Diagnostics & Abiotic Disorders
Symptom reasoning, nutrient and environmental disorders, root stress, light injury, water stress, and differential diagnosis.
Published lessons
These pages are organized here by subject. The permanent THC-ENC IDs remain stable behind the scenes even when a clearer display title is used.
A Diagnostic Workflow: Pattern Before Product
Use a repeatable cannabis plant-diagnostic workflow that begins with pattern, history, measurements, and competing explanations before selecting or evaluating a corrective action.
Symptom Distribution by Plant Age and Location
Interpret cannabis symptom position through tissue age, nutrient mobility, vascular supply, exposure, and canopy microclimate without treating location as proof of one cause.
Chlorosis Patterns
Describe cannabis chlorosis accurately and use uniform, interveinal, marginal, mottled, localized, and developmental patterns to build competing hypotheses instead of naming a deficiency from color alone.
Necrosis, Scorching, and Margin Injury
Differentiate cannabis dead-tissue patterns by boundary, tissue age, exposure, water relation, root-zone history, chemical history, and progression rather than diagnosing every brown tip or margin as nutrient burn.
Leaf Curling, Cupping, and Distortion
Classify cannabis leaf-shape changes and connect them to differential growth, turgor, exposure, injury, pests, root function, and development without treating ‘clawing’ or ‘tacoing’ as cause-specific diagnoses.
Wilting With Wet Versus Dry Media
Separate water-supply shortage, excessive atmospheric demand, hydraulic interruption, root dysfunction, and wet-root-zone uptake failure when cannabis wilts.
Oedema and Water-Imbalance Disorders
Recognize oedema as a physiological water-imbalance hypothesis and distinguish blistering or corking from pests, pathogens, spray deposits, salts, and other injury.
Heat Stress
Diagnose cannabis heat stress using tissue temperature, duration, radiation, transpiration, roots, and functional response rather than room-air temperature alone.
Cold and Chilling Stress
Distinguish chronic cool growth, chilling, freezing, cold-root effects, condensation, and cold-plus-light injury in cannabis without treating one temperature or the absence of frost as a universal diagnostic threshold.
High-Light and Photoinhibition Injury
Separate high photon exposure, leaf heating, reversible photoprotection, sustained photoinhibition, bleaching, and other top-canopy injuries using measured light, temperature, plant-water status, acclimation, and functional evidence.
Low-Light Etiolation and Stretch
Explain elongation under insufficient or poorly distributed light and distinguish true etiolation from shade avoidance, genotype, temperature effects, crowding, and normal developmental transition.
Humidity and Transpiration Imbalance
Diagnose humidity-related problems through vapor pressure, leaf temperature, root supply, airflow, wetness, and developmental response rather than relative humidity alone.
Root-Zone Hypoxia
Explain oxygen limitation in roots and distinguish hypoxia from pathogens, salinity, drought, temperature injury, and nutrient deficiency using root-zone state, duration, aeration, and plant response.
Salinity and Osmotic Stress
Separate total soluble-salt effects, osmotic stress, ion-specific toxicity, alkalinity, and nutrient imbalance using measured EC, ion composition, water status, root condition, and genotype/stage context.
pH-Driven Nutrient Unavailability
Explain how root-zone pH can alter nutrient chemical form, solubility, exchange, microbial processes, and uptake while avoiding universal availability charts or visual deficiency diagnosis.
Water Alkalinity and Sodium Problems
Distinguish irrigation-water pH, alkalinity, hardness, salinity, sodium, chloride, and bicarbonate so long-term root-zone chemistry is diagnosed from a complete water analysis rather than one meter reading.
Chemical Phytotoxicity
Investigate suspected chemical injury by reconstructing source, route, formulation, mixture, exposure pattern, environment, tissue state, and timing without treating visual symptoms as proof or authorizing chemical use.
Mechanical Damage and Training Injury
Identify compression, tearing, abrasion, girdling, impact, wind, trellis, tie, and training injury and distinguish mechanical damage from disease or other abiotic disorders using contact geometry, vascular function, progression, and recovery.
Spray, Residue, and Foliar-Burn Investigations
Investigate foliar injury from droplets, deposits, salts, oils, adjuvants, mixtures, light, drying conditions, drift, and equipment contamination without re-exposing the production crop or diagnosing from residue appearance alone.
Sampling, Corrective Action, and Verification
Design representative diagnostic samples, controlled corrective actions, acceptance criteria, and follow-up measurements that test the leading hypothesis without erasing evidence or overstating certainty.