Nutrient Mobility and Symptom Location
Use tissue age and symptom distribution as diagnostic evidence while separating phloem mobility, xylem delivery, and root-zone mobility.
Educational reference · evidence, sources, and limits shown below
Use tissue age and symptom distribution as diagnostic evidence while separating phloem mobility, xylem delivery, and root-zone mobility.
Terms to know
- Phloem-mobile nutrient
- Element that can be substantially remobilized from older source tissue to active sinks.
- Phloem-immobile nutrient
- Element with limited redistribution after deposition, often placing new tissue at greater deficiency risk.
- Symptom chronology
- Order in which visible changes appeared across leaves, tissues, and time.
- Spatial pattern
- Distribution across tissue age, plant, irrigation zone, room, or field.
Core science
Nutrient mobility is not one property. An ion may move readily in solution or soil yet be poorly redistributed in the plant. Xylem transport follows water flow, while phloem redistribution depends on loading, transport chemistry, tissue source-sink relationships, and element biology.
Deficiencies of relatively mobile N, P, K, and Mg commonly appear first in older tissues because the plant reallocates them. Deficiencies of poorly remobilized Ca, B, and often Fe commonly appear in young tissues. S, Mn, Zn, Cu, Mo, and Cl have context-dependent or intermediate behavior. These categories guide observation; they are not immutable symptom rules.
A useful symptom map records tissue age, leaf position, vein or margin pattern, symmetry, affected irrigation zone, progression, and recent events. Nutrient disorders usually develop as gradients, while localized splash, pest, mechanical, thermal, or pathogen injury may follow different geometry.
Why this matters in cultivation
- Symptom location narrows a hypothesis list but does not confirm an element. The next steps are root-zone pH/EC, water and feed review, root inspection, environment, pests, and standardized sampling.
- Recovery is judged primarily in newly developing tissue and halted progression. Necrotic tissue cannot be restored, and old chlorosis may not fully reverse.
Measure and record
Timeline
First observation, progression rate, stage, recent irrigation, environment, spray, transplant, and feed changes.
Tissue map
Node and leaf number, age class, upper/lower canopy, vein/margin/interveinal pattern, and photographs.
Population map
Plants affected, cultivar, zone, emitter, bench, room, edge pattern, and control plants.
Measurements
Input and root-zone pH/EC by method, roots, moisture, temperature, and tissue or solution analysis.
Response
Correction date, variables changed, new-growth condition, progression stop, and follow-up sample.
Common misconceptions
Correction: Several mobile nutrients, senescence, shade, roots, and stress can affect older tissue.
Correction: Mobility is relative and depends on tissue, species, developmental state, and transport pathway.
Correction: Necrosis is irreversible and recovery is better judged by new growth and halted spread.
Evidence limits
Mobility classifications are generalizations across plant species. Cannabis symptom expression varies with genotype, stage, environment, severity, and combined stress.
Related encyclopedia topics
- THC-ENC-070-080, THC-ENC-122-130, THC-ENC-138-140, and THC-GROW-080.
Source notes
- Jones C. and Jacobsen J. Plant Nutrition and Soil Fertility. Montana State University Extension.
- Cockson P. et al. (2022). Visual Symptoms of Nitrogen, Phosphorus, Potassium, and Magnesium Deficiency in Hemp. e-GRO Edible Alert 8.11.
- THC Cannabis Plant Science Source Packet v1.1 (project source, May 2026).
- THC Cultivation SOP Source Materials Packet v1.0 (project source, May 2026).
This lesson summarizes the source material and its evidence limits for education. Use direct measurement, controlled comparison, and the cited sources when conditions differ or a decision carries meaningful risk.