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Fusarium Decline of Queen
Palms
and Mexican Fan Palms in Florida
Monica L. Elliott Ph.D. Extension
Palm Pathologist
See photo examples here
The new disease of queen palms (Syagrus
romanzoffiana) that appeared in Central Florida landscapes in 2004
has now been tentatively identified as fusarium oxysparum and now
is being called "Fusarium decline". A second host has been
identified, Washingtonia robusta (Mexican fan palm). While the
disease is still primarily observed in landscapes, container and
field nurseries are also now documented as disease sites. The
problem has always appeared to be a disease. No insects are
observed in association with the palms nor are nutritional
deficiencies implicated n the problem.
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This is a quick killing disease of queen and
Mexican fan palms.
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The disease has been observed in landscapes, a
container nursery and a field nursery.
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This disease has been documented in the Orlando
area.
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Infected palms die quickly, often within a few
months of the initial symptoms.
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There is no cure once a palm is infected.
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No preventive fungicide treatments are
recommended.
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The disease is probably spread by wind into new
sites.
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Once established, it could also be spread by
pruning tools.
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Pruning tools should be sterilized after each
palm is trimmed.
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Palms, especially, queen palms and Mexican fan
palms, should not be replanted into a site where a palm with this
disease was removed.
Symptoms on queen palms
The oldest leaves turn brown but do not break
or hand down. The next youngest leaves in the canopy will turn
varying shades of yellow. Eventually, the entire canopy turns
brown. It looks as if the canopy has been freeze-dried in place.
The symptoms are different from a potassium deficiency, where the
leaflets will be brown but the petiola will be green. With the new
disease, both the leaflets and the petiole are brown. There is a
brownish-red stripe on the leaf petiole at the point where it is
bending out of the canopy. The petiole is not oft and rotted, but
simply discolored. Cross-sections through the petiole reveal
internal discoloration. Leaves may exhibit one-sided death
symptoms. Where the leaflets on one side of the leaf are brown but
the leaflets on the other side are green. With the brownish-red
stripe on the petiole corresponding to the side with the dead
leaflets.
Symptoms on Mexican fan palm
Symptoms on Mexican fan palms will also have
more brown lower leaves and younger leaves that are partly green
and partly yellow or brown. The petioles of these leaves will have
a brown to reddish-brown stripe. Cross-sections through the striped
petiole may have an internal discoloration. The individual leaf
symptoms can look the same as the petiole blight, another disease
of Mexican fan palms, but petiole blight is not normally a fatal
disease, whereas Fusarium decline is fatal.
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