Symptoms: Older leaves are yellowing.

Diagnosis: In most trees, nitrogen deficiency begins in the older, lower leaves and expands into other leaves if deficiency becomes more severe. It is rare for a mature landscape tree to show signs of nitrogen deficiency, unless the tree is growing in soil that is extremely low in organic matter.

Solutions: Apply nitrogen fertilizer.

Symptoms: This sweetgum tree exhibits severe chlorosis and defoliation at the branch tips.

Diagnosis: The symptoms noted result from an advanced deficiency of iron.

Solutions: Apply iron fertilizer or an acid-forming amendment. (The latter will make existing iron more available to the plant.)

Symptoms: Melaleuca tree with extensive leaf chlorosis appears to be dying back.

Diagnosis: The damage is caused by an extreme iron deficiency. It results from irrigation with alkaline (high pH) water, alkaline soil, or both.

Solutions: Replace tree with one that is more tolerant to alkaline soil pH and alkaline water, such as Athel tree or Eucalyptus camendulensis.

Symptoms: Leaves of this sweetgum exhibit interveinal chlorosis.

Diagnosis: Symptom is typical of iron deficiency.

Solutions: Apply iron fertilizer or acidify water and soil (to make existing iron more available to plant). This can be accomplished by injecting acids into the water supply or by adding acids and acid-forming amendments to the soil, such as sulfuric acid and sulfur.

Symptoms: Interveinal chlorosis on mock strawberry.

Diagnosis: Iron deficiency.

Solutions: Apply iron fertilizer. If that fails, replace plant with species more tolerant of alkaline pH, such as English ivy or Boston ivy.

Symptoms: Curling of terminal leaves of pear tree.

Diagnosis: Phosphorus deficiency.

Solutions: Apply phosphorus fertilizer.

Symptoms: Chlorosis of tips of dwarf date palm in the lower branches.

Diagnosis: Magnesium deficiency.

Solutions: Apply fertilizer that contains sufficient magnesium.

Symptoms: Yellowing of leaves of Senegal date palm.

Diagnosis: Magnesium deficiency.

Solutions: Apply fertilizer that contains sufficient magnesium.

Symptoms: Yellowing of older leaves of queen palm.

Diagnosis: Potassium deficiency.

Solutions: Apply fertilizer that contains sufficient potassium.

Symptoms: Chlorotic spotting of Pindo palm.

Diagnosis: Potassium deficiency.

Solutions: Apply fertilizer that contains sufficient potassium.

Symptoms: Interveinal chlorosis of leaves on red maple.

Diagnosis: Manganese deficiency. Looks like iron deficiency, but green veins are thicker.

Solutions: Apply fertilizer that contains sufficient manganese.

Symptoms: Chlorosis and browning of growing tips on Catalina ironwood.

Diagnosis: Both iron and nitrogen deficiencies.

Solutions: Apply nitrogen and iron fertilizers or apply an acid-forming amendment.