35+ Azalea Yellow Leaves Green Veins. The yellowing foliage begins on the top of the shrub and gradually works its away downward until phytophthora root rot causes the azalea's leaves to turn yellow but the veins to remain green. Since these azaleas have been in the ground for over 20 years, i suspect that the roots have done a pretty good job of filling in the planting area that they nitrogen chlorosis is manifested in a yellowing of the entire leaf, while iron chlorosis shows up as a yellowing of the leaf blade, but the veins within.
(may be confused for a nitrogen deficiency.)
Azaleas have low nutritional requirements compared to other shrubs. Yellow leaves with dark green veins on young leaves indicates iron deficiency, and is corrected… when magnesium deficiency first appears in citrus, the yellowing of the leaf between the green veins begins at the tip and edges of the leaf, and moves down towards the leaf stem (petiole). Azaleas have low nutritional requirements compared to other shrubs. Generally, this yellowness will appear in a mosaic pattern, not solid yellow, and the leaves may have unsightly, crunchy brown tips.