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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Research Project #432027

Research Project: Statewide Survey and Characterization of Ceratocystis Species

Location: Tropical Plant Genetic Resources and Disease Research

Project Number: 2040-21000-017-09-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Mar 10, 2017
End Date: Jan 9, 2019

Objective:
The Rapid Ohia Death pathogen has so far only been found on the island of Hawaii, and restrictions have been placed prohibiting the movement of ohia plants and product off of the island. Concerns of the possible movement of the pathogen to the other islands are prompting expanded investigations into the causal agent, Ceratocystis. Previous studies of Ceratocystis in Hawaii identified Syngonium as a host. These plants are commonly grown as ornamentals in Hawaii, and the possibility that the strain that affects this host may be the same as or equally pathogenic to ohia, is of serious concern. A statewide survey of Syngonium, isolation of Ceratocystis from diseased plants, characterization of the Syngonium strains, and pathogenicity and host range testing of isolates on Syngonium and ohia are necessary to vet potential pathogens.

Approach:
Conduct an island wide survey for Ceratocystis on Syngonium on the island of Oahu. We will survey commercial nurseries, retail home and garden centers, private residences, research stations, botanical gardens, as well as community gardens for the presence of the disease. If disease symptoms are seen, samples will be collected and tested for the presence of the fungus. Disease samples will be plated on water agar and single hyphal tips of fungus that emerge will be transferred to vegetable juice agar for spore formation. Identification of fungi that emerge will be done by morphological characteristics of spores. A GPS reading will be taken for each site to aid in the development of an accurate distribution map. Cultures of Ceratocystis that are found, will be purified and stored in test tubes for pathogenicity and host range testing and sent to ARS in Hilo for genetic characterization. Standard operating procedures are in place in the laboratory at UH-Manoa for handling organisms isolated from samples not collected locally. Plant tissue samples, and materials coming in contact with those samples, will be sterilized with bleach or by autoclaving to prevent the introduction of organisms into the environment. A survey of other islands will be conducted. Commercial nurseries, retail home and garden centers, private residences, research stations, botanical gardens, as well as community gardens on the islands of Kauai and Maui, will be included. County agents on these islands will assist, by collecting disease samples and sending them to UH-Manoa for analysis. Pathogenicity and host range tests of Ceratocystis isolates on Syngonium and ohia will be conducted using well established standard operating protocols. When possible, samples of other diseased aroids will be collected and checked for the presence of Ceratocystis.