A Visual Guide to Cannabis Pests and Diseases

Aphids

Aphids are tiny, soft-bodied insects that suck plant sap from leaves and excrete honeydew, which can lead to mold. These pests are particularly problematic in both indoor and outdoor grows, as they can quickly form large populations.

• Damage: Discoloration, leaf deformation, stunted growth, sooty mold
• Control: Neem oil, insecticidal soap, ladybugs, lacewings

For more details on aphids and how to effectively combat them, read our comprehensive article: Combatting Aphids on Cannabis.

Spider Mites

Spider mites are tiny pests that leave fine webs on leaves and cause yellow spots. They are problematic in both indoor and outdoor grows.

• Damage: Yellow spots, discoloration, stunted growth
• Control: Predatory mites, UVB supplemental lights, diatomaceous earth

Learn more about controlling spider mites in our detailed article: Eliminating Spider Mites on Cannabis.

Thrips (Thysanoptera)

Thrips are small, slender insects that suck sap from leaves and leave silver streaks. They are a serious problem in both indoor and outdoor grows. Thrips not only cause physical damage but can also transmit viruses that further weaken the plants.

• Damage: Silver streaks, virus transmission
• Control: Lacewings, neem oil, diatomaceous earth

For more information on thrips and their control, visit our detailed article: Treating Thrips on Cannabis.

Whiteflies (Aleyrodidae)

These tiny flies suck plant sap and leave honeydew, which encourages mold growth. They are especially troublesome in indoor grows and can cause significant damage if not controlled early.

• Damage: Honeydew, mold formation
• Control: Insecticidal soap, lacewings, air circulation

Learn more about whiteflies and how to control them in our specialized article: Eliminating Whiteflies on Cannabis.

Fungus Gnats

Fungus gnats are small, dark insects whose larvae can damage plant roots. They are particularly problematic in moist conditions often found in indoor grows.

• Damage: Root damage
• Control: Yellow sticky traps, drainage, nematodes

For more details on controlling fungus gnats, read our comprehensive article: Combatting Fungus Gnats on Cannabis.

Leaf Miners (Liriomyza spp.)

Leaf miners lay their eggs in leaves, and the larvae create tunnels through the plant tissue, significantly affecting photosynthesis. This damage is especially problematic in indoor grows, where plants are concentrated in a limited space.

• Damage: Leaf tunnels, reduced photosynthesis
• Control: Remove affected leaves, yellow sticky traps, plant hygiene

Learn more about leaf miners and their control in our detailed article: Controlling Leaf Miners on Cannabis.

Scale Insects

Scale insects are small bugs that attach themselves to plant stems and suck sap. These pests can significantly weaken the plants and are particularly persistent in indoor grows.

• Damage: Weakened plants, stunted growth
• Control: Neem oil, insecticidal soap, regular inspections

For more information on controlling scale insects, read our specialized article: Controlling Scale Insects on Cannabis.

Mealybugs

Mealybugs, also known as woolly aphids, are small insects that excrete a waxy substance and suck plant sap. These pests can cause significant damage and produce honeydew, which encourages mold growth.

• Damage: Honeydew, mold formation
• Control: Neem oil, insecticidal soap, ladybugs

Learn more about controlling mealybugs in our comprehensive article: Eliminating Mealybugs on Cannabis.

Snails and Slugs

Snails and slugs are voracious pests that leave slime trails and holes in leaves. They are particularly problematic in outdoor grows and can destroy entire plants in severe infestations. These pests are mainly nocturnal and hide under plant debris or in moist soil during the day.

• Damage: Slime trails, holes in leaves
• Control: Handpicking, snail bait, copper tape

For more details on controlling snails and slugs, read our comprehensive article: Controlling Snails on Cannabis.

Caterpillars

Caterpillars are voracious pests that can eat both leaves and flowers. They are difficult to spot as they camouflage well and often hide inside the plants. Severe infestations can cause significant damage and greatly affect the yield.

• Damage: Eaten leaves and flowers
• Control: Handpicking, biological insecticides, natural predators

Learn more about controlling caterpillars in our comprehensive article: Eliminating Caterpillars on Cannabis.

Leafhoppers (Cicadellidae)

Leafhoppers are sap-sucking insects that can transmit viruses that harm plants. They cause leaf discoloration and can stunt plant growth. A large infestation can severely weaken plants.

• Damage: Leaf discoloration, stunted growth
• Control: Neem oil, insecticidal soap, natural predators

For detailed information on controlling leafhoppers, read our specialized article: Controlling Leafhoppers on Cannabis.

Grasshoppers (Acrididae)

Grasshoppers eat large amounts of plant material and can cause significant damage. They are particularly problematic in outdoor grows and can destroy entire fields in severe infestations.

• Damage: Eaten leaves, stunted growth
• Control: Nets, natural predators, biological insecticides

Learn more about controlling grasshoppers in our comprehensive article: Controlling Grasshoppers on Cannabis.

Bud Rot

Bud rot is caused by fungi and leads to rotting flowers. This disease can spread quickly and destroy large parts of the crop if not detected early.

• Damage: Rotting flowers
• Treatment: Resistant strains, air circulation, remove affected flowers

Learn more about bud rot and its treatment in our specialized article: Treating Bud Rot on Cannabis.

Root Rot

Root rot is caused by excessive moisture and leads to rotting roots. This disease can kill the plant if not treated promptly.

• Damage: Rotting roots
• Treatment: Proper pH, good drainage, avoid overwatering

For more details on treating root rot, read our comprehensive article: Treating Root Rot on Cannabis.

Powdery Mildew

Powdery mildew is a fungal infection that appears as white, powdery spots on leaves. It can spread quickly and severely affect the health of the plants.

• Damage: White, powdery spots on leaves
• Treatment: Neem oil, specialized fungicides, reduce humidity, remove infected leaves

Learn more about controlling powdery mildew in our comprehensive article: Treating Powdery Mildew on Cannabis.

Nutrient Deficiencies in Cannabis Plants

Nutrient deficiencies occur when cannabis plants do not receive enough essential nutrients. Typical symptoms include discoloration, stunted growth, and low yields. These issues can be caused by a lack of nitrogen, phosphorus, potassium, or other micronutrients.

• Damage: Discoloration, stunted growth, low yields
• Treatment: Check nutrient program, add specific nutrients, monitor pH levels

For more information and suitable products to address nutrient deficiencies, visit our article on Nutrient Deficiencies in Cannabis Plants.