|Lee, Ing Ming|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/1997
Publication Date: N/A
Technical Abstract: Association of phytoplasma with quick decline of macadamia trees in Hawaii was reevaluated. Twenty samples were collected from affected and symptomless trees of the two susceptible cultivars cv. 333, and cv. 344 grown at Keaau and Kaiwiki, Hawaii. Ultrasensitive nested-PCR assays using two phytoplasma-universival primer pairs failed to detect phytoplasmas in any of the samples tested, contradicting recent reports (Borth et al. 1994 Phytopathology 84:1127; Borth et al. 1994. p. 72-73 in : Proc. HMNA 34th Annu. Conf.) That phytoplasma may play a role in macadamia quick decline. Phytoplasma association, if any, may be coincidental. In contrast, infection of trunks by two fungal pathogens, Nectria rugulosa and Xylaria arbuscula consistently associated with declining, but not healthy macadamia trees, supporting the previous suggestion (Ko and Kumimoto 1991. Plant Protec. Bull. 33: 204-209 and Plant Path. 40: 643-644) that girdling of trunks by fungal pathogens is a primary factor triggering sudden death of affected macadamia trees.