Spread of papaya ring spot disease

Papaya ring spot virus rapidly spreads in orchards once there is incidence through aphid vectors. The disease spreads mostly to adjoining healthy plants showing a typical circular pattern of disease spread. The rate of spread was slow in the beginning when very few infected plants were available but was very fast later when more number of infected plants were available in the orchard. It was observed that initially there was high (0.045) rate of infection in the month of November – December, which gradually declined to 0.004 in the first fortnight of March. The AUDPC gradually increased from 14.40 to 1478.32 corresponding to rise in per cent disease incidence. The rate of rise in AUDPC was high in monsoon when temperature was low.