Role of relative humidity and temperature on the survival of Phytophthora palmivora, the incitant of coconut bud rot
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Date
2004
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Abstract
A random survey on bud rot disease of coconut, caused by Phytophthora palmivora, carried out in Kasaragod, Kannur and Calicut districts of Kerala revealed that, there is correlation between the disease incidence and the location of the palms. The disease incidence was high in the hilly tracts (300-1350 MSL), when compared to that of the plains (150 -300 MSL). Studies on the survival off? palmivora propagules in nature revealed that the pathogen survives in the crown of healthy and diseased palms. However, the percentage of survival was high in the endemic areas (Mandapam, Josegiri and Kuttiadi), both in the case of diseased and healthy palms compared to that of areas with lesser disease incidence. Statistical analysis of moisture content I in the debris of crown at different places (CPCRI Kasaragod, Mandapam and Josegiri) during April, July, October and January revealed that differences due to places, season (months) and their interactions are highly significant. Epidemiological observations indicates that macro and micro-temperatures in Mandapam and Josegiri were low, while the micro and macro humidity recorded was high from October-January compared to that of Kasaragod. This shows that the temperature and humidity in the coconut gro\\?ing tracts of hilly areas of Kasaragod, Kannur and Calicut districts are suitable for the survival of the pathogen in the crown during almost all months, resulting in the high frequency of disease incidence during monsoon season and which is also responsible for the continued infection upto January. Examination of the rain water collected from bud-rot affected coconut gardens also indicated that the pathogen surviving in the crown debris can act as a source of inoculum which spreads to the neighboring palms through rain splashes. Based on the above data, it is possible to predict the bud rot incidence well in advance.
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Keywords
Coconut, bud rot, Phytophthora palmivora, epidemiology, forecasting model
Citation
Journal of Plantation Crops, 2004, 32 (2): 28-34