Identifying and Removing Bud Rot
Bud rot is a dreaded sight for any grower.
The first symptom is usually the sugar leaves turning yellow or starting to curl and twist. Discolouration can occur overnight and usually shows near the base of leaves.
Mold and bud rot on cannabis plants is normally caused by lack of airflow or humid conditions, but it can also be caused by bugs or infected clones which cause plants harm.
They can cause crops to sicken and even die though there are preventative steps growers can take, such as adjusting humidity levels, adding more airflow, and immediately removing any infected buds.
In this Sticky Seeds guide, we review how mold and bud rot is identified, treated, and removed from a cannabis plant without posing more harm to crops.
Bud rot or mold is the last sight growers in the garden want to see. These fungal pathogens develop at the heart of cannabis buds and can be difficult to spot when first forming on plants.
Mold is something all gardeners should be aware of as spores can appear nearly anywhere. Since mold can strike at any time it is imperative growers take preventative measures to keep it and bud rot away. Many mold types infect plants through powdery mildew and bud rot, also known as botrytis cinerea, which is the most common. Left unchecked, these diseases can wreak havoc on crops, the ability to detect early signs of it is essential to ensure healthy plants.
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What is Bud Rot on Cannabis Plants?
Bud rot is a mold that develops in the dense cores of cannabis buds.
The infection begins at the stem, inside the bud, and slowly travels outwards, which makes it hard for growers to detect it early on before damage occurs. Following its onset, bud rot breaks down surrounding buds and then spreads in all directions. Soon after, it produces spores and travels to other areas of the plant or garden.
At first, rotting appears white and whispy though turns grey or black as buds become mushy. Moldy buds are not safe to consume and should be pruned, bagged, and removed from the garden and grow space.
It is common practice for growers to remove only infected areas so the rest of the plant can grow.
However, if the infection is uncontrollable or widespread, entire plants, and not just its infected parts, may need to be removed from the garden entirely in order to protect the rest of the harvest.
Mold usually forms outdoors after rainfall or at the end of seasons when buds become large and dense.
Consumers should watch for mold in the cured product when breaking buds apart. If present, mold will be easily seen inside the bud and should be discarded and not consumed. Mold has an aroma and smells wet, musty, and old and leaves a sour aftertaste if smoked, if something tastes or smells off, inspect it.
What does Bud Rot look like
Mold is a fungal pathogen usually developing in buds during later stages of flower development. At first, no signs or symptoms appear as it remains dormant while infecting the plant.
However, once in an environment optimal to its growth, mold rapidly spreads, rots buds from the inside out, and crumbles surrounding layers while spreading in all directions.
Denser buds are usually impacted most, though in some cases, patches may be visible across the entire plant. As mold spreads it produces and transmits spores to surrounding plants and can be an issue even once plants are harvested and drying.
How do you detect bud rot is a common question among newcomer growers though there are several giveaways indicating its onset in the garden.
The first sign of bud rot is the discolouration of flowers and the sugar leaves that protrude from them. Buds will show pockets of grey, black, brown, or purple chunks that look dry and brittle.
It initially appears as a pale-powdery mildew though becomes darker once buds assume a slimy texture. Once mold takes over, infected buds detach from plants to show dusty interiors of mold spores caused by the pathogen.
Colas are central flower clusters forming atop main stems and are often where the onset of bud rot starts.
Colas appearing dry or dark may indicate the presence of mold. Diseased colas stand out in contrast to healthy plant tissue making it easy for even newcomer growers to tell something is amiss with the plant.
At times, growers may see yellow leaves sprouting from colas which may seem to happen overnight.
The sudden emergence of yellow leaves from colas may be a sign of mold at the base of leaves. If yellow leaves begin to show then the grower should try giving them a slight tug, if they slide straight out then they should begin a close inspection of the bud as bud rot is likely to be present.
How to Prevent Mold and Bud Rot on Cannabis Plants
To prevent it, we must understand it. Here is what causes bud rot:
- High humidity
- Poor ventilation – This is only an indoor growers problem. Plants perspire water into the air which causes a lot of humidity when not dealt with. Adequate extraction is crucial for cannabis plants.
- Lack of air flow – Even if you grow space is under high extractor, bud rot can still attack. Often growers place plants too close together, causing a lack of airflow in between the branches. If the bottom of the plants is not pruned then the leaves will block airflow under the plants. It is good practice to remove 20% of the bottom plant to give a boost of the airflow underneath.
- Prune 20% from the bottom of plants to create airflow underneath.
- Space plants apart properly.
- Water plants appropriately (This avoids water being sat underneath this plants which is slowly evaporate and cause more humidity).
- Train plants to create more main colas by using low-stress training. Instead of one extra large bud, the plant will create multiple heads that are slightly smaller and less
likely to rot. This is also a great way to increase yield. - Checking colas for rot while harvesting, if mold is found the infected plant material should be discarded and the rest preserved.
- Harvesting after dry spells, if cultivating outdoors, as it is best to harvest plants when no rain has fallen for a few days as this means buds will have low moisture contents.
- Wet trimming plants by removing fan leaves before drying as this reduces moisture in the drying room whilst increasing airflow for helping dry buds too.
- Leaving space between branches that are hanging to dry. One technique is to use dehumidifiers to remove moisture in the air.
- Creating optimal drying environments, dark spaces with a temperature of sixty to seventy-five degrees Fahrenheit, and relative humidity of around 40 to 45 percent is ideal.
