Cannabis is an incredibly hardy and resilient crop; it has natural insecticide properties, can withstand a wide range of temperatures and can bounce back from severe environmental conditions. However, there are some things that can be detrimental to the cannabis plant – and dangerous to those consuming them. One of these things is mould.
Mould is a common type of fungi that most people are familiar with. Whether you’ve seen it in its blue-y green form on an old loaf of bread that has been forgotten about, or as black speckles and dots on damp walls, mould is as diverse as it is off-putting. But it doesn’t only exist in our homes. In fact, it is as ready to cover and devour plants and animals in the natural world as it is to take over our old loaves or unfinished yoghurt pots.
But what about cannabis mould? What is it and, as a grower or consumer, how easy is it to spot?
What is mould?
Mould – or mold, depending on where you’re from – refers to organic structures created by some kinds of fungi. Mould reproduces from spores that can travel through the air both outdoors and indoors. Once these spores come into contact with a suitable surface, such as wet walls or old fruits, they begin to multiply.
While mould will grow on any dead matter in nature, it only becomes visible to us when it forms a large colony, known as mycelium. Mycelium can appear in a variety of forms, colours and textures, depending on the species of fungus. These mould-producing fungi rely on organic matter to survive. By secreting digestive enzymes, mould is able to break down the “food” on which it has grown, feeding the fungus and enabling its spores to spread to more suitable locations – whether that be the fruit bowl, the bread bin, or the cannabis crop.
How does mould affect cannabis?
Anyone who has experience growing cannabis – and to a lesser extent, consuming cannabis – will be aware of the many things that can affect their product. From temperature and humidity to light and nutrient supply, there are many things that can affect the health and quality of the cannabis plant. But getting these considerations wrong can also help to make your cannabis more appealing to certain kinds of mould.
For example, low temperatures or high humidity can increase the plant’s exposure to moisture – something that mould loves. On the other hand, improper storage, or ineffective drying and curing can also invite fungus spores that can eventually lead to a serious mould infestation. While in some settings, mould plays a vital role in recycling organic matter and providing valuable nutrients to the earth, it can also pose serious health implications to humans and other animals which makes it extremely undesirable in cannabis.
What does mouldy weed look like?
Weed affected by mould can be identified in a number of ways depending on the type of mould that is growing there. For example, it may present as fuzzy or powdery in texture with brown, grey, green, black, or even white colouring. So, what are the most common types of mould that can affect your cannabis?
Mildew is among the most common moulds to affect cannabis. You may have heard of mildew when buying cleaning products for your bathroom – and for good reason. However, true mildew is a moisture-loving fungus that especially prefers living plants and other organic matter such as wood. It requires sufficient moisture, reasonable warmth and a food source in order to thrive, which makes cannabis buds and living plants an ideal target. Mildew can often be identified by thin black or white powdery spots on the leaves and buds of the plant.
Bud rot is another common indication that mould has infested your cannabis products. Also known as botrytis or grey mould, it can be recognised by its darker colours which are most obvious on the leaves and flowers of the plant. This type of mould is most likely to affect cannabis plants when humidity and air circulation is not being controlled effectively. It can quickly spread to other plants through the air and water, so isolating any effected plants is crucial to prevent further infections.
As its name indicates, root rot is a kind of fungus that affects the roots of a plant. This type of mould is usually linked to overwatering, poor drainage and high temperatures. This type of infestation is harder to recognise as it affects the part of the plant that is buried beneath the soil; however, brown and wilting leaves can often be an indication of root rot. You can identify root rot by checking the root network of your plant: healthy roots should be white while roots affected by root rot will likely be black and mushy.
In some cases, it may be difficult to distinguish between some types of mould and the natural, cannabinoid-rich trichomes of your cannabis. Trichomes are small, glandular appendages that cover the surface of cannabis leaves and flowers. If in doubt, taking a closer look with a magnifying glass may prove useful. Trichomes are easily distinguished by their shiny and sticky appearance and their mushroom-like tips. On the other hand, mould will usually appear as a fuzzy blanket covering the affected area of the plant.
Being able to recognise mould on your cannabis products – whether it be a living plant or cured buds – is extremely important. While it may be tempting to simply remove the area of the plant on which the mould is growing, this shouldn’t be considered a solution as mould is most likely still present on other parts of the plant – even if you can’t see it. While contact or consumption of mould doesn’t always cause serious harm, it may be associated with nausea, runny or blocked nose, irritation to the skin and eyes, and wheezing. However, in some more vulnerable people, it can cause more significant reactions.
Medical cannabis and mould
Mould can affect all types of cannabis, whether it has been produced for the recreational or medicinal market. However, in recent years, there have been a number of incidents that have raised questions about some licensed medical growers and the safety of patients. There have been a number of incidents involving the recall of medical cannabis products due to the discovery of mould – the most recent recall affecting products in Arizona, US. This most recent incident affected cannabis trim, provided by cannabis company Curaleaf, after signs of possible contamination by a type of fungus known as Aspergillus.
As mentioned previously, the consumption of mould-affected products should always be avoided, as they can cause a number of reactions. In patients who are prescribed cannabis-based products for medicinal purposes, this is often even more important. In some people, particularly those with compromised immune systems, exposure to mould can have significant implications on health. For example, if mould is inhaled into the lungs, it can cause an allergic reaction and, in some cases, even a fungal infection.
What to do if you find mould in your medical cannabis prescription
If you are a medical cannabis patient and you come across what you think might be mould in your cannabis products, you should alert your prescriber immediately. This will allow the provider to take the necessary steps to recall any affected products and make patients aware. Most importantly, never use cannabis products that you suspect may be affected by mould.
