City Trees

36 CityTREES I have spent most of my life in South Florida, and I grew up among vast numbers of coco- nut and royal palms (Cocos nucifera and Roystonea regia). To me, there is no plant that conjures up the tropics and subtropics better than a large healthy palm. In my travels throughout the world as a con- sulting arborist, I look forward to seeing new and unique specimen palms. As a teenager, I witnessed the loss of hundreds of thousands of coconut palms due to lethal yellowing as this disease entered the Florida Keys and spread throughout South Florida. It was stunning to visit our public beaches and suddenly see no palms where once there had been thousands! When I first began working at Parrot Jungle, a private- ly owned zoological theme park with a strong horti- cultural ethic, I began as the assistant horticulturist to Nat Deleon, a former president of the Palm Society who started the Society's seed bank. The Park had a large collection of rare palm species, and there was a 20-acre (8 ha) palm nursery adjacent to the property where large specimens were sold out of the field. In my formative years as a horticulturist I quickly became aware of issues that could affect the health of palms. I remember being directed to test various chemical concoctions against lethal yellowing of coconut palm (none panned out). Now I am keenly aware of palm diseases and how quickly they can dec- imate a single species or population. I am also aware of fruit or palm fronds that can drop out of the palm canopy and cause damage. My work as a horticulturist and facilities manager at three theme parks for almost 40 years made me acutely aware of these issues. Not only did the park and its palms need to look good, we had to protect our patrons, staff, and animal inhabi- tants from potential injury. I remember planting small royal palms in a public area knowing that once they got too tall and we could no longer physically remove the senescing fronds and crown shafts, I would eventually have to direct the removal of the palms. (Crown shafts are the overlap- ping, sheathing leaf bases between the palm trunk and the canopy.) As a consultant I have been involved with several cases of people being injured by falling crown shafts of royal palms. Many facilities now zip- tie the crown shafts onto the royal palms (see pic) to be removed by hand instead of allowing them to drop. Another potential hazard is falling coconuts from the coconut palm. While I've not met someone person- ally who was injured, I do know of car windshields and clay roof tiles that have been smashed by falling coconuts. That arborists should wear helmets when working on any tree, but perhaps especially a coconut palm, is obvious. My first encounter years ago with the fruit of Caryota mitis, the fishtail palm, was somewhat painful. The ripe fruit can be quite caustic and a single inflores- cence can produce hundreds of fruit. I now know not to plant these palms near an area the public has access to or where they would pass underneath, yet I often see these palms installed near public areas. While this palm is great for screening properties and buildings, you don't want it in any area where children might pick up the fallen fruits. An issue I am confronting with increasing frequency is the failure of an entire palm due to basal stem rot caused by Ganoderma zonatum, a virulent fungal pathogen that affects only palms. At some sites I visit, I find this fungus to be epidemic and occurring on many species. This fungus enters palms through wounds where trunks were removed from multi-trunk- ed species or where trunks were damaged by equip- ment. Replacing dead or dying palms in places with a history of this fungus is not recommended because fungal spores remain in the soil. Many palms diseases have been shown to be transmis- sible by infected pruning tools. I always inquire with property managers if they have written into their land- scape maintenance contracts that pruning tools have to be sterilized before pruning is conducted on the site's palms. They often seem surprised and wonder what the extra cost will be. When I am working with architects from municipalities or the private sector, I always bring up disinfecting tools and encourage them to write this into the maintenance specifications. Recently I was called in to inspect a newly installed landscape that included palms. All of the stakes— which had been attached with nails—had been removed from the palms. Some of the nail holes had begun to ooze a black slime—really bad news! This project had been done by a large, well-established landscape contractor. If these folks don't know not to nail holes into the trunks of palms, who does? Education, education, education! We are growing so many more species of palms in South Florida now, especially since it is much warmer in the winter. This allows us to greatly enhance our tropical look. I still get a thrill when I see a beautiful palm specimen. I just hope that everyone involved in its care is aware of how to properly maintain it. —Jeff Shimonski, Consulting Arborist & Municipal Specialist, Jeff@TropicalArboriculture.com

• Cover