Since being found in Florida just a little more than a year and a half ago, citrus greening disease, which originated in China a century ago, has spread from 8 to 23 counties. The disease, called Huanglongbing (yellow shoot) in Asia, is spread by the bacterium Candidatus Liberibacter asiaticus (CLas) via insects.
Once citrus trees are infected, the fruit yield, rate, and quality are greatly reduced. The trees also become susceptible to other diseases and health problems. In some areas of Brazil, citrus greening has affected as much as 70 percent of the fruit rate and yield. Since Florida has nearly $10 billion in citrus products, it is important to avoid spread. However, right now citrus greening disease can only be managed, not completely controlled.
Obviously pesticides that reduce the Asian citrus psyllid insect population are beneficial to reducing spread but environmental groups strongly object to effective pest control. That leaves antibiotics, but the bacterium attacks the vascular tissue, called the phloem in the innermost layer of bark, which is responsible for transporting sugars to developing roots and fruits. Bitter, green, inedible fruits result, and once they appear - citrus greening affects all types of citrus species - it causes infected trees to yellow, decline, and possibly die within a few years of infection.. Because it is in the innermost layer, antibiotics are less effective.
In California, researchers are continually looking for evidence of the citrus psyllid. If it is found there, citrus trees will need to be closely monitored for disease symptoms. Growers are urged to become familiar with the symptoms of huanglongbing, to scout for the symptoms and to send in samples for testing.
Citrus Greening Disease Continues To Spread