Lilac Iron Chlorosis: Yellow Leaves with Green Veins in Alkaline Soil

Old lilac has yellow leaves with green centers/veins. Others nearby (new) unaffected. Disease or malnutrition?

Diagnosis: Iron Chlorosis

High soil pH (alkaline) locks up iron. Symptoms: interveinal yellowing, progressing to brown scorch.

Fix

1. Soil test (mixed samples)
2. Amend per lab (sulfur, iron chelate)
3. Early spring: Iron chelate at roots
4. Summer: Foliar chelated iron spray (cool part of day)

Aggravating Factors

• Heavy soil, overwatering, high phosphorus