Cannabis Pests and Diseases: 2024 Visual Guide

Hey there green thumbs! So you finally decided to try your hand at growing some cannabis, huh? Well, get ready to deal with a whole new set of challenges, including those pesky little creatures known as cannabis pests and diseases.

Picture this: you’re admiring your beautiful cannabis crops, just minding your own business, when suddenly, you notice something is not quite right. Your leaves and buds, crucial parts of the plant, are looking a little worse for wear, and you start to panic about potential plant diseases. Don’t worry, you’re not alone. Dealing with common pests and diseases is just part of the cannabis grower’s journey.

Don’t worry, fellow cultivators! Your valuable plants can be affected by various pests and diseases, such as spider mites and mold. However, there are methods to effectively deal with these troubles. By adopting integrated pest management techniques and maintaining constant vigilance, you can safeguard your cannabis crops from the prevalent pests and diseases.

So buckle up, because we’re about to dive into the wild world of cannabis pests and diseases. Let’s learn how to keep our plants happy and healthy, despite the challenges they may face. 

Identifying Most Common Cannabis Pests

Timely intervention can effectively address cannabis pests, a key part of disease management in cannabis sativa cultivation. However, significant issues arise when pests are given the opportunity to establish themselves within your grow room. Below, we will discuss certain challenging pests and the appropriate measures to combat them.

Many indoor and greenhouse growers commonly incorporate UVB supplemental lights into their growing areas. The emitted UVB light can effectively reduce or even eliminate pests, preventing their establishment and serving as a useful pest control tool.

To avoid keeping pest-damaged plant tissue or leaves in your grow room, it is advisable to dispose of them elsewhere. Another common way pests and diseases can enter your grow room is through cannabis cuttings or clones from friends. Additionally, exposing your indoor plants to the outdoor sun for a short time can unknowingly introduce pests into your grow room.

Aphids

Cannabis aphids, winged insects, pose a significant problem for growers, whether they cultivate indoors or outdoors, representing a common issue in cannabis pest management. These pests typically inhabit the undersides of leaves, varying in size depending on their growth stage. Utilizing soap-based sprays or introducing aphid predators like Ladybirds, which are available for purchase online, can effectively control aphid activity. However, failure to address an aphid infestation promptly will result in a rapid increase in population and the development of a sticky residue on plants, ultimately diminishing the quality and quantity of the harvest.

Barnacles / scale insects

These creatures, resembling barnacles found by the sea, attach themselves to the stems, branches, and leaves of your plants. They are also known as wax scales. Similar to aphids, they excrete a sticky substance called honeydew that covers your plants. Soap spray, powerful water spray, neem oil, or lacewing and ladybird insects can all be effective in removing them.

Cannabis broad mites

Broad mites can pose a significant problem once established, attacking various parts of the plant in cannabis sativa cultures. Despite their small size, they can wreak havoc on cannabis plants, causing twisted, droopy, glossy, blistered, and overall unhealthy leaves. Identifying the infestation can be challenging, often leading growers to mistake it for pH imbalances, heat stress, or nutrient deficiencies. While chemical sprays like Miticide sprays (e.g., ‘Forbid,’ ‘Avid,’ & ‘IC3’) can be used, many cannabis growers prefer alternatives such as neem oil or soapy sprays. Additionally, introducing mite predators like Neoseiulus or using diatomaceous earth can be beneficial.

Caterpillars & inchworms

You may find that these insects consume your plant leaves and leave behind dark waste. By eliminating them, you can preserve the health of your foliage and promote plant growth. While there are sprays available to combat caterpillars, if your focus is on organic cultivation and enjoying a high-quality smoke, it might be simpler to manually remove the pests.

Crickets

Cannabis leaves are often consumed by crickets, but they can be easily removed by hand. In general, crickets are not significant pests, although ‘Mole Crickets’ can dig into the cannabis root system and cause inconvenience, even though they are rarely encountered. Using plant netting can be helpful in keeping these insects away from your plants.

