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How to Prevent Bud Rot – The Ultimate Guide for Cannabis Growers

Bud rot, aka gray mold, is an extremely common problem in cannabis cultivation. It’s triggered when there’s excess moisture in the air and can easily destroy entire crop cycles.

As cannabis plants are highly regulated, growers can’t use traditional fungicides. The only fully organic, GMP approved method to prevent bud rot, is to maintain low humidity, using dehumidification.

Bud rot prevention is arguably the biggest issue in cannabis cultivation. Bud rot (botrytis cinerea) is an incredibly wide-spread disease, affecting a wide range of crops, including cannabis. It’s a type of mold, similar to powdery mildew and downy mildew.

One of the biggest problems, when it comes to preventing gray mold, is that mold spores are omnipresent. They travel through the air and can be found almost anywhere in the world. It can infect a greenhouse or indoor grow, just as easily as it affects outdoor plants. So indoor and outdoor growers all suffer from bud rot.


How to Detect Bud Rot – Gray Mold Symptoms

Bud rot develops in cannabis when botrytis cinerea, a type of fungus, infiltrates the plant. The fungus then develops inside the plant, before symptoms become visible.

Early signs of bud rot eventually start showing on and around infected buds in the form of darkening and softening of the plant surface. After the initial symptoms, botrytis will burst out in gray fuzzy mold.

Despite commonly infecting cannabis buds, symptoms can appear anywhere – on plant leaves, stems, flowers, or the anywhere on the rest of the plant.

The fuzzy gray mold that develops on the plant is, in fact, millions of fungal spores. So once the mold is visible, botrytis spores are ready to travel and infect nearby plants. At this point, it’s much more difficult to stop the spread and prevent a larger outbreak.

In all plants, including cannabis, botrytis will cause shriveling, rotting and eventually death.


Bud Rot Is a Humidity Problem

Botrytis, or bud rot, requires specific conditions. More specifically, it requires water in order to develop and start creating spores.

So, the most common cause of bud rot is high humidity.

When humidity is too high, and relative humidity reaches 100% (the dew point), water starts to condense on different surfaces. These include structural elements, equipment, and most importantly – on the plants themselves.

Cannabis buds are especially dense. So moisture can easily become trapped, leading to condensation occurring inside the buds themselves, creating the perfect conditions for gray mold to develop.

Needless to say, this makes cannabis especially susceptible to bud rot during the flowering stage.


Bud Rot Prevention – How to Prevent Mold in Cannabis

According to IPM (integrated pest management), prevention is always more beneficial than post-outbreak treatment.

Using a combination of the following techniques can help prevent bud rot, by decreasing its presence and ability to develop.


Prevent Molds Using Dehumidification

High humidity is the leading cause of bud rot. So, it’s no surprise that the most effective way to prevent bud rot is dehumidification.

Using dehumidifiers, such as DryGair, lets growers remove excess moisture from the air, in a highly energetically efficient way.

DryGair uses a controlled condensation technique to remove water vapor at a rate of ~45 liters per hour. This ensures dry conditions in the greenhouse or grow room, despite constant plant transpiration.

Keeping relative humidity at low levels reduces the risk of dew point condensation, making it almost impossible. In an environment with no condensation and zero water presence, bud rot can be completely prevented.


Improve Climate Conditions with Air Circulation

A common problem in cannabis cultivation is the development of microclimates. These are small, local pockets of humid air. So, despite dehumidification, some plants may still experience humid conditions, allowing bud rot to develop.

The most effective way to combat humid microclimates is by utilizing air circulation. Air circulation is unique airflow method, in which air is circulated 360°, creating homogenous conditions throughout the space.

DryGair dehumidifiers come equipped with a patented air circulation mechanism for this exact purpose. All DG dehumidifiers ensure low humidity and uniform climate conditions, making them the perfect bud rot prevention tool.


Maintain Healthy Plants

It may seem counterintuitive to include healthy plants as a bud rot prevention method. But plant health can make a great difference and help you avoid bud rot all together.

Botrytis often infiltrates plants through wounds. So making sure your plants are uninjured can help prevent bud rot infections in the first place.

Additionally, there’s a short period between the appearance of symptoms and full-blown spore development. So growers may be able to prevent the spread of bud rot by simply removing plants with suspected infections.


Additional Preventative Measures for Bud Rot

Preventing bud rot by controlling greenhouse or grow room climate conditions is without a doubt the most effective option.

However, there are several other measures growers can use to help prevent bud rot or its symptoms.

The most common of which is neem oil. This oil, extracted from the Neem tree, native to India, contains natural fungicidal materials. So, to a certain degree, growers can use it to prevent bud rot.

For more information on bud rot prevention, please feel free to contact us!

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