Is your cannabis plant looking unhealthy? Diagnosing problems early is crucial for a successful grow. This visual guide to Marijuana Leaf Diagnosis helps you quickly identify common issues affecting your cannabis plants. From nutrient deficiencies and pest infestations to diseases and environmental stressors, learn to recognize the symptoms on your marijuana leaves and find the right solution. Click on the images and descriptions below to delve deeper into each cannabis plant problem and discover how to fix it.
Spotting Nutrient Deficiencies in Marijuana Leaves
Nutrient deficiencies are a frequent cause of cannabis plant issues. By carefully examining your marijuana leaves, you can often pinpoint which nutrient is lacking and take corrective action.
Boron Deficiency
Boron deficiency in cannabis, though uncommon, can lead to distinctive symptoms. Look for brown patches on the leaves and new growth that appears thick and twisted. This deficiency is often associated with underwatering or excessively dry conditions.
Calcium Deficiency
Identifying a calcium deficiency is key to maintaining healthy cannabis plants. Brown spots appearing on the leaves are a primary indicator. Calcium is vital for the structural integrity of the plant and its ability to cope with environmental stresses.
Copper Deficiency
A cannabis copper deficiency manifests with unique leaf symptoms. The leaves may turn a dark, almost shiny color, often with blue or purple undertones. Additionally, the edges and tips of the leaves will typically turn yellow.
Iron Deficiency
Cannabis iron deficiency is usually noticeable on new growth. The top and inner leaves of the plant will begin to turn yellow or even white, indicating a lack of iron.
Magnesium Deficiency
Magnesium deficiency in marijuana plants presents with yellowing between the veins of the lower, older leaves. The veins themselves often remain green, creating a distinct pattern on the leaf.
Manganese Deficiency
Look for yellowing between the veins of leaves, accompanied by mottled brown spots to identify a manganese deficiency. These brown spots are dead patches that can indicate this nutrient imbalance.
Molybdenum Deficiency
A cannabis molybdenum deficiency can initially resemble a nitrogen deficiency, with yellowing of older, lower leaves. However, leaves might also develop a mottled appearance or take on a red or pink hue.
Nitrogen Deficiency
Nitrogen deficiency is common in cannabis and easily recognized. The older, lower leaves will turn yellow, wilt, and eventually drop off if the deficiency is not addressed.
Phosphorus Deficiency
A phosphorus deficiency typically shows on the lower, older leaves of the cannabis plant. These leaves may develop dark splotches and eventually fall off.
Potassium Deficiency
Potassium deficiency in marijuana often reveals itself through burnt leaf tips and edges. Yellowing between the leaf margins is another key symptom, usually appearing on older leaves first.
Sulfur Deficiency
Sulfur deficiency, while rare, causes a general yellowing of cannabis leaves, known as chlorosis. This yellowing typically starts from the back of the leaf and spreads.
Zinc Deficiency
For zinc deficiency, check the younger leaves. They will start yellowing between the veins, and the leaf tips may become discolored and begin to die.
Identifying Pests and Insect Damage on Cannabis Leaves
Pests and insects can quickly damage cannabis plants. Early detection through marijuana leaf diagnosis is vital to prevent infestations from taking over your grow.
Aphids
Aphids are soft-bodied insects that can be white, green, yellow, black, brown, or red. They often cluster under leaves and are accompanied by white specks, which are baby aphids and their exoskeletons.
Barnacle Scales
Barnacle scales are unusual pests that remain stationary on stems and under leaves. These scale insects suck sap from the plant, weakening it over time.
Broad Mites
Broad mites are microscopic pests that cause significant damage. Symptoms include droopy or twisted new growth, especially at the plant’s top, along with blistered and glossy leaves.
Caterpillars & Inchworms
Caterpillars and inchworms are leaf-eating pests that leave noticeable holes in cannabis leaves. You might also spot their droppings or the caterpillars themselves on the plant.
Crickets
Crickets are opportunistic pests that will feed on cannabis plants, creating small, irregular holes in the leaves. Mole crickets may also damage roots by digging in the soil.
Four-lined Plant Bug
Damage from four-lined plant bugs is often mistaken for leafhopper damage. These bugs cause distinctive spotting on cannabis leaves.
Fungus Gnats
Fungus gnats are tiny flies that buzz around the soil surface, especially in wet conditions. While the adults are mostly a nuisance, their larvae can damage roots and seedlings.
Grasshoppers
Grasshoppers are voracious eaters that leave large, irregular holes in cannabis leaves. Locusts, a winged type of grasshopper, cause similar damage.
Hemp Russet Mites
Hemp russet mites are extremely small and difficult to see. Infestations can cause yellowing masses of bugs and drooping tops of cannabis plants.
Leaf Miners
Leaf miners are pests that live inside the leaf tissue, creating pale, winding trails across the leaf surface. This damage is distinctive and easy to identify.
Leafhoppers
Leafhoppers feed on cannabis leaves, leaving behind brown or yellow spots. They can also transmit plant diseases.
