Broad mites on cannabis: Signs, symptoms, and solutions

As a cannabis grower, you know that pests can be a real headache, but few are as sneaky and destructive as broad mites. 

If left unchecked, these tiny pests (scientifically known as Polyphagotarsonemus latus) can quickly cause serious damage to your plants.

But don't worry; we’re here to help you identify, prevent, and treat these troublesome mites so you can keep your plants healthy and thriving.

Disclaimer: Any information given on this site is for educational purposes only. Please ensure if you’re growing cannabis, you’re doing so by the law and subject to appropriate permissions and licenses of the applicable country.

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What are broad mites?

They are tiny pests that feed on the sap of cannabis or other host plants. They’re so small that you’ll need a strong hand lens to spot them. 

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What do broad mites look like

They have oval-shaped bodies, are slow-moving, and come in colours ranging from translucent to light yellow to green, depending on what they’re feeding on. Females often feature a white stripe on their back. 

Adult females are about 0.2mm long, and immature mites or broad mite larvae in the quiescent stage have only three pairs of legs, while adults have four.

Broad mite eggs are laid on the underside of leaves and look like tiny, clear, or white spheres. With their rapid reproduction rates, acting fast at the first signs is crucial.

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Broad mite damage on cannabis: Signs and symptoms

A broad mite invasion can cause extensive damage to your cannabis plants, often attacking new growth, leaves, and buds. 

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How do you know if you have broad mites?

The first signs of cannabis broad mites often appear on young expanding leaves, which may show stunted growth, pale yellow discolouration, and distorted growth patterns. 

Symptoms include foliage curling, thickening, or turning bronze in severe cases.

Broad mites damage the plant cells of infested plants, resulting in twisted and deformed leaves, particularly at the top of plants.  

The damage symptoms caused by these mites can be easily mistaken for nutrient deficiencies or environmental stress, so careful monitoring is key. 

If you spot any of these damage symptoms, it's time to act quickly to protect your crop.

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Broad mite identification and monitoring

To catch a broad mite infestation early, regularly inspect your plants, especially the underside of leaves and buds where they like to hide. 

Pay close attention to areas of the plant that seem affected first - like the growing tips and young foliage. 

A strong magnifying glass (20x) or a microscope can help you identify adult broad mites and their eggs. 

Remember, these pests are incredibly small, so look closely!

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Understanding the broad mite life cycle

Knowing the life cycle is essential for effective control. 

A broad mite passes through several stages: egg, larva and nymph (quiescent nymph stage) before it becomes an adult broad mite.  

Each stage has different vulnerabilities. For example, eggs are resistant to many chemical treatments, but larvae and nymphs are more susceptible.  

Timing your treatments according to their life cycle can significantly affect your success rate.

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What are the differences between male and female broad mites?

There are some key differences between males and females: 

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1. Size and appearance

Female mites are slightly larger than males, measuring around 0.2 mm in length. They are usually light yellow to translucent. 

Males, on the other hand, are smaller and often have a more elongated, slender body shape.

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2. Leg structure

Females have four pairs of legs, while male mites, although also having four pairs, are generally more agile and use their legs differently, especially during mating.

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3. Behaviour

Male mites are more active and play a distinct role in reproduction. They carry immature females (quiescent nymphs) to new leaves, feeding sites or mating locations once they become adults. 

This unique behaviour helps spread the population to new areas of the plant.

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4. Reproductive role

Females are primarily responsible for laying eggs. Each adult female can lay up to 40 eggs during her lifespan, which is a critical factor in how quickly an infestation can grow. 

Male mites don’t lay eggs but fertilise the females and maintain the population.

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Preventing broad mites: Proactive measures

To prevent broad mites on cannabis plants, start with good cultural practices. 

Maintain a clean growing environment, regularly check for pests, and manage humidity levels. 

High humidity encourages broad mite populations, so ensure proper ventilation, especially if you grow in greenhouses.

Introducing predatory mites, such as Amblyseius andersoni, is an effective proactive biological control measure. 

These natural enemies support keeping broad mite numbers in check. Hang them on plant stems early in the season to combat mites during their lifespan. 

This biological control method is an organic way to reduce mite populations without using chemical pesticides.

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Treating broad mite infestations: Reactive methods

If you already have a broad mite infestation, don’t panic - there are several treatment options.

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Organic treatments

Use insecticidal soap, neem oil, or horticultural oil to control mites without harming beneficial insects. 

Neem oil is effective but may require repeat applications for thorough control. Predatory mites can also be introduced to target mites naturally.

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Chemical treatments

In serious cases, chemical insecticides or miticides may be necessary. Products like Avid are among the best insecticides for broad mites on cannabis. 

Follow the manufacturer's instructions carefully, and rotate chemicals to avoid resistance buildup.

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Choosing the right control method: Organic vs chemical

Organic methods like predatory mites, insecticidal soaps, and horticultural oils are eco-friendly and safer for your plants but might require more frequent applications to control broad mites. 

Chemical controls, such as specific miticides, provide an immediate knockdown effect but can harm beneficial insects and lead to resistance over time.

Ultimately, the choice between organic and chemical methods depends on your specific situation, the severity of the infestation, and your growing philosophy. 

Regular monitoring and combining these approaches can offer a balanced and effective solution for managing broad mites on cannabis.

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Tailored treatments for different infestation stages

The best treatment approach to killing broad mites depends on the severity of the infestation. 

Organic methods like predatory mites or insecticidal soap may suffice for light infestations. 

In contrast, more severe cases may require chemical treatments to prevent plant death. 

Always tailor your approach to your plants' specific needs and the extent of the damage.

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Takeaways

Broad mites can be a real challenge, but with early detection, proactive measures, and the right treatments, they can be effectively controlled. 

Regular monitoring, understanding their lifespan, and choosing the right mix of organic and chemical methods will help you protect your cannabis plants and maintain healthy growth. 

Keep an eye on your plants, act swiftly at the first signs of broad mites, and you’ll be well-equipped to keep these pesky mites at bay.

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Happy growing!

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FAQs

What is the difference between spider mites and broad mites?

Spider mites and broad mites are both tiny pests that can cause serious damage to cannabis plants, but they differ in appearance, behaviour, and the type of damage they inflict.

Spider mites are larger and are usually red or brown, making them easier to spot. They produce fine webbing on the undersides of leaves, a clear indicator of their presence. 

Spider mites feed on plant tissue, causing yellow or white speckling on leaves. Over time, this can lead the infected plant to show bronzed foliage and, in serious cases, plant death. 

Broad mites, on the other hand, are much smaller - almost microscopic. They are slow-moving and pale yellow or pale in appearance. They prefer to hide in flower buds, young leaves, and the growing tips of plants. 

Broad mites secrete substances that are toxic when feeding, causing twisted, deformed growth and distorted leaves. 

Damage caused by broad mites is often mistaken for environmental stress or nutrient deficiencies.

While both pests thrive in temperate regions and can stunt plant growth, spider mites are more likely to cause fruit drop and extensive damage to plants because of their rapid reproduction. 

Broad mites, especially their eggs, are more resistant to certain treatments, making them trickier to manage. 

Understanding these differences can help you choose the right treatment strategy and maintain healthy plants.

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