2. Materials and methods
2.1. Plant materials, pathogen and plant extract
Banana cv. Rasthali and the F. oxysporum f. sp. cubense (Foc) isolate
(Race 1 – obtained from NRCB, National Research Centre for Banana,
Trichy, Tamil Nadu) were used in this study. Twenty-two plant
species with proven antifungal activity were selected for further
experiments (Table 1). Twenty-five gram of fresh leaves and rhizome
of turmeric were collected manually and extracted with
25 ml of sterile water (1 g/ml, w/v) using pestle and mortar. The extract
was filtered through muslin cloth and finally through Whatman
No. 1 filter paper and filter sterilized using Seitz filter
(45 lm). This formed the standard plant extract solution (100%)
(Shekhawat and Prasada, 1971). Ten milliliter of the standard plant
extract solution (100%) was mixed with 90 ml of the sterilized Potato
Dextrose Agar (PDA) medium to get the required concentration
(10%) of the plant extract. Twenty ml of this mixture was poured into
sterilized Petri dishes and allowed to set. A nine mm actively growing
PDA culture disc of Foc was placed at the center of the medium.
The plates were incubated at room temperature (28 ± 2 C) for seven
days. PDA without plant extract served as control. Three replications
were maintained for each treatment (Schmitz, 1930). The mean
diameter of the mycelial growth of the pathogen was recorded
and the results were expressed as per cent reduction of mycelium
growth over that of the control (Vincent, 1927).