One of the scariest potentially invasive pests is also one of the smallest. Known as `ohi`a rust, Puccinia psidii<\/i> is a relative latecomer, being discovered on `ohi`a seedings in an O`ahu nursery in 2005. Since then, it has spread throughout the state. While `ohi`a have escaped its worst effects, the strain of the rust that is present in Hawai`i has devastated rose apple (Syzygium jambos<\/i>) and has been found to kill individuals of two native species, Eugenia reinwardtiana and the endangered Eugenia koolauensis, both known as nioi in Hawaiian. All affected plants are in the Myrtaceae family.<\/p>\n
\tLast year, in response to the alarm raised by natural resource managers, the state Department of Agriculture adopted an emergency rule, banning the import of Myrtaceae plants and plant parts from the states of California and Florida, and from Central and South America. When the rule expired in late August, the DOA was still working on a permanent rule.<\/p>\n
Anne Marie LaRosa of the U.S. Forest Service\u2019s Institute for Pacific Island Studies, in Hilo, gave an overview at July\u2019s Hawai`i Conservation Conference of what, she said, is not only \u201cpossibly the greatest threat to `ohi`a,\u201d but also \u201ca serious threat to global biodiversity \u2026 equivalent to other introduced epidemic tree diseases, such as Dutch elm blight.\u201d Unlike the wiliwili gall wasp, the puccinia rust has been known to science for more than a century, having been described on guava in Brazil in the 1880s. No one was alarmed over its presence there until the 1930s and 1940s, LaRosa said, when Brazil\u2019s fledgling eucalyptus industry was affected by the rust. Since then, it has spread to Florida and the Caribbean, where it ravaged allspice trees, to California. \u201cThe concern now is that Hawai`i is the gateway for Australia, New Zealand, and Samoa.\u201d<\/p>\n
\t\u201c`Ohi`a is at stake here, the very fabric of our forest,\u201d LaRosa said. \u201cIf we have an epidemic like Dutch elm disease or chestnut blight, we\u2019re looking at changes in our ecosystem\u2026 Over 400,000 acres are potentially impacted.\u201d<\/p>\n
\tThe good news is that the strain of rust identified in Hawai`i, while it can be found on `ohi`a, has limited impact. \u201cWe see it everywhere, but it\u2019s not that bad on `ohi`a,\u201d she said. Other species affected elsewhere, such as eucalyptus and allspice, have also avoided being hard hit in Hawai`i.<\/p>\n
\tBut that could change quickly if a new strain arrives in the islands. At the moment, LaRosa said, \u201cwe\u2019re working with a single strain, called the rose apple strain. There\u2019s little genetic variability now, indicating the rust is something that recently arrived and has not yet undergone change.\u201d<\/p>\n
\tHawai`i Department of Agriculture adopted an interim rule prohibiting the importation of all Myrtaceae plants and plant parts. Even asymptomatic plants could still harbor the rust, LaRosa said: \u201cYou can\u2019t inspect for rust.\u201d<\/p>\n
\tBut is the ban on imports of Myrtaceae plants and plant parts enough?<\/p>\n
\tLaRosa herself identified a large gap in the process. \u201cThe flower trade is very active,\u201d she said. \u201cWe believe that\u2019s how the rust came in.\u201d In 2007 and 2008, cut flower material, in pre-arranged bouquets, was intercepted coming into Maui. \u201cPeople grow flowers, send them to a central location to be bundled into bouquets, where it\u2019s mixed with Myrtaceae\u201d and other flowers from other plants known to be hosts to the rust.<\/p>\n
\tIn another presentation, David Simmons, a student in the University of Hawai`i Department of Plant and Environmental Sciences, reported that the rust had been found on two popular landscape plants, the brush cherry (Eugenia paniculatum<\/i>) and the downy rosemyrtle (Rhodomyrtus tomentosa<\/i>), which is also naturalized and considered a serious pest in forests on Kaua`i, O`ahu, and Hawai`i. (On Maui, several rosemyrtle infestations were found and eliminated, but monitoring continues.)<\/p>\n
\tSimmons reported that the larvae of the diptera fly Mycodiplosis pucciniae<\/i> had been found eating spores of the rust on all the islands. \u201cIt eats a lot of spores,\u201d he said, and \u201chelps greatly to reduce the amount of inoculum in nature.\u201d When asked where the fly was from, Simmons said that no one knows if it\u2019s native or not.<\/p>\n
