Explore another treatment possibility, besides drilling holes, to manage this fatal disease:
What: The feasibility of a soil-applied systemic insecticide offered by Doug Caldwell, Collier County extension agent
Where: Queens Park at 5210 Malvern Court
When: 10 a.m. on Jan. 30
Palm lethal yellowing disease eliminated thousands of coconut palms on the east coast of Florida back in the early 1970s through the early 1980’s. Tourists were dismayed when they arrived at their beach destination to find no coconut palms along the beach or only dying coconut fronds drooping in the breeze. The ambience was severely impacted.
The disease arrived in Naples in 1974 and has taken its toll, but thanks to some suppression ordinances and monitoring efforts by County and City officials, the impact hasn’t been as devastating. Please note 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 any variety of coconut in our area, I would strongly suggest that antibiotic inoculations (OTC- Oxytetracycline injected 3 to 4 times per year) be part of its routine maintenance, as much if not more so, than watering and fertilizing. The OTC inoculation dose is about 5 cc per coconut palm and the product is registered for use on palms. The antibiotic suppresses, but does not eradicate, the disease organism, so inoculations are a lifetime committment. For more information on the product and the technique see: www.palmtreesaver.com/index.htm
Early removal of infected palms is the homeowner’s responsibility as well as inoculating nearby palms which may have been infected. The County suppression program was discontinued two years ago. The City of Naples has stopped inoculating palms on private property but is looking after the coconut and Canary Island Date palms on city-owned property, which amounts to about 3,300 palms.
However there are active Naples and Marco Island ordinances which require removal of infected palms. Please report suspect infected lethal yellowing palms on Marco Island to the environmental specialist, Nancy Richie, 389-5003 and if in the city limits of Naples, call Heather Shields at 213-7136. Please do not report a palm if it is a queen or royal 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 disease.
Some hot spots for this disease include:
Outrigger Lane; North Alhambra Circle; Kent Drive; the area between High Point Drive and Solana Road; Poinciana Village and Coco Lakes; Naples Park (94th to 102nd avenues); Lakewood Villas; Henderson Creek & Collier Boulevard (County Road 951); Isles of Capri; and Kent Drive area south of Kings Lake
Much like the malaria organism is spread or vectored by a mosquito from infected to healthy individuals, 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 sometimes referred to as a “primitive” bacterium because it 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 months. 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.
However, the disease has been reported to attack 38 other species of palms as well as 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 in areas east of the Collier County line , as importing palms from infected areas has caused flare-ups of the disease and losses of palms in Collier County in the past.
There is less incidence of palm lethal yellowing disease in palm nurseries in the Gulf Coast areas. 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. 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 first symptom.
For pictures of LY symptoms, information on sending samples for laboratory analysis and inoculators that are using currently approved methods, see these Web sites: collier.ifas.ufl.edu/CommHort/LethalYellowing.shtml
Doug Caldwell is the commercial landscape horticulture extension agent and landscape entomologist with the University of Florida Collier County Extension Service. E-mail email@example.com; phone, 353-4244 x203. Extension Web site: collier.ifas.ufl.edu