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Anderson, R. C., and D. E. Gardner. 2001. Koa dieback in Hawaii. Abstracts, Joint Meeting of APS, MSA, and SON, August 25 - 29, 2001, Salt Lake City, Utah. Phytopathology 91(6): S3.
ABSTRACT
Koa (Acacia koa) dieback was first reported in natural stands on the island of Hawaii, and now occurs in koa plantations. Declining koa stands were sampled to assess the role of Fusarium oxysporum f. sp. koae in the current dieback, and to characterize the stand structure, soil properties, growth, and physiology of dieback-affected trees. Koch's postulates were demonstrated in greenhouse inoculations, but the pathogenicity of this fungus in the field may be influenced by predisposing factors such as host genotype and environmental fluctuations. Investigation of the stand structure revealed that trees >3cm dbh were equally affected by the dieback, and significantly more in smaller trees. Soil from dieback stands had higher % saturation and a lower pH that that from neighboring unaffected stands. Significant reductions in phyllode area, mass, and mass to area were detected on dieback affected trees. Phyllodes on dieback trees also had reduced stomal conductance and a higher (less negative) leaf water potential. F. oxysporum f. sp. koae appears to play an important role in regulating koa stand dynamics, growth, and physiology under environmental and edaphic conditions favorable for disease development.

FULL TEXT
Full text not available for this publication.

HOSTS
Acacia koa - Koa

PATHOGENS
No pathogen information available for this publication.


RELEVANT TO BIOCONTROL
No.

KEY WORDS
Acacia koa.

IMAGES
16_096 -- young dead Koa tree, HAVO 16_096 - young dead Koa tree, HAVO
PATHOGEN: Aspergillus melleus
24_090 -- wall poster, St. John 4th floor 24_090 - wall poster, St. John 4th floor
PATHOGEN: Aspergillus melleus
28_065 -- Fusarium growing from logs from dying koa tree on Mt. Tantalus, Oahu 28_065 - Fusarium growing from logs from dying koa tree on Mt. Tantalus, Oahu
PATHOGEN: Aspergillus melleus

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