\tThe fly doesn\u2019t seem to be helping the native nioi ward off the ravages of the rust, however. Chris Kadooka, also with the UH Department of Plant and Environmental Sciences, reported on his work developing a genetic profile of the Hawai`i rust strain and what he had seen when collecting rust samples in the wild. \u201cWhat we\u2019ve seen in the field is moderately affected `ohi`a\u2026 Where I\u2019ve seen it bad is where we have a roseapple source that\u2019s nearby.\u201d As for the nioi: \u201cWe found one fungicide that might be protecting it in the nursery, but we\u2019re pretty sure there\u2019s no fungicide approved for the forest. We went to Kahuku, and it\u2019s pretty sad. Lots of trees are susceptible.\u201d<\/p>\n
\tAccording to a source at the U.S. Fish and Wildlife Service, both species of native Eugenia<\/i> are \u201cequally affected, fairly severely. There\u2019s not much we can do.\u201d \u201cExtinction in the wild is a real possibility,\u201d said another botanist who wished not to be identified in print.<\/p>\n
\tLaRosa summed up the prospects for control: \u201cThere\u2019s no practical management for this disease in the wild. Prevention is the key.\u201d<\/p>\n
A Delayed Rule<\/b><\/i><\/p>\n
With the expiration of the emergency rule, the state has no ban on plants that might host the `ohi`a rust. Leslie Iseke, with the Plant Pest Quarantine branch of the state Department of Agriculture, said the department was intending to go forward with a permanent rule, but, \u201cunfortunately, it\u2019s taking longer than I thought to gather information.\u201d<\/p>\n
\tIn the meantime, she said in a phone interview, \u201cwe\u2019re setting up a plant quarantine policy on how we handle Myrtaceae coming into the state.\u201d<\/p>\n
\t\u201cWe\u2019re still targeting areas where the rust is known to occur \u2013 Florida, Central and South America,\u201d she said, but added that instead of the entire state of California subject to the Myrtaceae ban, based on information provided by California agriculture officials, the ban will probably be narrowed to just San Diego County,<\/p>\n
\t\u201cSo as we go along,\u201d Iseke continued, \u201cas we do the permanent ruling, the infested areas will be better defined, down to counties instead of states. And the same with South and Central America. If people know what areas are infested, we can define it that way \u2013 or it could be the entire continent, if the rust is more widespread.\u201d<\/p>\n
\tIn addition to learning more about areas of infestation, Iseke said that the DOA is also \u201cwaiting to see if we can get information regarding the types of strains that are out there\u201d so that the rule does not exclude the strain of rust already here. \u201cThat\u2019s how quarantine works,\u201d Iseke said. \u201cYou\u2019re trying to keep something out of Hawai`i, so it has to be something not already here.\u201d<\/p>\n
\tWhen asked whether identifying the rust down to the strain is a reasonable standard for a quarantine rule, Iseke agreed that tests to identify the strain of Puccinia<\/i> might take weeks or longer. Still, she said, \u201cto ban all Myrtaceae is probably not the way we want to go.\u201d With quarantine rules, she added, \u201cyou don\u2019t ban everything.\u201d<\/p>\n
\tThe emergency rule was broader than the final rule is likely to be, she said. \u201cWhen we did the emergency rule, not everyone was in agreement. It was like shutting the gate after the horse has escaped.\u201d<\/p>\n
— Patricia Tummons<\/p>\n
Volume 19, Number 3 September 2008<\/p>\n","protected":false},"excerpt":{"rendered":"
One of the scariest potentially invasive pests is also one of the smallest. Known as `ohi`a rust, Puccinia psidii is a relative latecomer, being discovered on `ohi`a seedings in an O`ahu nursery in 2005. Since then, it has spread throughout … Continued<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[157],"tags":[],"class_list":["post-1313","post","type-post","status-publish","format-standard","hentry","category-september-2008"],"_links":{"self":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/1313","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1313"}],"version-history":[{"count":0,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/1313\/revisions"}],"wp:attachment":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1313"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1313"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1313"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}