Oleander yellow leaves: possible causes

Yellowing can be uniform or follow the central vein under drought stress. Oleander leaf scorch instead often starts at the tips or margins, beginning on one branch and spreading.

Check whether yellowing affects all branches or one part of the canopy, whether leaves droop, and whether the pattern starts at the margins or tips. Inspect both leaf surfaces and new shoots for aphids, scale, caterpillars, honeydew or sooty mold.

Yellow leaves can follow drought or other water stress, oleander leaf scorch caused by a strain of Xylella fastidiosa, salt or boron injury, and sap-feeding pests such as oleander aphid or scale. Yellowing alone does not choose among them.

Correct obvious water stress without keeping the root zone saturated and inspect leaf surfaces and new shoots for pests. If the branch pattern and progression fit suspected leaf scorch, use a qualified plant diagnostic service.

After a measured watering correction, observe whether uniformly yellow, drooping leaves recover. Continued branch-by-branch decline warrants diagnostic help. Recovery is not a stand-alone disease test.

Yellow leaves are a shared symptom, not a diagnosis. Salt or boron injury can look like leaf scorch, and telling them apart may take a soil, leaf-tissue or lab test.