TAMPA — The two patients were visibly sick — limbs sagging toward the ground and their color a deathly gray.Last week, a course of antibiotics was administered by syringe. It did little good.Death rites for the two $10,000 mature medjool date palm trees came in the form of a chainsaw on Monday. All that remained by afternoon were two mounds of sawdust.The trees, planted at Water Works Park less than two years ago, were the latest casualties of Texas Phoenix Palm Decline or TPPD, a bacterium that has spread through the Tampa Bay region attacking the signature item of Florida landscaping, the palm tree. Hillsborough and Manatee counties are considered ground zero for the disease in Florida. It was first discovered in Ruskin in 2008 and has since spread across the region to surrounding counties, including Pasco, Pinellas and Polk. Thousands of trees have now been infected, according to the botanists fighting the disease.With palm trees a staple of subdivisions and road medians, the disease also is hitting cities and developers in the pocket. Tampa Parks and Recreation Department no longer plants varieties of palm trees like medjool date palms and Canary Island date palms known to be susceptible to TPPD. And they are asking the city for an extra $50,000 to try to save existing trees with regular injections of antibiotics.Some experts at the University of Florida's Institute of Food and Agricultural Sciences are now advising landscapers to switch to varieties of palms that are immune to the disease, which is usually fatal to infected palms. Next month, the university's Fort Lauderdale Research and Education Center is hiring a specialist entomologist whose first job will be to figure out what plant-hopping insect is spreading the infection."It's active in that entire Tampa Bay area," said Monica Elliott, professor of plant pathology at the Fort Lauderdale center. "It certainly is spreading. I've even seen it on the Gainesville campus."Figuring out exactly how many trees have fallen to TPPD is difficult. Many dead trees end up as mulch or sawdust with no sample sent to labs or research centers to verify the cause of death, Elliot said. The disease typically blights Phoenix species of palms trees, which includes edible date palms, Canary Island date palms and sylvester palms. Alarmingly for the state, TPPD has also caused the death of cabbage palms, a native species of Florida, Elliot said.In addition to the Tampa Bay region, the disease has struck trees in Highlands, Lake, Sarasota, Charlotte, Duval, Lee, Palm Beach, Orange and Indian River counties, according to an IFAS report. The first sign of infection is the browning of lower branches as they die. As the disease spreads, it attacks and kills the spear leaf, the tree's newest leaf. Death soon follows. On Monday, workers from Plantz, a local horticulturalist firm, injected trees outside the Tampa Convention Center with antibiotics.First, a hole is drilled in the trunk and a valve inserted. Then a syringe is used to administer the antibiotic solution. The valve can be used for repeat injections. The treatment, which costs up to $30 each time and is applied three or four times a year, is not a guarantee against infection but has been shown to lower the risk of infection, said Steve Stanford, president and owner of Plantz."When it's already infected, it doesn't have a good rate of curing the tree, but there have been instances when it happens," he said.As a commercial horticultural agent with the Hillsborough County IFAS, Susan Haddock works with landscapers who have contracts to landscape new subdivisions and strip malls. She said the disease seems to be spreading along the Interstate 4 corridor and she has been advising landscapers to opt for less common varieties of trees, such as ribbon fan palms and mule palms, which are resistant to TPPD.But developers often want the prettiest species, she said, and those that are willing to try less popular trees often cannot find a supplier. "There aren't alternatives that have that majestic look," Haddock said. "In many cases, their clients are willing to take that risk and say I still want that palm."Tampa Parks and Recreation decided about a year ago it would no longer plant species of palms susceptible to TPPD, said Brad Suder, the department's superintendent of planning design. The city already spends $7,500 to inoculate 100 trees about 3 times per year. With the extra $50,000 in funding it has requested for the 2017 financial year, that number would rise to about 500. It includes trees in parks and medians. "It's pretty lethal in this region," Suder said. "The Tampa Bay region is getting hit very hard by it."Follow @codonnell_Times.