Citrus stubborn disease is one of the most important diseases affecting citrus trees in the world. My research work experience in the Mediterranean Agronomic Institute was very fruitful, it was concerning an important serious disease affecting citrus trees in the Mediterranean region which is citrus stubborn disease, my work in the detection ended up by setting up of efficient protocols for the detection and diagnosis of the causal agent of this disease, which is considered as a turning point in the study of the epidemiology of such disease and will facilitate and improve the surveys and the certification programs of citrus in the Mediterranean region. this work also helped for the detection of the causal agent in Italy for the first time which is the first report of this important disease in Italy.