By Jane Morse, University of Florida/IFAS Extension Agent in Pinellas County
What is it? Like a cancer spreading through the body, this citrus disease is spreading through Florida. This new disease is known as citrus greening or Huanglongbing and it is one of the most serious citrus diseases because there is no cure. It is caused by a bacteria that infects the vascular system of plants causing citrus trees to produce bitter, inedible fruit and die.
How is it spread? Citrus greening is spread by an insect called a psyllid. The Asian citrus psyllid, which spreads the disease, was first found in Florida in 1998. It wasn’t until 2005 that the disease was first identified in the U.S. in South Florida. This disease affects all citrus varieties and causes rapid decline of trees. Once infected, mature trees decline and stop producing fruit while infected young trees never produce fruit. In China, the disease reportedly kills young trees in 1-2 years. It can also be spread by grafting with infected wood or buds.
What are the symptoms? Early symptoms are leaf yellowing that appears on a single shoot or branch. Leaves may have a mottled or blotchy appearance during the early stage of infection. As the infection progresses, affected trees will show twig dieback and they will rapidly decline becoming non-productive within 2-3 years time. Trees with advanced disease have leaves that are small and frequently show nutritional deficiency symptoms. Fruit are sparse, small, lopsided and bitter tasting. Trees in home plantings can often be in poor condition from many other causes which can make detection of this disease difficult.
What if my tree is infected? If your tree is infected with citrus greening, it is best that you destroy the tree before it infects other citrus in the area. Remember that the tree will stop producing edible fruit and die anyway. It is important to remove the source of infection (tree) immediately because once the psyllid insect (which feeds on the tree and picks up the disease) is infected it will keep transmitting the disease to new trees for its entire life. Although there is no cure for this disease, the spread of the disease can be slowed by removing infected trees.
Are there any other plants that harbor this disease? The citrus greening disease also breeds in Chinese box orange (Severinia buxifolia), orange jasmine (Murraya paniculata) and curry leaf (Murraya koenigii), so removal of these plants will also help to slow the spread of this disease.
What can I do? You can help by purchasing only certified citrus plants from registered nurseries. Be alert and look for signs of the disease or any unusual pests. Report these to your local Extension Service at 727-582-2100 or the Florida Department of Agriculture and Consumer Services (FDACS) toll-free help line at 800-282-5153. These sources can help you with information about proper care of citrus and also provide information about citrus greening. Remember not to bring any plants, fruits, vegetables or illegal animals into Florida as they may harbor new pests. Also, consider planting fruit trees other than citrus. You play an important part in protecting Florida’s natural environment and plant life.
For more information Google: citrus greening pest alert, or call either of the help lines listed above. To see maps showing locations of positive citrus greening samples Google: citrus greening detection maps.
Information for this article came from UF/IFAS publication “Citrus Diseases Exotic to Florida: Huanglongbing (Citrus Greening)” and DPI brochure “Huanglongbing – Citrus Greening”.