Candidatus Phytoplasma palmae

Because of a protracted incubation phase in palms (Dabek, 1975), visual examination for LY symptoms is insufficient to conclusively determine the disease status of palms. To date, no biological or serological tests for detection of the LY phytoplasma have been successfully developed. PCR is the most sensitive test currently available for phytoplasma detection although this diagnostic method is complicated by the unusually low pathogen titres in palm tissues. When symptomless, pre-bearing coconut palms were evaluated for natural infection by LY, monthly assessment of spear leaf samples by LY-specific PCR in a year-long study revealed phytoplasma titres reached detectable levels in these palms between 47 and 57 days prior to the appearance of visible foliar symptoms (Harrison et al., 1994c).