Mealybugs
Mealybugs appear as white, hairy bugs on cannabis plants, often leaving white patches that resemble mold or webbing. They thrive in warm conditions.
Planthoppers
Planthoppers are pests that can infest cannabis, leaving a unique cotton-like growth on the plant as they suck its sap. They can appear in various forms.
Slugs or Snails
Slugs and snails chew on cannabis leaves, leaving behind large, irregular bites and often a slime trail.
Spider Mites
Spider mites cause small spots on cannabis leaves, often accompanied by fine webbing. They are related to spiders and can quickly multiply in favorable conditions.
Stink Bugs
Stink bugs can attack cannabis plants, laying distinctive patches of white eggs on the leaves. Young stink bugs may cluster around these egg patches.
Thrips
Thrips are small, fast-moving insects that can vary in appearance. They cause damage to cannabis leaves, leaving a mottled or silvery appearance.
Whiteflies
Whiteflies resemble tiny white moths and behave somewhat like spider mites. They can infest cannabis plants, sucking sap and weakening them.
Recognizing Diseases and Mold Issues on Marijuana Leaves
Diseases and mold can devastate cannabis crops. Prompt marijuana leaf diagnosis is essential to manage and control these issues.
Beet Curly Top Virus
Beet Curly Top Virus (BCTV) is a cannabis disease that causes a range of symptoms, including curling and twisting leaves, yellowing, and overall stunted growth.
Bud Rot or Mold
Bud rot is a mold issue that affects cannabis buds, often indicated by dying leaves appearing on the buds themselves. Dense buds in humid conditions are particularly susceptible.
Leaf Septoria / Yellow Leaf Spot
Leaf septoria, also known as yellow leaf spot, is caused by a fungus or bacteria. It manifests as round yellow or brown spots on cannabis leaves.
Root Rot
Root rot is a serious condition caused by pathogens in hydroponic systems or waterlogged soil. Symptoms can include curled, drooping, and unhealthy leaves, reflecting the root damage below.
Tobacco Mosaic Virus (TMV)
Tobacco Mosaic Virus (TMV) causes distinctive symptoms on cannabis, including odd yellow markings and twisted growth. Leaves may appear splotchy or mottled.
White Powdery Mildew
White powdery mildew (WPM) appears as white, powdery patches on cannabis leaves and stems. It can resemble flour and, if untreated, can spread and become problematic.
Environmental Stress and Marijuana Leaf Symptoms
Environmental factors play a crucial role in cannabis health. Marijuana leaf diagnosis can help identify stress caused by heat, light, water, or wind.
Heat Stress
Heat stress causes cannabis leaves to cup upwards, resembling tacos. This is a reaction to excessive heat, as the plant tries to reduce its surface area and transpiration.
Light Burn or Light Stress
Light burn or light stress occurs when cannabis plants receive too much light. Symptoms include yellowing leaves or leaf tips, particularly those closest to the grow light.
Over-Watering
Over-watering is a common mistake. Signs include drooping and wilting leaves after watering. The leaves often feel firm and curl downwards.
pH Fluctuations
pH fluctuations can hinder nutrient uptake, leading to various symptoms, including brown spots on middle or lower cannabis leaves.
Under-Watering
Under-watering causes cannabis plants to wilt and droop. The leaves become limp, lifeless, and often feel papery to the touch.
Wind Burn
Wind burn occurs when cannabis plants are exposed to excessive wind, often from fans. It results in curled or clawing leaves in the direct airflow.
Other Cannabis Plant Problems Indicated by Leaf Symptoms
Beyond nutrients, pests, and environment, other issues can affect cannabis plants. Marijuana leaf diagnosis helps identify these less common problems as well.
Accidental Re-Vegging
Accidental re-vegging happens when a flowering cannabis plant reverts back to vegetative growth. This causes unusual new growth and leaves with smooth, single-finger edges.
Hermies, Pollen Sacs & Bananas
Identifying hermaphroditic traits is crucial in cannabis cultivation. Look for pollen sacs or “bananas” developing on female plants, indicating potential self-pollination.
Nutrient Burn
Nutrient burn, or fertilizer burn, is a common issue from over-fertilizing. It manifests as burnt leaf tips, which turn yellow or brown and become crispy.
Nitrogen Toxicity
Nitrogen toxicity results from excessive nitrogen. Cannabis leaves become dark green, often shiny, and the tips turn downwards, creating a “clawing” effect.
Root Problems
Root problems in cannabis can cause a wide array of above-ground symptoms, making diagnosis challenging. General signs of unwellness, like drooping or curling leaves, can indicate root issues.
Early and accurate marijuana leaf diagnosis is key to maintaining healthy cannabis plants and achieving a bountiful harvest. Use this visual guide to quickly identify problems and take appropriate action. For a comprehensive solution to many cannabis growing challenges, explore the 5-Step Remedy to 99% of Cannabis Growing Problems.
