EFFECT OF CLIMATIC FACTORS ON PHYTOPHTHORA LEAF INFECTION IN BLACK PEPPER GROWN IN ARECANUT-BLACK PEPPER MIXED CROPPING SYSTEM

Abstract

Effect of climatic factors on the occurrence of foliar infection in black pepper caused by Phytophthora palmivora MF4 was studied during the years 1984-86 in arecanut black pepper mixed cropping system. The correlation studies between the disease recorded at weekly intervals and the meteorological factors prevailing during the preceding seven days showed a positive correlation between the rainfall, number of rainy days and relative humidity whereas temperature and sunshine hours had a negative correlation. Average climatic factors worked out during increasing and decreasing phases of the disease showed that factors such as low temperature (22.7-29.6"C). shorter duration of sunshine (2.8-3.5 h/day) high rainfall (15.8-23.0mm/day) and high relative humidity (81-99%) contributed to the increase n disease