Unfortunately many diseases such as Huanglongbing" (HLB), CTV, WBDL, canker and phytophtora have been threatening citrus industry in the world as well as in Malaysia. The disorder of citrus described as greening disease has caused great damage in the citrus industry and known as Huanglongbing (HLB) disease. It was detected in Malaysia since 1990 and most of the Citrus species are susceptible on HLB disease.