Citrus is a fruit tree with high economic value. However, pests and diseases are one of the factors that hinder the development and increase production costs. One of the most dangerous diseases on citrus is greasy spot disease. Greasy spot disease is common on citrus grown in tropical and subtropical regions. The disease affects the growth and development of plants, affects yield, quality and reduces commercial value. In our country, citrus greasy spot disease is also often harmful, especially in the Mekong River Delta, however, so far it has not been noticed.