Effect of immune elicitors on the incubation period and disease incidence of PRSV infected plants of papaya (Carica papaya L.) cv. red lady at the seedling stage

The papaya ringspot virus (PRSV) is a deadly virus that causes ringspot disease of papaya in papaya growing regions of Andhra Pradesh. In this experiment, eight chemicals (Chitosan @ 200 ppm, Hydroquinone @ 200 ppm, Humic acid @ 20 ppm, Salicylic acid @ 150 ppm, Iso-nicotinic acid @ 150 ppm, 2- thiouracil @ 2500 ppm, Benzyl adenine @ 20 ppm, Cinnamic acid @ 150 ppm) with the potential to induce systemic acquired resistance (SAR) against PRSV were used. Chemicals were applied through four spraying methods: 5 days before, 5 days after, 5 & 10 days before, and 5 & 10 days after inoculation. Pre- inoculation application has shown superior results than post-inoculation. Single and double spraying of chemicals are statistically on par with each other. None of the chemicals evaluated exhibited total resistance to PRSV; however, they did extend the incubation period, resulting in a delay in symptom expression; Cinnamic acid and Benzyl adenine effectively delayed the incubation period and recorded the lowest disease incidence compared to other treatments as well as untreated plants. The results showed no significant difference between single and double sprays due to no significant interaction effects.