With citrus leprosis a re-emerging threat to citrus, know the details of the disease.


Citrus leprosis was once a disease that ravaged the citrus industry in Florida and elsewhere, but it mysteriously disappeared in the 1960s, according to an article on CitruIndustry.net. Called “nailhead rust,” the disease created necrotic spots or lesions on a citrus tree’s leaves, twigs, and fruit. While it’s speculated that the disease disappeared because a deep freeze in 1963 killed the mites that spread citrus leprosis, it’s a fact that the disease has been located in three places in Mexico and one in Texas. Know the details of citrus leprosis.

Citrus Leprosis Details


Here are some facts about the disease as shared in the Citrus Industry article.

  • Appearance: “On symptomatic fruit, the spots are usually brown, reddish-brown or tan-colored. The lesions on fruit are limited to the fruit rind only and do not extend into the fruit sections.” And “The symptoms of leprosis are distinctive; however, they could be confused with citrus canker lesions on leaves, fruit and twigs.” Testing confirms the disease.
  • Impact: “Left untreated, leprosis disease will kill a mature citrus tree in about four years. Leprosis affects all citrus types (sweet orange, mandarin, lemon, grapefruit and citranges) as well as Swinglea glutinosa, a citrus relative.”
  • Transmission: “The disease is spread by Brevipalpus mites, commonly called broad mites. The Brevipalpus mites have a broad host range with over 900 plant hosts reported from 513 genera.”
  • Treatment: “Mite control is essential for the control of leprosis. In Brazil, where leprosis has been endemic for many years, 12 or more miticide applications are made yearly. Leprosis-infected trees can be recovered with the pruning of the symptomatic branches, followed by good mite control, but the pruning of individual trees is expensive.”

The article’s author, Richard F. Lee, a professor of plant pathology at UF/IFAS CREC and supervisory research plant pathologist at the USDA’s Agricultural Research Service National Clonal Germplasm Repository for Citrus and Dates, shared: “Early detection of leprosis disease would provide the opportunity for eradication or at least suppression of the infection to keep it from becoming widespread in Florida.”

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