Seedlings thus raised were used for screening. All the seedlings were artificially inoculated with papaya ring spot virus through artificial sap inoculation method. One gram of infected leaves was ground in a pre-chilled mortar and pestle using 1 ml of 0.1 M chilled sodium phosphate buffer (pH 7.2) containing -mercaptoethanol and 0.01 M EDTA. The sap was rub inoculated using the pestle or glass rod on the young leaves of seedlings at three leaves stage previously dusted with carborundum powder 600 meshes. After 5 min, the excess sap was washed off by distilled water.
The disease incidence and intensity scores were given using the scale adopted by Dhanam (2006). The scale consists of five levels
based on the symptoms exhibited by the infected plants as shown below.