What are the visual symptoms of magnesium deficiency in tomatoes?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Identifying magnesium deficiency tomatoes starts with leaf examination. The older leaves exhibit interveinal chlorosis, where the yellowing spreads between the veins, while the veins remain green. This pattern differs from the uniform yellowing typically associated with many nitrogen problems. I have diagnosed hundreds of plants using this as a key identifier.
Leaf Pattern Development
- Interveinal chlorosis appears first on mature lower leaves
- Yellow marbling spreads outward from leaf centers
- Veins maintain dark green coloration creating sharp contrast
- Affected areas eventually turn necrotic brown and crumble
Progression Timeline
- Symptoms appear 3-4 weeks after deficiency begins
- Starts on oldest leaves near plant base
- Advances upward to middle foliage over 10-14 days
- New growth remains green until severe deficiency
Fruit vs. Foliage Differences
- Fruits show no direct symptoms unlike calcium issues
- Tomatoes develop normally even with severe leaf chlorosis
- Yield reduction occurs indirectly through photosynthesis loss
- Blossom end rot only appears with magnesium-induced calcium lockout
Examine the texture of leaves during inspection. The leaves of magnesium-deficient plants are thin and papery. They feel brittle as compared to the normal foliage. I bend the suspicious leaves gently, noticing the greater fragility. This test readily checks the correctness of the visual construction of the condition in question. Always check several leaves on each plant to ensure accuracy.
Photograph symptom progression weekly. Early stage shows faint yellow patches. Mid-stage produces vibrant marbling patterns. Late stage reveals brown, dead tissue. I maintain photographic logs for comparisons. This documentation is invaluable for accurately tracking the effectiveness of treatments over time.
Eliminate similar problems. Iron deficiency causes interveinal chlorosis, primarily affecting younger leaves. Virus diseases exhibit mottling, but also include leaf distortion. I use hand lenses to detect small pests or signs of diseases. Accurate diagnosis prevents useless treatments.
Acting fast on early signals. Yellow patterns mean active magnesium loss is occurring. Waiting allows for irreversible leaf loss. As soon as I see the first visible symptoms, my response is treatment for the plant. This proactive action sustains photosynthesis, which preserves fruit development consistently.
Read the full article: Magnesium Deficiency Tomatoes: Complete Grower Guide