Fungus Gnats

Fungus gnats commonly arise from the soil after hatching from their eggs. Soils that contain compost created from wood chips may have a higher susceptibility to fungus gnats. Some indoor cultivators intentionally opt for wood-free soil preparations to minimize the risk of fungus gnats, which can harm root systems and impede growth. UVB supplemental lights have a satisfyingly detrimental impact on gnats, as well as other insect pests. Sticky fly tape rolls are also effective against winged insects in cannabis grows. Diatomaceous earth forms a barrier that inhibits the emergence of numerous larvae from the soil. Many growers encounter fungus gnats during cultivation, and although a minor presence doesn’t spell automatic disaster for your crop, it may still diminish plant health and growth rates.

Grasshoppers

Grasshoppers can be easily removed by hand as they feed on the foliage of your plants. To prevent grasshoppers from landing on your plants, you can use netting as a protective layer.

Leafhoppers

Leafhoppers exhibit a wide range of colors, which can be quite perplexing. Their primary disruptive behavior involves extracting plant sap, resulting in the formation of white, brown, or yellow spots. These insects possess wings, six legs, and have the ability to jump. They pose a significant challenge during hot and dry weather conditions, as they require ample moisture and sap, highlighting the importance of managing plant tissue health. While there are specialized insecticidal sprays available, most cultivators would be hesitant to apply such chemicals to their buds, especially if they intend to consume them later. Many prefer to use neem oil or rely on beneficial predators like Ladybirds, Lacewings, and Parasitic Wasps, which are considered allies among cannabis growers.

Leaf Miners

Leaf Miners are larvae that reside within the tissues of cannabis leaves. Their presence becomes evident in the form of meandering white trails on the leaves. Effective remedies include the utilization of Diglyphus isaea, a type of parasitic wasp, as well as the application of neem oil or Spinosad.

Leaf Miners are larvae that inhabit cannabis leaves and leave behind white meandering trails. Effective solutions for controlling Leaf Miners include the use of Diglyphus isaea, a parasitic wasp, as well as neem oil or Spinosad.

Mealybugs

Mealybugs resemble small white wood lice covered in hair. The sticky honeydew they produce can invite black mold, while they offer no benefits to plant well-being. Various treatments like neem oil, soapy solutions, and even alcohol have been experimentally used and found somewhat effective. Ladybird predators can also be helpful in controlling them.

Planthoppers

Planthoppers, tiny insects with wings, excrete a white substance resembling mold. They extract plant sap from parts of the plant, leading to decreased vitality and health, a common issue in cannabis grow operations. The young ones resemble small crabs with red eyes. The recommended method is to use soapy sprays or introduce beneficial predator insects.

Russet Mites

Hemp Russet Mite infestations can be identified by a yellow layer covering branches and causing wilting leaves. These infestations are commonly mistaken for different problems and the mites themselves are barely visible. The symptoms are usually most severe near the top of the plant. Severe cases may require discarding the entire plant, while mild cases can be treated with conventional sprays. However, it may be challenging to justify using insecticidal sprays on buds intended for vaping. Consider utilizing predatory mites like Amblysieus andersoni as an alternative solution.

Slugs / Snails

Foliage can be eaten or damaged by slugs and snails, so it is important to promptly remove them. Typically, they are easily visible and can be manually eliminated from cannabis sativa, resulting in infestations of common cannabis pests and diseases being uncommon.

Spider Mites on Weed Plants

Spider mites can be quite bothersome. They are often seen as tiny dots on the undersides of leaves. The primary indication of their presence is the numerous small white marks on the upper sides of leaves, and in severe cases, you may notice webbing. To control spider mites, it is important to improve air circulation and create an environment with low humidity and high temperatures that are unfavorable for their reproduction. Soapy sprays and specific anti-mite sprays are effective treatments. Introducing predators and using diatomaceous earth may also help in biological control, along with maintaining lower temperatures and higher humidity levels to combat plant diseases. It is crucial to consistently apply treatments to eliminate newly hatched mites. Predatory mites are particularly effective against spider mites.

