Citrus Greening Disease

Recently Soidog 2 alerted me to a disease of citrus trees that I had not previously been aware of. It's called Huang Long Bing (HLB) or "citrus greening". It is a bacterial disease that is spread by an insect called Asian citrus psyllid. A psyllid is a small sucking insect something like an aphid. When it feeds on infected trees and then flys to others it can transmit the bacteria that is the primary pathogen.

There is no cure, although injection of antibiotics is being researched. The best prevention is to control the insect vector and to inspect your trees regularly and cull infected trees. The disease shows signs initially (leaf discoloration, mottling) that could be confused with certain nutrient deficiencies. The only definitive diagnosis is by DNA-PCR lab analysis.

Chiang Mai University plant pathology department is up on this disease and that is where I took some samples for the DNA work.

This disease is only one of the many problems that citrus can get, but it is a very serious killer and is confirmed as present in the citrus orchards of northern Thailand. I share here what I have learned with the help of Soidog2's links to Florida based research and other sources. I'm posting a couple of articles that I think have the best overview and pictures, but there is much more available on the web. don

AsianCitrusPsyllid.pdf

APSnet_Feature_Citrus_Huanglongbing_The_Pathogen_and_Its_Impact.pdf