Any idea about this symptom on Oleander? Alternaria alternata was isolated from these symptom but in the pathogenicity test is not pathogenic on Oleander.
Is one of the most fungal pathogens in Oleander leaves and stems. In Algeria, there are one insect pest Aphis nerii, and some cases of Pseudomonas savastanoi (in nurseries)
I think the causal agent is Ascochyta heteromorpha...yellow spots may be discolouration of infected leaf parts, which eventually become necrotic spots
try to reproduce the symptoms on plants belonging to the Oleaceae family (Legustrum, Jasminum....), while Nerium oleander is an Apocynaceae species ???