Hawaii’s anthurium growers cope with plant disease

A destructive pathogen is impacting Hawaii’s production of anthuriums, a plant known for its heart-shaped flower and leaves, say plant pathologists with The American Phytopathological Society (APS).

Anthuriums’s flower portion, or spathe, is available in a variety of colors including brilliant shades of red, orange, pink, and salmon. Although they originated in Central America, anthuriums are now the most important cut flowers in the Hawaiian floriculture industry, said Anne Alvarez, Department of Plant and Environmental Protection Sciences, University of Hawaii, Honolulu, HI. In 2004, Hawaii’s cut flower sales were valued at $13.1 million, with anthuriums ranking as the top seller at $4.7 million. At the peak of production in the early 1980s, Hawaii was supplying up to 232,000 dozen flowers per month to the world.

Anthurium production levels have been significantly reduced due to bacterial blight caused by the bacterial pathogen Xanthomonas axonopodis pv. dieffenbachiae. This disease was first reported in Kauai, HI in 1971 but had little impact on the industry until 1981 when plants began to die in large numbers on farms in Hilo, HI. “Once introduced into a new growing area, bacterial blight may result in 50-100 percent loss of plants,” said Alvarez.

The disease reached epidemic proportions during 1985-1989, destroying the production of approximately 200 small farms existent in Hawaii at the time. During the 1980s, Hawaii’s anthurium production dropped from a record high of approximately 30 million stems to 15.6 million stems in 1990. Following implementation of an integrated disease management program, losses were eventually reduced to five percent or less, Alvarez said.

Various components of an integrated disease management program for anthurium blight include sanitation, disinfection of harvesting containers, chemical sprays, modification of cultural practices, production of pathogen-free planting stocks in vitro, use of resistant cultivars, and biological control.