On March 10, 2008, the Florida Department of Agriculture and Consumer Services identified a suspected infection of gladiolus rust (Uromyces transversalis) on the leaves of gladiolus plants at a cut flower production farm in Hendry County, Florida. The diagnosis has been confirmed by the United States Department of Agriculture, Animal Plant Health Inspection Service, Plant Protection and Quarantine (USDA, APHIS, PPQ), making this the third year in a row that gladiolus rust has been found at this location. An Emergency Action Notification by USDA, APHIS, PPQ has been in place since the initial discovery in 2006, meaning that export of potentially infected material is prohibited unless the plants have been inspected and found free of visible symptoms.
In April of 2008, gladiolus rust was detected for the first time in Minnesota (map), the most northerly location of this pathogen in the USA to date.
Gladiolus rust primarily attacks hybrid cultivars of gladiolus grown for cut flower production, and if uncontrolled, can lead to total yield losses. This disease could have a significant impact if it becomes established or is transported into greenhouses or nurseries that grow gladiolus or related species. It is a plant disease of quarantine importance in the United States and Europe.
Background: Gladiolus rust (Uromyces transversalis) is a fungal pathogen native to South Africa. It has been reported from areas of southern Europe, Morocco, South America, Martinique, Australia, and New Zealand. It has been found in two Florida counties and was discovered in 2006 at commercial and residential sites in San Diego County, California. It has also been intercepted on cut gladiolus flowers entering the US from Mexico.
Hosts and Symptoms: The principal hosts of gladiolus rust are hybrid cultivars of gladiolus grown for flower production, but other tropical members of the Iridaceae, including Crocosmia, Tritonia and Watsonia species, are also susceptible. Infected plants develop small yellowish-orange pustules in rows across the width of the leaves, perpendicular to the leaf veins. Spores can be spread on the corms, rhizomes, and flowers of host plants, on infected leaves and stems, and can also be dispersed by wind.
Resources for additional information:
This pest alert is from the Massachusetts Introduced Pests Outreach Project, a collaboration between the Massachusetts Department of Agricultural Resources and the UMass Extension Agriculture and Landscape Program, aimed at preventing the establishment of new pathogens and pests in Massachusetts. To get alerts by email, visit http://massnrc.org/pests/signup.aspx.