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.

Erwinia, what is it and how does it affect plants?

Erwinia, what is it and how does it affect plants?

In the vast kingdom of microorganisms, Erwinia emerges as a genus of bacteria in the family Erwiniaceae that has captured the attention of scientists, farmers and biotechnologists alike. Although some strains of Erwinia have been recognized for their pathogenic role in plants, others have proven to be allies in industrial production and scientific research, a fact that only increases interest in it.

Today we invite you to learn in more detail what Erwinia is and how it affects crops, exploring everything from the symptoms of infection that plants present to its impact on agriculture or how to prevent and treat it.

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What is Septoria or Septoriasis in cultivation?

What is Septoria or Septoriasis in cultivation?

If you have ever cultivated, even if you have never done it before, surely you know that fungi are one of the main enemies of crops throughout the world. These microscopic organisms can spread rapidly in plants, causing a variety of diseases that can significantly reduce crop production and quality. Fungal pests can affect a wide range of plants, from cereals and vegetables to fruits, forest crops, and of course cannabis, causing damage with a significant economic impact for farmers and the food industry.

Septoria is a fungal disease that affects a wide variety of plants, including crops such as tomatoes, potatoes, and wheat. This disease is caused by fungi of the genus Septoria, which spread through spores and are characterized by the appearance of small, dark spots on the leaves of the plant, which eventually spread and become necrotic. In this article, we will explore the causes, symptoms, and preventive and control measures of this disease to help you protect your crop.

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Plant Quarantine: Isolation is prevention!

Plant Quarantine: Isolation is prevention!

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.

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Properties of Neem oil

Properties of Neem oil

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.

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Responsible use of pesticides in cannabis cultivation

Responsible use of pesticides in cannabis cultivation
Biological pest control using natural predators can give great results

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.

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Alternaria in the cannabis crop

Alternaria in the cannabis crop

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.

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Fusarium and cannabis plants

Fusarium and cannabis plants

What is Fusarium?

Fusarium is, in fact, the name of a genus of filamentous fungi that live in the soil in association with plants, including cannabis. Most species are saprophytes, i.e. they feed on the debris of other organisms. Thus, Fusariosis is the name given to the disease caused in plants by certain species of Fusarium fungi (phytopathogens), which in this case develop as parasites.

They form an important contaminating agent in laboratories, and some Fusarium species attack cereals and produce mycotoxins which can affect humans and produce diseases like fungal keratitis, onychomycosis Panama disease, also several types of skin infections.

The Soviets have been accused of using Fusarium as a biological weapon in Laos, Cambodia, and Afghanistan, while in the United States, it was proposed as a weapon to eradicate coca plantations in Colombia.

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Mealybugs on cannabis plants

Mealybugs on cannabis plants

Mealybugs can represent a serious pest for marijuana plants. While they rarely attack indoor plants, they are normally found in outdoor crops.

In today's article we are going to see the main characteristics of this sucking insect, as well as what we can do to prevent their appearance or to get rid of them in the most effective way possible.

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Introduction to cannabis pests and diseases

Introduction to cannabis pests and diseases
Female of the red form of the spider mite Tetranychus urticae with two silk wires. The substartum is a bean leaf. Scale : mite body length ~0.5 mm Technical settings : - focus stack of 39 images - microscope objective (Nikon achromatic 10x 160/0.25) on bellow

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.

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Cannabis viruses

Cannabis viruses

What are viruses?

The origins of viruses are still unclear. We can find three main theories explaining their origins and evolution: the Regressive hypothesis - viruses were once small cells that parasite larger cells that lost part of their genetic material over time - the Cellular origin hypothesis - viruses would have formed from bits of DNA or RNA coming from larger organisms - and the Coevolution hypothesis - viruses would come from protein molecules and nucleic acid.

Basically, plant viruses are intracellular parasites that can't replicate without a host (cell). We know much less about plant viruses than we do about their animal counterparts. We know about few viruses which attack cannabis plants, although they can quickly devastate a crop. One of these viruses is the Tobacco mosaic virus (TMV), the first virus ever discovered; the disease was first identified by Adolf Mayer in 1886. In 1898, Martinus Beijerinck replicated Dimitri Ivanovsky's (1892) experiments and used the term of "virus" to indicate that the cause of tobacco mosaic disease was not bacteria.

Most of the plant viruses we know are specific for certain species, which means they need certain types of host cells to replicate, thus being limited to a few host species. Still, there are several viruses that can attack a vast range of species, which are the most aggressive ones.

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What is Pythium?

What is Pythium?

The different varieties of marijuana share many pests and diseases that can also affect other plant species. These vary depending on the cultivation method and the region.

Intensive farming, and its new technologies, have caused the proliferation of many different pathogens and parasites in farms all around the world. The use of pesticides and herbicides has greatly transformed conventional agricultural methods and techniques. Learning about these different plagues and illnesses that affect marijuana can help us identify them and, therefore, combat them appropriately.

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How to get rid of Thrips in cannabis plants

How to get rid of Thrips in cannabis plants

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.

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About this Cannabis Blog

This is the official blog of Alchimia Grow Shop. This blog is intended exclusively for the use of adults over the age of 18 years.

To buy equipment for growing cannabis at home you can consult our catalogue of cannabis seeds, grow shop and paraphernalia


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