, stems, and buds. It most commonly occurs when the temperature or humidity is high, or the wind pushes the spores to the leaves. This fungus can stunt the growth of your marijuana plants and reduce their yield. It most commonly hurts older leaves and especially if they become dehydrated. To avoid powdery Mildew, keep the humidity below 50% and make sure to provide plenty of ventilation for your marijuana plants through all stages of growth.


Aspergillus in Cannabis

Aspergillus, another most common fungi that can hurt your marijuana plant, is most likely to occur when high temperatures and humidity levels are low. This fungus hurts the roots of cannabis plants and the soil. It causes them to turn black, which will reduce the nutrient uptake in the rest of the plant. The most common symptom of this fungal infection is yellowing leaves with brown spots at the edges. To avoid Aspergillosis, ensure good drainage for your marijuana plants and keep them well-ventilated during growth. In addition, ensure that you are not overwatering or overfeeding your plants with nutrients. It can create an environment that is too moist, which encourages mold growth on the roots of your cannabis plant.


Fusarium Oxysporum in Cannabis

Fusaruim Oxysporum is another common fungus that can hurt your marijuana plant. It is most likely to occur when there has been a long time with wet conditions and high temperatures. This fungus most commonly causes wilting leaves, turning brown or yellow during vegetative growth. It most commonly occurs in the soil if you have had standing water for too long without proper drainage because this fungus thrives in moist environments that do not drain well. If you notice symptoms of Fusarium Oxysporum, be sure to provide good drainage in your grow room and reduce the amount of water you are providing during vegetative growth.


Rhizoctonia Solani in Cannabis

Last but not least, Rhizoctonia Solani, another common fungus that can hurt your marijuana plant. It is most commonly occurs in the plant’s stem at the soil line if there has been a long time with wet conditions and temperatures are high. It can easily also be blown around on dust particles and spread around in the air. It can cause small brown spots to develop on cannabis leaves, eventually enlarging and covering a greyish-brown mold during vegetative growth. It often occurs when the temperature is high and low humidity levels. However, it can also happen if your marijuana plants are getting water too frequently. It can also happen if you have wet conditions in the grow room for an extended period without proper drainage. To avoid Rhizoctonia Solani, ensure proper drainage in your cannabis grow room and reduce the amount of water you provide during vegetative growth.


How To Prevent Fungus In Marijuana Plants Indoors

You can do a few things to help prevent fungus infections in marijuana plants when growing indoors. Making sure that your grow room has proper drainage and is well-ventilated. This will help reduce the amount of moisture in the air, discouraging mold growth. You should also make sure not to overwater or overfeed your plants with nutrients because this can create an environment that is too moist, encouraging mold growth. It would help if you also avoided watering or misting the leaves of your plants directly because this can spread fungal spores around the plant and cause problems in most parts of it.

Getting an air and surface purification system is an effective way to prevent and reduce pathogens that will help provide clean air to grow high-quality marijuana. AirROS is a commercial air, and surface purification system that utilizes and creates ROS (Reactive Oxygen Species) that destroys pathogens, mold, viruses, yeast, bacteria and reduces cross-contamination, plus provides odor control.

UV for Cannabis

How Does AirROS Air & Surface Purifier work?

First, it kills pathogens and odor as it passes through the air purifier. Then, it sanitizes the air that comes out of the purifier, enters the environment, and continues to sanitize all surfaces it contacts. Here is the 2 stage process:


Phase 1- Primary Air Cleaning

Placed within your room’s airflow, air from the environment containing microorganisms enters the purifier’s internal chamber. The reaction chamber creates non-thermal plasma and generates ROS. ROS has comprised of 5 short-lived, highly Reactive Oxygen Species:

  • Atomic oxygen,
  • Singlet oxygen,
  • Hydroxyl radical,
  • Superoxide 
  • Peroxynitrite

These break down carbon-to-carbon bonds that sanitize the air and destroy all bacteria, molds, viruses, and other pathogens as they pass through the reaction chamber.
Phase 2- Secondary Surface & Air Cleaning
Provides Surface sanitation and continued Air sanitation. The purified air now diffused into the environment contains longer lived Reactive Oxygen Species:

  • Gas-phased H2O2- hydrogen peroxide
  • Low concentration levels of O3-ozone

That further sanitizes room air and surfaces. In addition to treating the ambient air as it passes through the reaction chamber, using the H2O2 and O3 diffused into the environment. AirROS units will further sanitize all Surfaces and control Odor, resulting in clean air and surfaces 24/7.

Fungal spores are everywhere. Most common fungus in marijuana plants exist in the air and on surfaces! It should come as no surprise that they can be a problem for growing indoor cannabis. Especially, those who care about their plants’ health and want to produce a high-quality product without risking mold or other problems from these fungi. We have discussed some common fungal types found in grow rooms and identified them. Also, what symptoms they might cause and how you can prevent them from occurring by using AirROS’ air and surface powerful purification system designed specifically for commercial cultivation spaces. If you’re a cultivator looking for more information on how to keep your space fungus-free, schedule a call with us or submit a form here.


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