Teaching Healthy Cultivation
Visual Symptom Differential Library
Start with location, pattern, progression, and measurements. Each symptom page shows several plausible categories and the checks that help separate them instead of turning one appearance into one diagnosis.
Symptom differential
Lower-Leaf Yellowing
Yellowing that begins on older or lower leaves is a location pattern, not a diagnosis. It can reflect normal senescence, mobile-nutrient limitations, root stress, irrigation problems, salinity, or reduced light exposure.
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New-Growth Chlorosis
Pale or yellow new growth can result from root-zone chemistry, micronutrient availability, rapid growth, root injury, pests, pathogens, or genetic/developmental variation.
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Interveinal Chlorosis
Interveinal chlorosis means tissue between veins becomes paler while veins remain comparatively greener. The leaf age where it begins and the root-zone context are critical evidence.
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Marginal Necrosis / Leaf-Edge Burn
Browning or death along leaf margins can arise from salinity, water stress, nutrient imbalance, heat or desiccation, root problems, or disease. Margin injury should be mapped by leaf age and canopy location.
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Leaf Tip Burn
Necrosis at leaf tips is common but nonspecific. It may appear with high root-zone ionic concentration, water-balance stress, nutrient imbalance, or prior injury.
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Necrotic Spots & Lesions
Dead spots can come from pathogens, pests, droplets, sprays, nutrient-related tissue failure, physical injury, or environmental damage. Lesion shape alone is rarely enough to identify cause.
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Upward Curl / Tacoing
Leaf margins curling upward can be associated with high radiant load, heat, low humidity, airflow, root-water limitations, genetics, or other stress. It should be interpreted alongside leaf temperature and canopy position.
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Downward Clawing
Downward-curled leaflet tips can accompany excess nitrogen availability, root-zone stress, chronic saturation, salinity, genetics, or other physiological stress. Shape alone does not establish nutrient excess.
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Wilting
Wilting indicates insufficient tissue turgor but can occur when the root zone is too dry, too wet, oxygen-limited, damaged, saline, hot, cold, or unable to meet atmospheric demand.
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Bleaching & High-Light Injury
Very pale or bleached upper-canopy tissue can result from excessive light/radiant exposure, heat, chemical injury, or other stress. Location relative to the light source is important evidence.
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Purple or Red Pigmentation
Anthocyanin-related purple or red coloration can be genetic or developmentally normal, and can also increase with temperature, nutrient, root, or other stress. Pigment color alone is not a deficiency diagnosis.
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Stalled or Slow Growth
Slow growth is an outcome shared by many root, environmental, nutritional, pest, pathogen, genetic, and developmental conditions. Growth rate should be compared with stage and recent baseline.
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Distorted New Growth
Twisted, hardened, blistered, narrowed, or malformed new leaves can arise from microscopic mites, chemical injury, root-zone problems, micronutrient availability, systemic pathogens, or developmental abnormalities.
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Root Discoloration & Sloughing
Root color varies with age, substrate, and staining. Loss of fine roots, soft texture, sloughing, poor branching, and declining function are more informative than color alone.
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Stem Lesions & Branch-Specific Decline
Localized stem damage can interrupt support or transport and may result from physical injury, pathogens, constriction, insects, or training wounds. Branch-specific symptoms should trigger direct stem inspection.
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Flower Browning, Collapse & Rot
Browning inside or around flowers can reflect Botrytis and other molds, senescent tissue, mechanical damage, insect injury, heat, or desiccation. Dense flowers must be opened and inspected internally when rot is suspected.
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Corky Blisters, Bumps & Edema-Like Lesions
Raised blisters or corky bumps can result from edema or intumescence, but similar surface changes may also come from pests, chemical injury, residue, or disease. Texture and environmental history are important discriminators.
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Bronzing, Stippling & Surface Scarring
Fine pale dots, bronzing, silvering, or surface scars often trigger a pest suspicion, but spray injury, abrasion, and environmental damage can create similar patterns. Direct evidence of the causal organism matters.
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Leaf Cupping, Strapping & Epinasty
Severely twisted, narrowed, cupped, or downward-bent new growth can arise from herbicide exposure, microscopic mites, root-zone or micronutrient stress, systemic pathogens, or other developmental injury. Distribution and exposure history are critical.
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Sudden Post-Spray Speckling & Scorch
Spotting, bleaching, or scorch that appears after a foliar application should be investigated as a possible exposure event before being labeled disease or deficiency. Droplet pattern and timing are especially useful clues.
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Patchy Container-to-Container Decline
When neighboring plants decline unevenly, distribution can reveal irrigation, drainage, emitter, root disease, pest, media, or placement differences that would be hidden by looking only at one symptomatic plant.
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Wet-Media Wilt & Post-Irrigation Droop
A drooping plant in wet media may have impaired root aeration or root disease rather than a water shortage. The timing of wilt relative to irrigation can completely change the differential.
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