Did this disease originate in China?
Yes. According to Wikipedia, it was first spotted in China, in 1943.
Citrus greening, also called Huanglongbing or yellow dragon disease, is one of the more serious diseases of citrus. This bacterial disease is thought to have originated in
http://www.aphis.usda.gov/plant_health/plant_pest_info/citrus_greening/index.shtml
From the above link:
Citrus greening, also called Huanglongbing or yellow dragon disease, is one of the more serious diseases of citrus. This bacterial disease is thought to have originated in China in the early 1900s. The disease is primarily spread by two species of psyllid insects. One species, the Asian citrus pysllid, Diaphorina citri, has been present in Florida since 1998. The bacteria itself is not harmful to humans but the disease has harmed trees in Asia, Africa, the Arabian Peninsula, and Brazil. There are three strains of the bacteria, an Asian, an African version, and a recently described American strain discovered in Brazil.
The Asian strain, Candidatus Liberibacter asiaticus was found in Florida in early September, 2005.