Citrus greening, also known as huanglongbing (HLB), is a serious disease affecting citrus trees. It is caused by a bacterium called Candidatus Liberibacter and is spread by the Asian citrus psyllid, a small insect. Infected trees produce bitter, misshapen fruit and can eventually die, leading to significant losses for citrus growers. The disease was first identified in China in the early 20th century and has since spread to many parts of the world, including the United States. There is currently no cure for citrus greening, making prevention and management crucial for maintaining healthy citrus crops.