LTC 189-2010 Cold Weather Damage to the City's Trees & Palmsm MIAMIBEACH
OFFICE OF THE CITY MANAGER
No. t_TC # is9-ZOio LETT~~ ~~ ~bCNt°~11A~11~~ION
TO: Mayor Matti H. Bower and Members of the City Comr~issiiJr~~~-E~'ti'f~'a 0~"F ~~~
FROM: Jorge M. Gonzalez, City Manager ,
DATE: July 6, 2010
SUBJECT: Cold Weather Damage to The City Trees and Palms
This Letterto Commission is intended to inform you regarding our efforts to address the impactof lastwinter's
extended cold spell on many of Miami Beach's sub-tropical trees and palms. As you may have noticed, many
of our trees suffered cold damage, as evidenced by leafless branches and dead fronds. According to weather
reports, the cold spell that damaged the city's trees was South Florida's longest period of cold weather in forty
years. While owners of citrus orchards and agricultural fields attempt to protect trees and crops by misting and
smudge pots, unfortunately, such methods are not practicable in urban environments/city street trees. Since
the cold damage first appeared, the Park Department's Greenspace Management Division has been closely
monitoring the damaged trees.
Especially noticeable is the damage to the mature calophyllum trees lining Meridian Avenue, which dropped
many of their leaves and have many bare, dead-looking branches. Although the trees may not look good,
based on our preliminary assessment it is too soon to assume they are damaged beyond recovery and start
trimming. Tree branches that appear dead after defoliation often recover and produce new buds and leaves.
Experts advise waiting two to six months before trimming to first understand the full extent of the damage.
The Greenspace Management Division recently used a bucket truck to evaluate impacted trees, including
branches in the crowns of several calophyllum trees. The trees are now activating dormant buds under the
bark to produce new. shoots. On Meridian Avenue, this process can be seen in the small clusters of new
shoots that have been appearing during the past few weeks, scattered through leafless sections of the crowns
of the calophyllum trees. The trees' response is similar to that of a hatracked tree that needs to produce a
whole new set of branches after being trimmed; this process takes longer than simply leafing out from existing
buds, and as long as the branches are not dead, they should produce new shoots and leaves. The Division's
recommendation is to give the trees at least a full growing season to recover and show the full extent of
damage before scheduling any trimming to avoid removing good branches that might recover if given a little
more time. The Division is also fertilizing the trees on Meridian Avenue to provide the nutrients they need to
produce new growth. While they should restore some or much of their crowns, it is not expected that they will
be totally back to normal this year.
Many of the city's palms also experienced cold damage, mainly brown, hanging fronds. Afterthe cold damage
appeared, the decision was made to leave the dead fronds on the palms until the threat of additional cold
spells ended because the dead fronds provide some insulating protection to the palm's apical bud; the apical
bud produces all of a palm's fronds and if the bud dies, the palm dies. Damage to coconut palms was
widespread in the city, but most are expected to recover. When the threat of cold weather ended, trimming of
dead fronds started, and still continues. Additionally, the apical buds of the blue latan palms were treated with
a fungicide to reduce the risk of bud rot induced by cold damage. A number of coconut palms scattered
around the city have died, apparently from the effects of cold, but palm experts are unsure of the exact reason;
the deaths do not seem to be associated with bud rot. The city's palms are now starting to produce new
fronds, but some fronds might have been damaged by the cold while they were developing in the apical bud
and may be severely deformed when they emerge. Subsequent fronds are expected to improve in quality.
We will continue to monitor.~As always, please feel free to contact my office should you have questions.
JMG/HMF/KS/CL H:\Parks\Greenspace\LTC_Cold Damage 6-30-10.doc