- Adjusting dry speeds. If bud rot whilst drying cannabis is a common issue for the grower, temperatures can be increased to help shave a few days off the drying period. Buds should never be dried faster than five days in any situation as it will kill the taste, smell, and quality of the herbs. Slower drying is often associated with tastier and smoother-smoking buds.
Molds are fungi that prefer warm, damp, and humid climates. They develop from spores, travel through the air, and cannot be seen with the naked eye.
Believe it or not, despite its harm to crops, mold is essential to the ecosystem as it decomposes dead plant material, though you never want it on buds.
The best way to prevent bud rot is to ensure grow spaces do not become too humid or damp. Growers can use a dehumidifier if environments become too humid or an AC unit if temperatures are too hot.
One option growers have when bud rot is seen is to harvest infected plants early as this keeps infection from spreading to other plants while making unaffected plant parts potentially salvageable and useable.
Once a bud is rotting there is no saving it, it must be pruned, discarded, and removed from the garden and grow room too. Preventing bud rot on cannabis plants begins with the strain the grower chooses to cultivate.
Sativas are resilient and are best for new growers as their genetics have adapted to humid equatorial climates and grow wispy and airy buds that allow more air to flow through its canopy.
On the other hand, Indica genetics are adapted to dry mountainous regions as they derive from Asia.
Indica-dominant strains produce denser buds and are more susceptible to mold when introduced to humid climates. Growers concerned with humidity and bud rot on cannabis plants should grow strains producing buds that are more airy and resistant to mold.
Other ways to reduce the chance of mold appearing is to:
Humidity is highest in dense and crowded spaces. Imagine strolling through a densely-filled jungle compared to the open floors of a forest. Pruning plants allows more air to flow through them which reduces the collection of moisture.
Some growers will scrog or trellis stems and branches to allow more air to pass through, the more plants can breathe, the better their air circulation, the less likely bud rot is to develop and form.
Nutrients play an essential role in cannabis mold prevention too as plants with healthy immune systems can more easily fend off mold growth. Organically growing cannabis using diverse nutrients is ideal as it increases vital microbes in the soil. This fortifies plant immune systems, strengthens it, and allows them to more effectively ward off mold and pest infestation.
Most importantly, safeguarding plants from excessive moisture is imperative to preventing and battling bud rot. Also too, morning time plant watering can help reduce garden humidity once the sun settles or lights are turned off.
Indoor Mold and Bud Rot Cannabis Prevention
Sustaining consistent grow room temperatures is the best preventative measure a grower can take.
Dehumidifiers, fans, temp control systems, and proper ventilation help to reduce Relative Humidity while making it easier to maintain optimal temperatures and circulation, both are equally important.
This not only creates a stable environment for plants but increases the overall health of the harvest too.
Growers want to avoid overwatering plants as crops receiving more than it can absorb will be subjected to more humidity due to excess water evaporating into the air and in the room.
Providing plants improper nutrients can trigger mold or bud rot on cannabis crops too as these can weaken their immune system and make them more susceptible to mold attacks.
Outdoor Mold and Bud Rot Cannabis Prevention
Outdoor growers, compared to those cultivating inside, are more limited in the ways they can protect crops against mold as they are stripped of the ability to control climates in Mother Nature.
Proper spacing, feeding, and pruning are essential to crop protection.
Once plants are in their final growing spot, either in a pot or in the ground, growers should cage, stake, or trellis plants in order to keep branches far enough apart for air to seamlessly flow through.
Furthermore, pruning the insides and bottoms of plants is especially important, for outdoor growers, in order for air to flow freely underneath the canopy.
Cultivating in an outdoor greenhouse is a great way to protect plants from bud rot, mold, and bugs such as scale insects which cause tremendous harvest loss for growers around the world each year.
Bud rot is more prevalent in regions with humid fall weather, such as Northern California.
Protecting outdoor plants from bud rot is easiest when plants are kept dry and protected from rain and morning dew. They should be spaced apart enough to not touch as this makes it less likely for mold and other bugs to migrate to surrounding plants.
Outdoor growers can use a tarp to cover plants but want to ensure it does not touch plant tops. If they do get wet it is best to gently shake the plant so water build-up and moisture pockets are prevented.
Does rain cause bud rot is a common question among cannabis growers, it causes the disease indirectly as it creates conditions conducive to bud rot. The issue for outdoor growers in rainy regions is that high humidity and dampness supply the moisture mold needs to develop.
Growers in regions prone to bud rot should cultivate strains, such as Auto Amnesia or Cinderella 99, that are acclimated to wetter climates. Alternatively, crops can be timely planted to avoid the onset of rainy seasons, such as planting in the spring and harvesting during summer.
How to Prevent Bud Rot when Drying Cannabis
Bud rot prevention efforts do not end once buds are harvested as mold can occur on cannabis even while drying and curing.
There are measures growers can take during this stage of the harvest, including:
Even if rot is not seen, growers should inspect buds for mold if anything closely resembling it is found as it may be dangerous, suspected areas should be promptly removed and inspected with scrutiny.
Mold can be damaging but is preventable using proper tactics and attention to detail. Growers should not become discouraged if small amounts of mold appear in their garden – They should simply remove it and keep a very close eye on the rest of the crop.
Final Thoughts
Bud rot can destroy an entire crop in a very short time. Once infection takes hold of a cola, a whole crop could be ruined in two weeks or sooner. By following the tips listed above a grower can completely avoid bud rot, however, they should continue to check for rot every day during the last 3 weeks of flowering. Once buds are ripening and have some size, they are always at risk.
