Minnesota, February 12, 2004 (ENS): The U.S.
ornamental plant industry, which includes deciduous
and evergreen trees, shrubs, cut flowers, and foliage
and flowering potted plants, grew in value to $14.3
billion in 2002. But an increase in the spread of rust
diseases could have devastating results on ornamental
crops industry, warn pathologists with The American
Phytopathological Society (APS).
According to Dr. James Buck, assistant plant pathology
professor at the University of Georgia, a fungal infection
called rust has the ability to negatively affect production
of many ornamental crops such as the crops of geranium,
chrysanthemum, gladiolus, and daylily produced in the
"Because live plants are shipped all over the
country, the risk for rapid disease spread is substantial,"
said Buck. While rust fungi do not usually kill infected
plants, infection by rusts will reduce plant health
and flower production.
Currently, more than 125 species of fungi that cause
rust have been reported on 56 different ornamental crops.
"Rust pathogens cannot be adequately detected
on contaminated but symptomless plant material entering
the U.S. or moving state-to-state," said Buck.
"As such, rust pathogens have the potential to
dramatically affect ornamental crop production."
Rust spores can lodge in the crown of plants that have
had foliage removed for shipping purposes, the APS cautions.
Symptomless plants are then moved long distances through
international or interstate trade, dispersing the pathogen
and introducing it into areas that were previously free
While quarantine restrictions and eradication efforts
are used to manage rust outbreaks and minimize potential
disease loss, such efforts are not perfect and can have
a significant economic impact on crop production.
International trade of ornamental crops has made the
exclusion of rust pathogens difficult because contaminated
plant parts may be symptomless and inadvertently allowed
to enter quarantined areas. With repeated introductions,
pathogens may become widespread and cause the quarantine
According to Buck, plant pathologists are currently
working on improved detection methods and developing
new diagnostic methods to quickly and accurately identify