Thrips

Thrips are small insects with long antennae that can be bothersome in your grow room. They can be dark, yellow/gold, or even colorless. It’s easier to prevent thrips, winged insects that can cause significant plant tissue damage, than to get rid of them once they’re established in a cannabis grow. They can harm plants by damaging the foliage, which reduces health, yield, and potency. Thrip damage leaves light-colored patches on the leaves. The best treatments include using soapy water/neem oil, diatomaceous earth, and conducting regular inspections. Natural predators, particularly Orius and Amblyseius cucumeris, work well in controlling thrips. Predatory mites are the most effective option for biological control against common cannabis pests and diseases.

Whiteflies / White fly

Whiteflies resemble tiny white moths and typically inhabit the undersides of leaves. They cause harm to plants and leave behind a sticky substance that can attract mold. If a plant is infested, shaking a branch will cause the whiteflies to take flight. Two effective methods for dealing with whiteflies are spraying them with soapy water and treating the plants with neem oil. Another viable option for disease management is introducing natural predators like Ladybugs into the cannabis grow.

Identifying the most common cannabis diseases

There are many diseases that affect cannabis. However, if you choose to grow cannabis from seeds instead of clones, which always pose a risk of introducing diseases, and if you keep your grow room clean, you will probably not encounter these diseases.

Bud Rot – Botrytis

Botrytis, or bud rot, is a ruthless ailment that can transform your mature buds into mold. Indications of this include withering leaves and decay at the leaf base. Preventing bud rot, a common fungal issue, involves keeping humidity levels low during the flowering stage of cannabis sativa. Consider utilizing UVA/UVB supplemental light to reduce mold spores. Enhancing airflow, removing excessive foliage, promptly eliminating infected plant portions, and closely monitoring the plant are also effective measures. In severe instances, an early harvest may be necessary.

Root Rot

Root rot is indicated by brown, slimy roots instead of white or cream-colored healthy roots. This condition causes the plant to wilt due to a lack of proper nutrition. Root rot can be caused by various pathogens, fungi, algae, and parasites, resulting in similar problems. Hydroponic cannabis growers are especially prone to this issue, often facing common cannabis pests and diseases. It is important to avoid excessively hot water tanks, nutrient feed with low oxygen levels, and light leaks in the root zone of hydroponic systems, as they contribute to root rot. If left unaddressed, root rot will negatively impact yield and potency. To remedy the situation, beneficial bacteria and the elimination of light leaks can be beneficial. Some growers have also found success in using specialized silver-based anti-bacterial nutrient additives or hydrogen peroxide to restore root health.

Tobacco Mosaic Virus (TMV)

TMV, initially found in tobacco plants, has the ability to impact more than 100 types of plants. It induces distinct pale mosaic/mottled patterns on leaves accompanied by distorted growth. Your plants may exhibit signs of poor health and sluggish development. TMV is an incurable condition that is frequently mistaken for other diseases or problems, posing a challenging (and potentially uncommon) issue for cannabis cultivators.

White Powdery Mold – White Powdery Mildew

If you’ve ever noticed a white powdery substance on your stems or leaves, it’s possible that you’ve encountered White Powdery Mildew or WPM. Catching it early allows for effective treatment, but if left untreated, it can result in the death of your plant. WPM flourishes in conditions of low air circulation and high humidity. Treatment options involve applying a spray solution of 33% milk or a diluted spray of Potassium Bicarbonate (1 tablespoon per gallon of water).

