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Florida's Iconic Palm Trees Are in Trouble

Lethal bronzing is a problem from Jacksonville to the Florida Keys
By Newser Editors and Wire Services
Posted Aug 19, 2019 7:11 AM CDT
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In this Wednesday, July 31, 2019, photo, Brian Bahder, assistant professor of entomology at the University of Florida, points to a cabbage palm tree that died from a lethal bronzing disease in Davie, Fla.   (AP Photo/Wilfredo Lee)
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(Newser) – Florida's iconic palm trees are under attack from a fatal disease that turns them to dried crisps in months, with no chance for recovery once they become ill. Spread by a rice-sized, plant-hopping insect, lethal bronzing has gone from a small infestation on Florida's Gulf Coast to a nearly statewide problem in just over a decade. Tens of thousands of palm trees have died from the bacterial disease, and the pace of its spread is increasing, adding to environmental woes of a state already struggling to save its other arboreal icon, citrus trees, from two other diseases. If nothing is done, "I don't think all the palm trees will die, but the issue we see will get a lot worse before it gets better," says Brian Bahder, an entomologist who studies insect-borne plant diseases and is a leader in the state's battle against lethal bronzing. The AP explains the situation:

  • Lethal bronzing's first Florida appearance came near Tampa in 2006, but it's now found from the Keys in the south to Jacksonville in the north.
  • The disease is transmitted solely by the haplaxius crudus, a tiny winged insect sometimes called the American palm cixiid or, generically, a treehopper. These specific treehoppers (there are other kinds) inject the bacteria through their saliva when feasting on the sap from a palm's leaves. Any palm cixiid that later feeds from the tree will pick up the infection and pass the bacteria to more palms.
  • Once inside a tree, the bacteria migrate to its base, multiplying until they clog the circulatory system—much like human arteries getting blocked by fat and cholesterol. The blockage makes it impossible for the tree's cells to get sufficient nutrients and sugars, starving them.
  • As an infected tree dies, its fronds and central spear leaf transform from green to a tell-tale shade of bronze as it succumbs in about six months. The disease doesn't infect humans or animals.
  • Genetic testing shows lethal bronzing likely originated in Mexico's Yucatan region. Bahder's hypothesis is that 2005's Hurricane Wilma, which tracked from the Yucatan to Florida, or a storm with a similar path carried infected treehoppers across the gulf to Tampa.
  • Some worry lethal bronzing will migrate to California and Arizona, infecting date palms and damaging that fruit crop. The disease has already heavily damaged Jamaica's coconut plantations, and Brazil is taking preventive measures to avoid invasion.
  • The problem is much bigger than this treehopper. The Guardian reports some 450 pests "that damage or feed on trees" have entered the US from foreign shores, with new research indicating 40% of our forests are vulnerable to them.
(Read more palm tree stories.)

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