viral diseases of tomato and papaya. major causative agents and insect vectors. major symptoms and its management practices. plant pathology and viral diseases. prepared by Bsc. Ag graduate Mr. Bhimsen Mahat.

1. Institute of Agriculture and Animal science (IAAS, TU)
Lamjung campus
Sundarbazar, lamjung
Assignment of
Crop Diseases and their management
[PLP 321]
Presented By:
Bharat Khadka (21) Bhimsen Mahat(22) Bhuwan Gauli(23) Bibek Ghimire(24)
Bibek Sharma Sapkota(25)

2.  Annual herbaceous belongs to solanaceae.
 Day neutral crop and can be grown in field as well
as poly house.
 Types: determinate and indeterminate.
 Most important high value crop.

3.  Among the various factors, viral diseases cause
significant yield loss.
 Tomato leaf curl virus( TLCV), Tomato mosaic
virus(ToMV), Tomato spotted wilt virus(TSWV),
cucumber mosaic virus

4.  Yield loss 40%
 First reported in 1995
Transmitted by
 white fly (Bemisia tabaci)
Symptoms:
 Edge of leaves curl upwards and become hairy in
touch.
 Older leaves become leathery and turn yellow then
brown and dry.

5.  Stunted and bushy,
small fruits and flowers drop.

6.  Loss up to 23%
 Transmitted by aphids
and leaf hoppers
Symptoms:
 Mottled light and dark green on leaves.
 Leaves may be curled, malformed or reduced in
size giving fern-leaf shape
 fruits are deformed with internal browning

8.  Transmitted by thrips
 Host: tomato, tobacco, peppers
Symptoms:
 Bronzing of the upper sides of young leaves
 Later develop distinct necrotic spots
 Leaves may cupped downward
 On ripe fruit chlorotic spots and blotches appear,
often concentric rings.

10. Management of viral diseases in tomato:
 Use virus free seedling
 Use of resistant variety
 Traps: Yellow sticky trap (whitefly), blue sticky
trap(thrips), yellow pan trap(aphids)
 Crop rotation with non host crop and mulching
 Destroy the infected parts and plants

11. Management of viral diseases in tomato:
 Use natural enemies: spiders, lady birds, hoverfly etc.
 Hot water treatment of seed at 500c for 25 min
 Soak seeds in a 10% solution of tri sodium phosphate
(Na3PO4) for at least 15 minutes before planting.
 Spray neem based insecticides like altineem @3-5ml/ltr
water.
 Foliar spray of rogor (0.05%) on first appearance of the
disease symptom.

12.  Tropical fruit belongs to caricaceae family
 Quick growing tropical fruits
 Red lady 718, Pusa delicious, pusa giant, pusa
dwarf etc are popular varieties
 Highly socioeconomic fruit as short duration, high
yield, continuous bearing
 Among the various factors, viral diseases cause
significant yield loss.

13.  Transmitted by aphid
Symptoms:
 The leaves are reduced in size
 Show blister like patches of dark-green
tissue, alternating with yellowish-green
lamina
 leaf petiole is reduced in length
 Vein clearing and downward cupping of
leaves

15. Managements:
 Use virus free seedling
 Crop rotation with non host crop
 Do not grow papaya with cucurbits but Beans and
sweet corn could be used as intercrops
 Destroy diseased parts and plant
 Control the population of aphids

16.  Application of carbofuran @ 1kg a.i/ha at seed
sowing followed by 2-3 foliar spray of
phosphamidon (0.05%)

17.  Transmitted by aphids mainly Myzus persicae
Symptoms:
 Mottled and distortion of leaves with and have rings
 Infected leaves modified into tendril to give shoestring
appearance
 Water soaked chlorotic spot on stem and petiole

20. Management:
 Disease free seedlings raised in modern insect
proof nethouses or polyhouses
 Rouging and destruction of diseased plants
 Control the population of aphids
 Application of carbofuran @ 1kg a.i/ha at seed
sowing followed by 2-3 foliar spray of
phosphamidon (0.05%)

21.  Raising barrier crops like Maize or Hibiscus
sabdarifa on the boundaries of the field
 Spray with di-methoate (0.05%) and azadirachtin
(0.06%) alternately at fortnightly interval that
reduces aphid population and PRSV incidence
 Spray white oil emulsion at 1% concentration in
water.

22.  Transmitted by white fly
Symptoms:
 Severe curling, crinkling and deformation of the
leaves
 In severe cases complete defoliation of the affected
plant
 stunted growth with reduce fruit yield

24. Management:
 Removal and destruction of the affected plants
 Checking the population of white flies
 application of Carbofuran (1 kg a.i./ha) at the time
of sowing and 4-5 foliar sprays of Dimethoate
(0.05%) or Metasystox (0.02%) or Nuvacron (0.05% )
at an interval of 10 days effectively controls the
whitefly population.