Fe deficiency in Hydrangea

Fe deficiency in Hydrangea

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Scientific Name
Iron (Fe)
Atomic Number
26
Atomic Weight u
55.845
Elemental Group
Micro elements (B, Cl, Cu, Fe, Mn, Mo, Ni, Zn) | Micronutrients
Available Forms

Available forms of Iron (Fe) for use in Container Nursery Stock

  • Ferrous sulfate (FeSO₄·7Hâ‚‚O, 'Iron sulfate') – soluble, quick corrective; used in foliar sprays and drenches.
  • Ferric sulfate (Feâ‚‚(SOâ‚„)₃, 'Iron(III) sulfate') – soluble, strong acidifying effect; less common but effective in some media drenches.
  • Iron chelate (Fe-EDDHA, 'EDDHA-Fe') – highly stable, effective up to pH 9; best for high-pH container media.
  • Iron chelate (Fe-DTPA, 'DTPA-Fe') – stable up to about pH 7; widely used in fertigation for container crops.
  • Iron chelate (Fe-EDTA, 'EDTA-Fe') – economical, but only effective at low pH (≤6).
  • Iron citrate (C₆Hâ‚…FeO₇, 'Ferric citrate') – soluble organic form; sometimes used in foliar applications.
  • Iron lignosulfonate (varied formula, 'Iron lignosulfonate') – chelated with organic acids; used as soil or media amendment.
  • Iron frits (varied composition, 'Slow-release Fe frits') – glass-fused carriers providing slow, controlled Fe release in container mixes.

Iron (Fe) Deficiency in Hydrangea (Container Nursery Stock)

Symptoms

  • Interveinal chlorosis – young leaves turn pale yellow to almost white, while the veins remain distinctly green.
  • In severe cases, the entire leaf may become almost white, leading to weak growth.
  • Reduced shoot extension and smaller leaves compared to healthy plants.
  • Prolonged deficiency may result in necrotic leaf margins and tip burn.
  • Flower quality may be reduced, with weaker stems and fewer blooms.

Causes

  • High substrate pH (>6.0) is the most common cause, reducing Fe solubility and plant uptake.
  • Use of alkaline irrigation water with high bicarbonate levels.
  • Over-liming of container mixes or growing media with excess calcium carbonate/dolomite.
  • Excess phosphorus (P) fertilization, which antagonizes Fe uptake.
  • High levels of manganese (Mn), copper (Cu), or zinc (Zn), which can compete with Fe absorption.
  • Low root activity due to poor aeration, waterlogging, or root disease (e.g., Phytophthora, Pythium).

Correction

  • Immediate intervention: Apply foliar sprays of soluble iron sources such as:
  • Iron chelates (Fe-EDDHA, Fe-DTPA, Fe-EDDHA most effective in high pH media).
  • Iron sulfate (FeSOâ‚„) at low concentrations (with care to avoid leaf burn).
  • Media adjustment: Lower substrate pH to 5.0–5.5 to improve Fe availability.
  • Use acidifying fertilizers (e.g., ammonium sulfate, urea) instead of nitrate-based sources.
  • Acidify irrigation water if bicarbonate levels are high (e.g., with sulfuric or phosphoric acid injection).

Prevention

  • Maintain container media pH between 5.0–5.5 for optimal Hydrangea growth and Fe availability.
  • Monitor irrigation water alkalinity regularly; correct high bicarbonates with acid injection if necessary.
  • Use Fe-chelated fertilizers (EDDHA or DTPA) incorporated into fertigation for ongoing supply.
  • Avoid excessive phosphorus fertilization, as this ties up Fe in the media.
  • Ensure good root health with proper drainage, aeration, and disease management.
  • Regular leaf tissue analysis and substrate testing to detect early signs of nutrient imbalance.

Fe deficiency in Hydrangea

Scientific Name
Iron (Fe)
Atomic Number
26
Atomic Weight u
55.845
Elemental Group
Micro elements (B, Cl, Cu, Fe, Mn, Mo, Ni, Zn) | Micronutrients
Available Forms

Available forms of Iron (Fe) for use in Container Nursery Stock

  • Ferrous sulfate (FeSO₄·7Hâ‚‚O, 'Iron sulfate') – soluble, quick corrective; used in foliar sprays and drenches.
  • Ferric sulfate (Feâ‚‚(SOâ‚„)₃, 'Iron(III) sulfate') – soluble, strong acidifying effect; less common but effective in some media drenches.
  • Iron chelate (Fe-EDDHA, 'EDDHA-Fe') – highly stable, effective up to pH 9; best for high-pH container media.
  • Iron chelate (Fe-DTPA, 'DTPA-Fe') – stable up to about pH 7; widely used in fertigation for container crops.
  • Iron chelate (Fe-EDTA, 'EDTA-Fe') – economical, but only effective at low pH (≤6).
  • Iron citrate (C₆Hâ‚…FeO₇, 'Ferric citrate') – soluble organic form; sometimes used in foliar applications.
  • Iron lignosulfonate (varied formula, 'Iron lignosulfonate') – chelated with organic acids; used as soil or media amendment.
  • Iron frits (varied composition, 'Slow-release Fe frits') – glass-fused carriers providing slow, controlled Fe release in container mixes.
Fe deficiency in Hydrangea

Iron (Fe) Deficiency in Hydrangea (Container Nursery Stock)

Symptoms

  • Interveinal chlorosis – young leaves turn pale yellow to almost white, while the veins remain distinctly green.
  • In severe cases, the entire leaf may become almost white, leading to weak growth.
  • Reduced shoot extension and smaller leaves compared to healthy plants.
  • Prolonged deficiency may result in necrotic leaf margins and tip burn.
  • Flower quality may be reduced, with weaker stems and fewer blooms.

Causes

  • High substrate pH (>6.0) is the most common cause, reducing Fe solubility and plant uptake.
  • Use of alkaline irrigation water with high bicarbonate levels.
  • Over-liming of container mixes or growing media with excess calcium carbonate/dolomite.
  • Excess phosphorus (P) fertilization, which antagonizes Fe uptake.
  • High levels of manganese (Mn), copper (Cu), or zinc (Zn), which can compete with Fe absorption.
  • Low root activity due to poor aeration, waterlogging, or root disease (e.g., Phytophthora, Pythium).

Correction

  • Immediate intervention: Apply foliar sprays of soluble iron sources such as:
  • Iron chelates (Fe-EDDHA, Fe-DTPA, Fe-EDDHA most effective in high pH media).
  • Iron sulfate (FeSOâ‚„) at low concentrations (with care to avoid leaf burn).
  • Media adjustment: Lower substrate pH to 5.0–5.5 to improve Fe availability.
  • Use acidifying fertilizers (e.g., ammonium sulfate, urea) instead of nitrate-based sources.
  • Acidify irrigation water if bicarbonate levels are high (e.g., with sulfuric or phosphoric acid injection).

Prevention

  • Maintain container media pH between 5.0–5.5 for optimal Hydrangea growth and Fe availability.
  • Monitor irrigation water alkalinity regularly; correct high bicarbonates with acid injection if necessary.
  • Use Fe-chelated fertilizers (EDDHA or DTPA) incorporated into fertigation for ongoing supply.
  • Avoid excessive phosphorus fertilization, as this ties up Fe in the media.
  • Ensure good root health with proper drainage, aeration, and disease management.
  • Regular leaf tissue analysis and substrate testing to detect early signs of nutrient imbalance.