Against the backdrop of the global Covid-19 outbreak and while the theme of infectious diseases is at the forefront of our minds, we'd like to take this opportunity to talk about how important quarantine procedures are in the control of plant pathogens that could potentially spoil our entire homegrown cannabis crop, something that becomes a particular risk when we introduce new clones into our garden.
Cannabis pests and diseases
Here you will find the description and symptoms of pests and diseases that often infect cannabis plants, with photos of various diseases and conditions. When growing cannabis we will observe many pathogens which threaten our plants. Insects like spider mites, thrips, whiteflies, leafminers, etc. and fungi like powdery mildew, botrytis, downy mildew, pythium, are the main enemies for both indoor and outdoor growers. How to identify each pest? Why do they appear? How to manage them? How to avoid pests and diseases? These are common questions that we answer here.
What is neem?
Neem oil is a by-product from a tree endemic to India and Burma and other tropical and subtropical areas, known as neem or nim tree (Azadirachta indica) among other names. It's an evergreen tree (doesn't lose its leaves in autumn) which can reach more than 20 meters in height, and it doesn't need large amounts of water to develop. Nowadays, and due to its multiple uses (from the pharmaceutical industry to agriculture), it can be found virtually in all tropical areas of the planet, except for those at high altitudes. Its relationship with humankind goes back several millennia, as confirmed by some neem leaves found in 4500 years old archaeological sites along the Indus basin, in present-day Pakistan.
Besides its health benefits, neem oil's insecticidal and fungicidal properties are well known in the field of ecological agriculture, since it's a product 100% organic and environmentally friendly. Its main insecticidal compound, azadirachtin, is widely used in all kind of crops as insecticide all over the world both in indoor and outdoor cultivation, and it's an excellent option for ecological agriculture thanks to its repellent and insecticidal properties. Today, we are focusing on this useful substance and will see how it can help us to keep a healthy and pest-free garden.
At this point in the season, when outdoor plants begin flowering and indoor grows are suffering the highest temperatures of the year, it's common for pests to make their first appearance in our garden, which can be particularly difficult to combat precisely because of the high temperatures, that on most occasions will favour their development and propagation. Our plants are therefore more sensitive than ever to insect pests and, later on and once they have developed buds, to the dreaded fungi.
Because of this, it's the season of the year where the most insecticides (early summer) and fungicides (late summer) are used, because no grower wants to watch their efforts and dedication be ruined by a pest or disease. However... are we making the best use of pesticides? How can we limit its impact on our health and the environment? This article was born from my own experience during the years that I spent cultivating cannabis outdoors in my garden, when I saw the fauna in it gradually diminish and, fortunately, how I've seen its resurgence in recent years thanks to a more responsible use of phytosanitary products.
What are Fungus gnats?
What is Alternaria?
Alternaria is a genus of ascomycete fungi. Alternaria species are known to be major plant pathogens, responsible for at least 20% of all agricultural spoilage, and are common allergens in humans, associated with hay fever, asthma, skin problems and are a cause of opportunistic infections in immunocompromised people.
What is Fusarium?
What are aphids?
What is Mildew?
Almost any cannabis grower has had to deal with some type of pest at one time or another. Pests and diseases can be carried by vectors, living organisms that carry insects, spores or viruses without even noticing and spread them around, thus affecting nearby plants. Normally, humans, animals and other plants carried by humans are the most commonly found vectors.
If we want to have a crop free from these annoying plagues, we should follow a number of simple steps: prevention, identification, managment and eradication. Some of the pests affecting marijuana plants can be devastating if not treated early, so proper prevention of these potential threats is crucial. Also, as soon as we observe any problem, we should quickly identify its source: is it an insect? A mold? A virus?
In this post we'll elaborate a brief list of the most common pests and diseases in cannabis plants and tell you how to prevent and get rid of them.
Insects, mites and marijuana plants
There are literally hundreds of insects and mites associated with cannabis. For this reason, we'll only take a look at the most commonly found pests in our beloved plants.
What are viruses?
What are Thrips?
Thrips are one of the most common pests in cannabis crops, especially in indoor growing spaces and greenhouses. These are one of the smallest winged insects, measuring 1.2mm (females) and 0.9mm (males) when adults. Eggs measure around 200 microns and are withish in colour, being layed in the plant tissues. Normally, thrips are found on the underside of the leaves.
There are many varieties of Thrips, being the Frankliniella Occidentalis - also known as western flower thrips - the most commonly found in cannabis plants.