E.E. Trujillo, Department of Plant and Environmental Protection Sciences, UH-CTAHR
J.Y. Uchida, Department of Plant and Environmental Protection Sciences, UH-CTAHR
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Potential biocontrol agents to control banana poka vine from high elevation forests of Hawaii are being evaluated.
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Contact Dr. Eduardo Trujillo (trujillo@hawaii.edu) and Dr. Janice Uchida (juchida@hawaii.edu)
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OBJECTIVES
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- Monitor host-parasite and collect field biological information on Septoria passiflorae pathogen of banana poka and Septoria sp. on bush lantana in forests of Hawaii.
- Determine host range, and gather epidemiological data of Xanthomonas sp. and Colletotrichum gloeosporioides pathogens of banana poka.
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APPROACH
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Pathogens of banana poka and bush lantana will be released at selected sites in forests of Hawaii by hand spraying spore suspensions of 1 x 106 in a solution of 2% sucrose, 0.5% gelatin. Lesion numbers on infected leaves will be counted and disease curb determined. Sample monitoring will be done monthly and data will be analyzed statistically using one-way ANOVA and LSD comparisons of means. Efforts will be made to determine biomass reduction at 1 and 2 years after release of the biocontrol fungus.
Terraria will be used for inoculation and for host range studies with Xanthomonas sp. and Colletotrichum gloeosporioides on a number of native Hawaiian plants and other related plants to banana poka. The bioherbicide approach will be used to assess their biological control potential.
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PROGRESS October 1998 to September 1999
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Epidemics of Septoria leaf spot of banana poka in high elevation forest of Hawaii at 1,480-1560 m were caused by Septoria passiflorae axesual spores. The spores produced by the pycnidia on both surfaces of the infected leaves are distributed throughout the forest canopy by microscopic water droplets characteristic of foggy weather. These droplets, when driven in by wind through spore horns or cirri, collect spores as they pass making the pathogen airborne. This is a novel distribution mechanism for pycnidia leaf spotting fungi. Banana poka weed biomass reduction at Hilo Forest Reserve and Puuwaawaa Wildlife Sanctuary caused by this biocontrol agent surpasses 90-95% at 6 data point sites. Infected air-dried banana poka leaves, stored at -10C, can be used to distribute inoculum to banana poka areas with no disease.
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IMPACTS
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Control of banana poka vine from high elevation forests of Hawaii will encourage reforestation of native koa. The dollar value of this biocontrol agent at Hilo Forest Reserve, and Puuwaawaa Wildlife Sanctury is estimated at more than $50 million.
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