Before the Yellow Blight, and Now. --Paul Hampton Crockett __________ To my delight, a few months ago someone posted pics from the late 50s of both a view of my family home in the Roads, on 27th Road, and the nearby intersection of 27th and 7th Avenue. I recently got around to sending it out vie e-mail to my Dad and siblings. I received an email in response from brother Whit, asking if it was the yellow blight that had so changed the appearance and feel of the street. It had occurred to me that the view of the street seemed “different,” but I hadn’t really stopped to think about it. I realized that he was absolutely right. Known as Lethal Yellowing in the scientific community, the disease seemed to catch us completely off guard. And for several years thereafter, much about the phenomenon remained completely mysterious—including its cause—even to leading scientific specialists in the field. It had raged wildly throughout the Caribbean, especially Jamaica, and then hit Florida in 1971, when an early report noted a death toll of some fifty “Jamaica talls,” the majestic and lofty trees that lent South Florida much of its tropical “feel.” Even as it raged fiercely in Miami, the disease continued its northward march into Broward County, and beyond. In the first couple of years alone, the pestilence killed more than 300,000 beautiful palms. It acted fairly quickly, usually killing a tree completely within three months of first infection. The fronds would turn yellow, all new growth stop, and the whole top of the tree finally weaken and simply rot before crashing down to the ground. Only a stark and tell-tale “telephone pole” of its lower trunk would remain, grimly marking yet another spot where shade and beauty had once been. Within ten years the disease had killed an estimated 1.5 million palms in South Florida, or about 80 percent of the area susceptible palms. The cause was initially believed to be viral, because scientists had ruled out any other known causes, and a host of remedies attempted in growing desperation without success. The outlook was glum, as previous tree blights in the United States had proven both unstoppable and utterly devastating, notably the American Chestnut and Elm. By the late 1970’s two important and related discoveries finally provided the missing pieces of the puzzle, and thus direction for treatment. It turned out that the trees were being killed by the smallest possible living thing, a single-cell bacterium of the “mycoplasma” family: so tiny that it was difficult to isolate, and had long been assumed to be a virus. Once found, plentiful challenges abounded: the tiny monster lacked even a cell wall that was the “entry point” rendering entire classes of antibiotics effective against bacteria. The second breakthrough was the discovery that the deadly mycoplasma was being spread by small green insects about a quarter inch long, commonly known as “plant hoppers.” They’d move methodically and efficiently from tree to tree and then frond to frond, spreading the disease between trees much in the same way that hungry mosquitoes spread malaria between people. The most effective treatment turned out to be “vaccination” with the antibiotic tetracycline, first chosen because of its effectiveness in treating mycoplasmic infections. By 1982 the City of Palm Beach was able to save many of its tall coconut palms, the antibiotic reducing the rate of loss from 90% or higher to .05%. Hug a tree, when you think about it. They are giving you their best, every day. Thank you.
Posted on: Sun, 21 Dec 2014 04:28:57 +0000
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