Cannabis Pest Control

Preventing cannabis pests and diseases is much easier and more effective than curing. Detecting early is superior to dealing with infestations. Regularly and attentively monitor your plants, especially since most home growers have only a few plants to tend to. Hence, conducting additional checks won’t consume much time. Resist the temptation to use clones or cuttings, as even reliable sources can encounter significant issues with pests and diseases. It is advisable to grow cannabis from seeds in a grow room that is regularly cleaned.

Preventing Pests On Outdoor Cannabis Plants

If natural predators aren’t able to control the infestation on your outdoor plants, it may be necessary for you to take action. It is highly recommended to purchase and release natural predators on your plants. In severe infestations, you might need to use a soapy detergent spray to eliminate plant-borne pests.

Preventing Indoor Cannabis Pests

Controlling pests in indoor cannabis cultivation can pose challenges as there are typically no existing predators to combat an excess of pests. Consequently, your primary choices are to introduce beneficial insects like Lady Birds or Lacewing, predatory mites, or to adopt a proactive approach by diligently administering plant treatments.

Preventing Cannabis Pests in a Greenhouse

Greenhouses provide significant benefits by shielding plants from harsh weather conditions and lengthening the growing period. However, managing pest infestations in cannabis grow operations can be challenging, particularly in severe instances due to a lack of predator insects, making biological control essential. Replenishing predator insect populations is an option to consider. To maintain optimal greenhouse growth, it is crucial for dedicated greenhouse growers to conduct routine plant inspections.

Resilient & Mould Resistant Cannabis Strains

It would be wonderful to have cannabis strains that are resistant to all pests and disease, unfortunately that isn’t the case. But there are some mould resistant cannabis strains – outdoor strains that are mould resistant are particularly valuable. As always, it’s important to emphasise that the best results come when plants are grown from cannabis seed to harvest under the best conditions that you can provide.

Frisian Dew – outstanding all round outdoor cannabis strain

Frisian Dew is a highly successful and popular outdoor cannabis strain from Dutch Passion. It has a large number of loyal growers and is known for its exceptional reliability, especially in handling the chilly and cloudy summers of northern Europe. Frisian Dew typically reaches harvest readiness by late September or early October in the Northern Hemisphere (March/April in the Southern Hemisphere).

Passion #1

Outdoor cannabis growers in central and southern Europe highly favor Passion #1 seeds due to their suitability for the mild climate and long growing season in these regions. Passion #1 yields are exceptionally bountiful, with buds that are even more potent than Frisian Dew. As an original member of Dutch Passion’s ‘High-THC seed collection,’ Passion #1 guarantees premium strength, great taste, and immensely enjoyable effects for outdoor cannabis enthusiasts.

Durban Poison

Durban Poison stands out as a top sativa strain from South Africa, admired by both indoor and outdoor cultivators. Its genetic makeup is known for its resilience, adaptability, and simplicity in various growing environments. Even in cooler temperate climates, this strain is celebrated for producing extra-large yields outdoors. The buds deliver a truly delightful and potent experience. Highly recommended for growers of all backgrounds!

Integrated Pest Management – Prevention is Always Better

Carefully monitor your plants and aim to ensure that any pest or disease outbreaks are minor. Opting to grow from cannabis seeds instead of clones or cuttings can help prevent the introduction of infestations. Growers using supplemental UVA/UVB lights may have observed their effectiveness in suppressing pests. A well-designed grow room that eliminates areas of hot or stagnant air will also contribute to maintaining optimal conditions. It’s worth noting that by following basic advice, most growers rarely encounter significant issues or infestations. For the majority of growers, successful harvests with minimal worries are the norm. Select high-quality cannabis genetics from a trusted seedbank and enjoy your growing experience!

Cannabis Pests and Diseases

Preventing cannabis pests and diseases is easier and more effective than cure. Detecting early is superior to dealing with infestations. Regularly and attentively monitor your plants, especially since most home growers have only a few plants to tend to. Resist the temptation to use clones or cuttings, as even reliable sources can encounter significant issues with pests and diseases.

Original research and images by Dutch Passion.