Stephen H. Brown, Horticulture Agent
Lee County Extension, Fort Myers, Florida
(239) 533-7513 brownsh@ufl.edu
http://lee.ifas.ufl.edu/hort/GardenHome.shtml
Lightning Strikes on Coconut and Royal Palms
South Florida has been designated by some as the lightning capital of the world. Given so many strikes,
the probability of damage to plants is very high. Coconut (Cocos nucifera) and royal palms (Roystonea
regia) are particularly susceptible due to their great height, but other tall palms are equally susceptible.
Lightning season in South Florida is generally from mid-June through September.
Heat and Speed of Lightning
The most important effect is the extreme heat, speed and shock waves generated by the bolt. The electrical current produces temperatures in excess of 50,000°F in a millionth of a second. The velocity is about
1/10 the speed of light making the trip from cloud to ground, through or around the plant and back to the
cloud in about 100 millionths of a second. A direct lightning strike on a palm is usually fatal.
Indications that Lightning has Struck a Palm
Diagnosing a lightning strike is very important as the symptoms may be confused with other causes such
as Thielaviopsis trunk rot. Lightning injury symptoms are variable and could include the following:
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Symptom onset occurs within days of recent thunderstorm.
A sudden collapse of the crown occurs, usually beginning with the older, lower fronds.
The collapsed fronds are at first green but become brown and necrotic within days or in two to three
weeks.
The crown shaft of royal palms is sometimes broken and collapsed at its base.
An upper hollowed trunk sometimes occurs in royal palms.
The hollowed trunk may at first be filled with slush from the overheated shattered tissue.
Odorless wound during the first few days of the injury and perhaps weeks thereafter.
Longitudinal gash on the trunk and/or crownshaft.
Shot holes in the trunk.
Bleeding of the trunk.
Fallen nuts.
Injury to understory plants.
Several palms can be killed by a single strike if they are in close proximity. The lightning can ricochet from one palm to the other in a grouping. If this occurs, it is possible that palms directly hit will
die very quickly, whereas the other palms are more likely to linger for months before dying.
Management
Lightning injuries are usually fatal to palms although some may survive six months or longer following
a strike. The injury cannot be treated, and prevention by mounting lightning grounds within palm canopies is impractical for all but the most valuable palms.
Dead trees and palms are a scarce resource in many urban sites. A dead palm can remain standing for
years without any fronds. If it is not a danger to pedestrians or structures, it could conceivably serve as a
“snag” to attract wildlife. It is an ideal nest site for woodpeckers and other cavity-nesting birds that cannot excavate their own nesting cavities. However, dead palms also serve as a magnets for Ganoderma
Butt rot to become established in the landscape and that is a good reason not to keep them around. If the
palm is removed, the stump should be ground-up to prevent it from becoming a food source for Ganoderma zonatum, the fungus that causes Ganoderma Butt rot.
Coconut Palms Struck by Lighting
Three coconut palms affected by lighting strike. The
effect is less pronounced from first to last palm. August
7th.
July 20th
August 8th
Continuing decline of the palms. September 3rd.
August 8th
Coconut Palms Struck by Lightning
Late July
Early September
Collapsed fronds and fallen nuts. Early October
Late July
Decline of a Royal Palm Struck by Lightning
August 10
September 1
August 22
September 1
Decline of a Royal Palm Struck by Lightning
September 25th
Longitudinal gash on trunk.
September 25th
October 6th
The damaged spear leaf is the last
to topple. October 6th
October 20th
The necrotic crown and crownshaft
will soon fall. October 20th
Symptoms of a Royal Palm on September 23rd struck by Lightning Two Days Before
Lighting struck palm with broken crownshaft is being removed from the landscape.
Fresh mush is pulled from the odorless trunk.
The damage has caused a large cavity in the upper portion of the
trunk.
The damage extends to the lower trunk but with no apparent
cavity.
Additional Indications of Palms Struck by Lightning
Collapsing crown of coconut palm.
Scorched understory hibiscus plant by struck queen
palm.
Bleeding from a coconut trunk.
References
Broschat, T.K. 2011. Physiological Disorder of Landscape Palms. University of Florida Research and
Education Center, Fort Lauderdale, Florida
Nelson, S.C. 2008. Lightning Injury to Plants. University of Hawaii Cooperative Extension Service,
Manoa, Hawaii
Zona, S. 2008. When Lightning Strikes. Growing Palms: Horticultural and Practical Advice for the Enthusiast. Palm Journal, International Palm Society
Palm Links
Bismarck Palm
Buccaneer Palm
Cabbage Palm
Cabbage Palm Pictorial
Cold Damage of Coconut Palms
Cold Damage of Christmas Palms
Diseases of Palms
Florida Native Palms Power Point
Florida Thatch Palm
Fusarium Wilt of Queen Palms
Fusarium en Palma Reina
Ganoderma Butt Rot Video
Ganoderma Butt Rot Development Video
Hurricane Palm Recovery
Identification of Palms
Nutrition and Fertilization of Palms
Palm Aphids Power Point
Palm Bagworms
Palmetto Weevils Attack Bismarck Video
Palmetto Weevils Attack Canary Island Video
Palmetto Weevil Grubs Video
Portrait Gallery
Pruning a Cabbage Palm Video
Root Initials
Some Palm Problems Power Point
Transplanting Sabal Palms
All but one pictures taken by Stephen H. Brown.
This fact sheet was reviewed by Drs. Tim Broschat and Monica Elliott, Fort Lauderdale REC; Peggy
Cruz, Lee County Extension and Connie Brennan, Lee County Master Gardener.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, religion, age, disability,
sex, sexual orientation, martial status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension
Service, University of Florida, IFAS, Florida A. & M. 9/2014.