Which Ralstonia Is It?

November 5, 2004 - 12:29

After weeks of speculation and industry confusion, the Plant Protection and Quarantine (PPQ) division of the USDA has announced that the initially identified outbreak “of what was thought to be Ralstonia solanacearum race 3 biovar 2 in geranium samples taken from a greenhouse and pond in Quincy, Fla., in September 2004,” was in fact not. According to Nolan Lemon, spokesperson for APHIS, test results have confirmed that the disease on the plants in Florida is a version of Ralstonia but tests proved that it is not the Ralstonia solanacearum race 3 biovar 2 version. This means that, according to the USDA, Ralstonia solanacearum race 3 biovar 2 has not been in the United States since the outbreak in early 2004.

Other, less devastating strains of Ralstonia are typical in Florida and have been reported since 1984, according to the PPQ. APHIS scientists retested cultures isolated from the Quincy establishment in 2002 and identified them as R. solanacearum biovar 1, which is not on the bioterrorism list like its cousin Ralstonia solanacearum race 3 biovar 2 As of right now, according to Denise Feiber, public information director from the Florida Department of Agriculture and Consumer Services, Division of Plant Industry, the suspect Florida nursery is no longer on hold since the test results came back negative.

Since the suspect facility is in the heart of Florida tomato country, signs of wilt are somewhat frequent, and at first glance it is difficult to see the differences in race and biovar, hence the further testing. Additional testing to determine race is in progress according to Lemon.

“We are not categorizing the outbreak as a quarantine pest. APHIS scientists are collaborating with leading Ralstonia researchers to learn more about the bacteria,” explained Feiber. She also said “It was our understanding that some of those results were preliminary and that there are different levels of analytical tests that they do. During the initial testing the results showed race 3, but further into the testing is when the researchers determined that is wasn’t.”

At the beginning of October the USDA reported, also in the Phytosanitary Alert System, that, “PPQ has confirmed Ralstonia solanacearum race 3 biovar 2 in geranium samples taken from a greenhouse in Quincy, Fla., on Sept. 10, 2004. Subsequent tests of water samples taken from a retention pond also tested positive.” According to Lemon, the initial confirmation referred to plants behaving a lot like r3b2, but later testing confirmed that it was not r3b2.

Ever since the announcement of this outbreak at the Florida facility, industry officials have been extremely cautious of saying it was another actual outbreak because of all of the odd details that surrounded the news. The production facilities in Mexico continuing to test negative was one of the major red flags, as well as the fact that the Quincy facility is right in the heart of Florida’s tomato country. Tomatoes are a known carrier of Ralstonia. All throughout the ordeal, news came out that three labs confirmed that the outbreak was indeed Ralstonia solanacearum race 3 biovar 2, but now it is being reported by the Florida Department of Agriculture, Plant Division that those confirmations were only preliminary and with further testing, the race and biovar were found to be wrong from the initial findings. Overall, the good news for growers and breeders is that there is not another outbreak of Ralstonia solanacearum race 3 biovar 2.

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