Citrus vein phloem degeneration

Citrus Vein Phloem Degeneration (CVPD), also known as "Citrus Greening Disease", "Yellow Shoot Disease" (translated from Chinese "huang-lunpin", also translated as Yellow Dragon Disease), "Huanglongbing", "Likubin" in Taiwan (translated from Chinese as Immediate Withering Disease), "Leaf Mottle Yellows" in the Philippines, and "Citrus Dieback" in India, is probably the worst disease of citrus caused by a vectored pathogen. The causative agent is a motile bacterium, "Candidatus" Liberibacter spp. Transmission is by Asian citrus psyllids (Sternorrhyncha: Psyllidae), also known as "Diaphorina citri" or, in Africa, by "Trioza erytreae," the African citrus psyllid, also known as the 2-spotted citrus psyllid. The disease was first described in 1929 and first reported in China in 1943. "Likubin" has seriously affected Taiwan since 1951. The African variation was first reported in 1947 in South Africa, where it is still widespread.

Distribution of CVPD is primarily in tropical and subtropical Asia. It has been reported in all citrus-growing regions in Asia except Japan. The disease has affected crops in China, Taiwan, India, Sri Lanka, Malaysia, Indonesia, Myanmar, Sri Lanka, the Philippines, Pakistan, Thailand, the Ryukyu Islands, Nepal, Réunion, Mauritius, and Afghanistan. Areas outside Asia have also reported the disease: Saudi Arabia, Brazil and, since 1998, Florida in the U.S..

This disease is distinguished by the common symptoms of yellowing of the veins and adjacent tissues; followed by yellowing or mottling of the entire leaf; followed by premature defoliation, dieback of twigs, decay of feeder rootlets and lateral roots, and decline in vigor; and followed by, ultimately, the death of the entire plant. Affected trees have stunted growth, bear multiple off-season flowers (most of which fall off), and produce small, irregularly-shaped fruit with a thick, pale peel that remains green at the bottom. Fruit from these trees tastes bitter. [http://www.fftc.agnet.org/library/article/tn2001002.html]

External links

* [http://creatures.ifas.ufl.edu/citrus/acpsyllid.htm Asian citrus psyllid] on the UF / IFAS Featured Creatures Web site