Climate Change and Tropical Fruits in South Florida

This is the article I wrote for this months RFVC of Broward County newsletter.

I’m not a climatologist or a meteorologist, but it doesn’t take one to realize it is getting warmer. Especially if you were born here or have lived here thirty or more years like me. How will this affect a rare fruit grower you ask? Well, we know that Cherimoya (Annona cherimola) and Pineapple Guava (Feijoa sellowiana) prefer a more temperate climate. Could our beloved Lychee (Litchi chinensis), Longan (Dimocarpus longan) and Mango (Mangifera indica) trees range further north. Could fruits like Rambutan (Nephelium lappaceum), Mangosteen (Garcinia mangostana) and Durian (Durio zibethinus) eventually grow in South Florida? Unfortunately, most of the real good research was done in the 50’s and 60’s and most of today’s books and websites that claim to be authorities only regurgitate information from the one good source. “Fruits of Warm Climates” Julia F. Morton (1987) All of the “experts” say it can’t be done. I say more research is needed. Mr. Bill Whitman grew and fruited Mangosteen, Rambutan, et.al at his home in Bal Harbour, FL granted it is a protected area with the ocean on one side and the inter-coastal waterway on the other. A recent study by NASA showed that wetlands stay warmer than developed areas and wetland restoration is already happening in South Florida.(1) Could this give us the buffer we need to grow these species? Botanists developed a spray that, when misted over a plant, will help it endure temperatures 2.2 to 9.4 degrees Fahrenheit colder than it would without the spray, depending upon the species. The spray, called Freeze-Pruf, reduces the freezing point of water inside the tissues of the plant by means of a mixture that combines five ingredients in a water-based spray formula. One spray works for four to six weeks, lowering the temperature at which damage first becomes noticeable as well as the temperature that would normally kill the plant.(2) During my research for this article I have discovered we only have really cold temperatures in four months November, December, January and February, with the worst temps in January and February. According to the records I researched, it has dropped below 32°f twenty-five times in the last one hundred years and out of those seventeen were before 1980.(3) So cold temperatures don’t happen very often. It is my opinion that more work needs to be done on selection of varieties that are more tolerant of cold. Experiments like these aren’t for an average grower. However, some of us, in the spirit of Bill Whitman & Julia Morton, have the patience to try our hand at it. As our climate changes we need to continue to have trials of each of these species. I’m already recording daily highs, lows and rainfall. Also, I’m keeping records of damage caused by the cold and I encourage you to do so as well. I challenge all you rare fruit fans to try your hand at growing rare fruit trees you thought weren’t possible, or something that is truly rare. I’ll share some of these species in my next article.

(1)http://www.nasa.gov/vision/earth/environment/wetland_freeze.html
(2)http://physicsnow.net/dbis/stories/2008/18130.html
(3)http://www.srh.noaa.gov/mfl/localdata.php

References;
Freeze Damage to Tropical Fruit Trees in 1940 S. J. Lynch
Freeze Damage to Tropical Fruit Trees in 1957-58 R. Bruce Ledin
Freeze Damage to Tropical Fruit Trees in 1977 C. W. Campbell, R. J. Knight, N. L. Zareski

Freeze Protection of Tropical Fruit Crops 2008 Dr. Jonathan H. Crane