Lethal yellowing is hitting more types of coconuts, and screwpines are
Doug Caldwell - Collier County Extension Service
Saturday, January 20, 2007
Now that more people (including homeowner association board members)
are back, I am repeating information on palm lethal yellowing disease
that was in the August column. It is important to be aware that there
are no coconut varieties that are resistant to this disease.
Researchers reported in 2002 that more than 70 percent of the
so-called resistant 'Malayan' and 'Maypan' coconut palms died of palm
lethal yellowing disease in the Fort Lauderdale research plots. If you
plant a coconut in our area, I would strongly suggest that antibiotic
inoculations be part of its routine maintenance, as much if not more
so, than watering and fertilizing.
As of last week, we were alerted to dying coconuts and Christmas palms
on Outrigger Lane, North Alhambra Circle and Kent Drive These have
been removed and inoculations of nearby palms started by the county.
Another outbreak started in October, 2005, in the area between High
Point Drive and Solana Road. The county suppression program, per
Ordinance 2004-11, has funded the removal of infected palms and
initiated 100-yard-radius inoculation zones around the palms that were
There are currently seven active areas, besides the area just
mentioned, we have suppression programs in:
� Poinciana Village and Coco Lakes
� Naples Park (94th to 102nd avenues)
� Lakewood Villas
� Henderson Creek & Collier Boulevard (County Road 951)
� Isles of Capri
� Kent Drive area south of Kings Lake
The county is currently inoculating about 1,046 coconut, Christmas and
Canary Island date palms three times a year. The inoculations, 5 cc
per coconut, are an antibiotic (oxytetracyline) labeled for use on
palms. The antibiotic suppresses, but does not eradicate, the disease
Citizens are not required to pay for the removals nor the
inoculations. Remaining stumps are not "ground out" as they pose no
threat in the spread of the disease.
Please report suspicious palms � of susceptible species only � that
are in the county, but outside of the city limits, to me. If palms are
inside the city limits, call Joe Boscaglia, 213-7123. Please report
suspect palm lethal yellowing-infected palms on Marco Island to the
environmental specialist, Nancy Richie, 389-5003.
We have also hired a scout to more closely monitor the "hot spots"
four times a year in a grid-like fashion, street by street.
As part of the suppression program, the county will remove a dying,
diseased palm, if it is caught early and still has some green fronds.
Palm lethal yellowing disease is spread by a planthopper, a
3/16-inch-long insect. The disease-causing organism that the
planthopper injects into the plant as it feeds is a "wall-less"
prokaryote (phytoplasma). The phytoplasma flourish inside the palm and
plug up the vascular system. Palms die rapidly, within five to seven
If no green remains in the fronds, the little planthopper won't feed
on the palm nor be able to spread the disease. Thus, the palm is not a
threat if it has died.
Please don't report a palm if it is a queen, royal or cabbage palm, as
this is one disease these species and other native palms do not get.
Also, Washingtonia, areca, Alexandra, Carpentaria, Ptychosperma,
foxtail and pygmy date palms have not been reported to succumb to this
However, the disease has been reported to attack 38 other species of
palms and screwpine (Pandanus spp.). There are no resistant coconut
varieties, other than a very slow growing and unavailable 'Fiji Dwarf'
coconut. To avoid bringing infected palms into our county, it is
advised NOT to purchase palms grown east of the Collier County line.
There is less incidence of palm lethal yellowing disease in palm
nurseries in the Gulf Coast areas. Other areas have severe problems
with this disease and importing palms from infected areas has caused
large losses of palms in Collier County.
Fortunately, this disease is not spread mechanically on pruning equipment.
Symptoms vary with the coconut cultivar and palm species. If the
coconut palm still has fruit, I don't usually consider it a high
probability of being infected. Usually two of these symptoms are a
strong indication of an infected palm:
Coconut palms: Fruit drop and the stem-end is blackened and water soaked.
Coconut palms: flower tips emerge chocolate brown and droop instead of
being held upright. 'Jamaican Tall' coconut: third or fourth new leaf
turns yellow; oldest fronds drop parallel to trunk; no leaf wilt
symptoms. 'Malayan' or 'Maypan' coconut: wilt symptoms only, with
individual leaflets wilted and folded up; mid-canopy fronds turn brown
and droop; there is no yellowing.
Christmas palm: similar to Jamaican Tall, but without yellowing;
oldest leaves may bronze.
Pritchardia (Thurston and Fiji fan palms): death of spear leaf is
For pictures of LY symptoms, information on sending samples for
laboratory analysis and inoculators that are using currently approved
methods, see this Web site:
Or call us. The Extension Office landscape horticulture specialist
will present a brief photo show on the history and recognizing
symptoms of the disease followed by a question and answer session at
the Collier County Public Library Central Avenue branch next Saturday,
Jan. 27, from 10 to 11:30 a.m.
Doug Caldwell, Ph.D., is the commercial landscape horticulture
extension agent and landscape entomologist with the University of
Florida Collier County Extension Service. E-mail firstname.lastname@example.org
Call 353-4244 x203 or visit: collier.ifas.ufl.edu
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