Texas Phoenix Palm Decline
In 2006, a deadly disease was found in the Tampa/Sarasota area attacking Phoenix spp. (date palms). In 2008, cabbage palms, Sabal palmetto, the Florida state tree became infected. It is now found in all of west-central Florida.
The organism was identified as a phytoplasma (bacteria without a cell wall), similar to what caused the outbreak of "lethal yellowing" in the 1970s that practically eliminated coconut palms from the Florida landscape.
The new disease is named Texas Phoenix Palm Decline (TPPD) because it was originally described in southern Texas on Canary Island date palms, Phoenix canariensis. It is thought to moved from tree to tree by tiny sucking insects, such as leaf hoppers as was the case with lethal yellowing.
Along with attacking Canary Island date and cabbage palms, it is also attacking many Phoenix palms including the true date, Phoenix dactylifera, the wild date, Phoenix sylvestris, and the Senegal date, Phoenix reclinata.
Symptoms of disease
So what should you be looking for?
>> Earliest symptoms start with discoloration of the oldest (lowest) leaves beginning at the leaflet tips.
>> Subsequently, the flower/fruit stalks die, dropping all of the flowers and fruits.
>> With Phoenix species, death of the spear leaf (new unfolding leaf) follows. This may not necessarily be the case with Sabal's.
Fortunately, if the disease is caught in its infancy, an antibiotic has been approved by the EPA for trunk injection named oxytetracycline HCL, referred to as OTC, however, it must be administered every four months for the life of the palm. The product and injection equipment are available through palmtreesaver.com or contact an ISA-certified arborist at isa-arbor.com/faca/findArborist.aspx for a diagnosis and treatment.
If you have specimen palms that are susceptible and you notice problems in your neighborhood, you might want to start a preventative treatment of OTC.
More information on the Web: edis.ifas.ufl.edu/pp163
A different disease began attacking queen palms, Syagrus romanzoffiana, the fast growing feather palm with clusters of orange edible fruit, as well as Washington, Washingtonia robusta, the 70-foot towering palm. This is caused, by a fungus and no drug is available.
Fusarium wilt of palms arrived on the scene in 2003 in south Florida on queen palms, but exploded around the state by 2007 adding Washington palm as a susceptible candidate. Unlike TPPD, which may take six months to a year or more for the palm to die, Fusarium sp. acts quickly, and will kill in two to three months.
For queen palms, with a feather-type frond, there will be at least one frond where the leaflets on one side of the rachis (midrib of the frond) are green and the other side chlorotic (shades of yellow), or more often brown showing desiccation and eventually all of the leaflets will turn brown which is very unique to this disease. The browning is progressive starting from the oldest two to three fronds moving up until the entire crown is brown with no drooping of leaves, like the canopy was freeze-dried in place.
For Washington palms, with a fan type frond there will be at least one older frond with a mixture of healthy, chlorotic and necrotic (brown, dead) segments in the leaf blade, quite colorful actually, also with a reddish-brown stripe down the rachis. As with the queen palm, the canopy turns brown rapidly from the bottom fronds up leaving a large sphere of death on a stick.
How it's spread
Unlike TPPD, Fusarium wilt is not spread by insects, but either by spores (microscopic seeds of a fungus) blown in the wind or by contaminated pruning tools. Tools, including loppers, pruning saws and chain saws should be brushed clean of debris and soaked for five to 10 minutes in one of three mixtures:
• 1 part bleach mixed with 3 parts water (25 percent)
• 1 part pine oil cleaner mixed with 3 parts water (25 percent)
• 1 part rubbing alcohol mixed with 1 part water (50 percent).
Chain saws need to be broken down, the bar and chain soaked.
Pruning of Washington and queen palms should be of dead fronds only. A tree could be newly infected showing no symptoms, so to prevent inadvertent contamination, tools need to be cleaned and soaked before moving on to the next tree.
Ask your landscape maintenance crews if they have cleaned and soaked their equipment and exactly how before they prune any fronds from your queen or Washington palms.
More information on the Web: edis.ifas.ufl.edu/pp278