By My Clay Sun

The latest in a series of devastating blows to the citrus industry is not yet known to have hurt our area. However, the insect capable of carrying it has been spotted - the Asia citrus pysllid (Diaphorina citri). I get lots of calls on this subject, hence this article.

The disease is called citrus greening, or in its Asian countries of origin, huanglongbing (HLB). This serious bacterial citrus disease is carried by the small insect mentioned, but once in the tree spreads through it branch by branch. Early symptoms of HLB are a yellowing of leaves that may occur on a single shoot or branch. The leaves are blotched yellow (not just yellow between veins) and will be easily confused with nutritional deficiencies (common in our area).

In homeowner situations it is nearly always a nutritional deficiency, so please don't become alarmed if your leaves appear with this blotched look. With this disease, frequently only one branch on the whole tree shows this symptom, not several! The Chinese name huanglongbing is loosely translated to mean "yellow dragon," which describes the stark nature of this symptom against an otherwise green tree.

As the disease progresses, the tree will have fewer fruit and the fruit will become sour. Again, I point this out not to frighten anyone with a citrus tree that is declining, because there are lots of reasons for this to happen, but to simply to alert everyone to this very serious disease not yet known in our area. Don't overact and convince yourself you have it because your tree has yellow leaves or suckers from below the graft have come out to produce sour oranges. HLB is devastating groves in South Florida, but not here.

If you have concerns, go to the new UF Web site, where there is a power point presentation on how to recognize this disease and lots of information on its spread. You will also find pictures of the Asian citrus pysllid, which you should become familiar with. We can spray against that when we see it. This website was created by the Southern Plant Diagnostic Network. To access it go to http://spdn.ifas.ufl.edu. Once there, click on "Citrus Greening."

Even if you don't have a computer, it's still necessary to access this site, so visit a friend who does or go to your local library and log on - they will help you. I won't accept "I'm too old to learn" as an excuse so don't use it if you call me. Also, don't panic and convince yourself your tree is doomed until you visit this site, and even then, chill. The chance you have HLB is low, and even if you do, there's nothing you can do about it but spray against the pysllid to protect your other trees and pick fruit from the infected tree for as long as it is still good to eat. When it is not, cut the tree down to remove it.

Raymond Zerba is a University of Florida Clay County extension faculty member. To ask a question, call 269-6355 in Orange Park, 284-6355 in Green Cove Springs and Middleburg, or 473-3711 in Keystone Heights.


Source: http://www.jacksonville.com/tu-online/stories/112307/nec_219512059.shtml