Phytophthora sp a causal agent of leaf soft rot disease of nutmeg in Indonesia

Abstract

Leaf soft rot symptom has been found in nutmeg germplasm collection of Indonesian Spices and Medicinal Crop Research Institute (ISMCRI), Sukabumi, West Java. The research was aimed to identify a causal agent of leaf soft rot disease and the effectiveness assay of fungicides on colonies growth. Based on morphological observations, Phytophthora was found consistently from the infected leaf samples and the fungus characteristic was identic to Phytophthora palmivora. Host range test showed the ability of the fungus to infect pepper and rubber plants. The effect of temperature on fungal growth was tested by planting the fungus on Carrot Agar Medium (CAM), and incubated at 25°C, 28°C, 31°C and 34°C. The efficacy of propineb and mancozeb on inhibiting the growth of fungal colonies was tested by food poisoning technique. Koch’s postulate test showed that the first soft rot symptom on the inoculated leaves appeared on the second day and the infected leaves began to fall on the fourth day after inoculation. The optimum temperature for the fungus to grow is 28°C. The result of the efficacy test showed that mancozeb was more suppressing the growth of the Phytophthora than propineb