The document discusses the economic impact and management of the Papaya Ringspot Virus (PRSV), which affects papaya crops in tropical and subtropical regions, including India. It highlights the virus's symptoms, such as mottled and distorted leaves, reduced fruit size, and circular water-soaked spots on fruit, as well as its transmission by aphids. Management strategies include using disease-free seedlings, transgenic papaya varieties, planting barrier crops, and applying specific insecticides to control aphids and reduce virus incidence.

1. PAPAYA RING SPOT
Dr. P. KISHORE VARMA
Assistant Professor,
PJTSAU, Hyderabad

2. Economic impact
• PRSV occurs in most tropical and
subtropical areas where Papaya is grown
• USA, the Carribbean countries, Africa,
India and Taiwan
• In India 1st
reported from Mumbai and
Pune and occurs more in central India
• The incidence of PRSV to the tune of 75-
100% was reported from Uttar Pradesh,
Maharashtra, Gujarat, Bihar and M.P.

3. Etiology
• Papaya ringspot virus (PRSV)
• PRSV is a potyvirus with long flexuous rod shaped
particles having ssRNA as genome
• Other hosts: Cucumis sativus, Cucurbita pepo, C. maxima,
Citrullus vulgaris, Luffa acutangula, Lagenaria siceraria,
Safflower and some ornamental plants
Long flexuous rod like particles
of PRSV-P strain

4. Myzus persicae
Etiology
Aphis gossypii
Aphids mainly Myzus persicae and other species like Aphis malvae and
A. gossypii transmit PRSV in a non-persistent manner

5. Favourable conditions
• Cool weather favours development of
severe leaf distortion symptoms
• Cultivation of susceptible hosts
• Prevalence of vector

6. Diagnostic symptoms
• Leaves are mottled and distorted with blisters
and have rings.
• In infected leaves, the lamina is reduced and
malformed and are often modified into tendril
like structures giving a shoestring appearance
• Water soaked chlorotic spots on tender stem
and petioles
• Under severe infection, older leaves fall down
and a small tuft of younger leaves are left at the
top in upright position

7. Mottling on foliage
Shoestring symptom
Foliar symptoms of Papaya ring spot

8. Shoestring symptom
Foliar symptoms of Papaya ring spot

9. Foliar symptoms of Papaya ring spot

10. Papaya orchard infected with PRSV

11. Diagnostic symptoms
• Plants are stunted and fruit set is reduced
• Fruits develop innumerable circular, water
soaked spots with concentric rings
• Sometimes fruit size is reduced with deformed
shape

12. Papya ring spot symptom on unripe fruit
Circular, water soaked concentric rings on fruit

13. Papaya ring spot on unripe fruit

14. Management
• Disease free seedlings raised in modern insect
proof nethouses or polyhouses
• Rouging and destruction of diseased plants
• Carica cauliflora is resistant
• Growing transgenic (coat protein mediated)
papaya varieties like Sun Up and Rainbow
• SunUp is a transgenic version of cultivar Sunset
and is homozygous for the CP gene. Rainbow is
an F1 hybrid created by crossing transgenic
SunUp with non- transgenic Kapoho.

15. Transgenic papaya varieties

16. Non-transgenic papaya Vs Transgenic papaya

17. Management
• Adjust the transplanting time to avoid the
aphid population
• Raising barrier crops like Maize or Hibiscus
sabdarifa on the boundaries of the field
• Spray white oil emulsion at 1% concentration
in water. Oil emulsion interferes with the
uptake and transmission of the virus by
aphid
• Spray with di-methoate (0.05%) and
azadirachtin (0.06%) alternately at fortnightly
interval that reduces aphid population and
PRSV incidence