CSLB C-27 Landscaping ContractorPlanting and LandscapingHard
A client observes significant yellowing and stunted growth on their mature citrus trees, particularly on new leaves, with veins remaining green. A soil test reveals high pH (alkaline) and abundant calcium carbonate. Which micronutrient deficiency is most likely causing these symptoms?
- ANitrogen
- BIron
- CPhosphorus
- DPotassium
Show answer & explanationAnswer & explanation
Correct answer: B. Iron
Yellowing of new leaves with green veins (interveinal chlorosis) is a classic symptom of iron deficiency. High soil pH and excessive calcium carbonate can bind iron, making it unavailable to plants, even if present in the soil. Citrus trees are particularly susceptible to iron chlorosis in alkaline soils.
Why the other options are wrong
- A. Nitrogen deficiency typically causes general yellowing of older leaves, not interveinal chlorosis on new leaves.
- C. Phosphorus deficiency often results in purplish or dark green leaves and stunted growth, but not the specific interveinal chlorosis pattern described.
- D. Potassium deficiency usually manifests as scorching or browning of leaf margins on older leaves, not interveinal chlorosis.
Iron Chlorosis
A plant condition caused by iron deficiency, characterized by yellowing leaves (chlorosis) with veins remaining green, primarily affecting new growth.
- Common in high pH (alkaline) soils.
- Iron becomes unavailable to plants.
- Often treated with chelated iron or soil acidification.
Memory trick: When 'Iron' is locked, new leaves turn 'yellow' but 'veins' stay green.