On National Teacher Day, meet the 2024-25 Kenan Fellows
RICE TUNGRO VIRUS
1. COLLEGE OF AGRICULTURALTECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
RICE TUNGRO VIRUS
STUDENT: COURSE TEACHER:
ATCHAYA. M Dr. S. PARTHASARATHY
(2016021005 ) Assistant Professor (Plant Pathology).
2. SIGNIFICANCE
• Tungro means degenerated growth.
• Tungro is called as cancer because of severe damage.
• Tungro was first diagnosed in 1963.
• The disease is reported from Philippines, Malayasia,
Indonesia, Thailand, India and Pakistan.
3. • Rice tungro virus disease is one of the most
damaging and destructive of rice in south and south
east Asia and also in southeren parts of china
(Krishnaveni et al., 2011).
• Indonesia is perpetually affected by the disease, the
area affected varying from 16,000 to 25,000 ha
annually.
• The annual loss due to tungro is estimated at US $ 1.5
billion globally (Herdt, 1988).
4. DISTRIBUTION IN INDIA
• West Bengal
• Andhra Pradesh
• Madhya Pradesh
• Bihar
• Assam
• Tamil Nadu
• Karnataka
• Kerala
5. DISTRIBUTION IN ANDHRA PRADESH
• The distribution of rice tungro has become sporadic
in most of the rice growing tracts of Andhra Pradesh
especially in some of the districts like Medak and
Nalgonda .
• Till now the disease has been reported from East
Godavari, Chittoor and Prakasam districts of Andhra
Pradesh.
8. SYMPTOMS
• Symptoms depend upon host cultivar, in the cultivar
TN 1, seedlings show stunting with mottling and
yellowing of leaves.
• Reduced tillers, yellowing and orange yellow
colouration of leaves is a common symptoms.
• Delayed flowering
• Most panicles sterile or partially filled grains
9. Yellowing from tip to
downwards
Stunted with reduced
tillering
www.Knowledgebank.irri.org>item>tungro
13. PATHOGENS CHARACTERS
• RTBV –dsDNA bacilliform virus, which cause mild
stunting and yellowing of leaves.
• It belongs to Budna virus group, the particle 100-400
nm long and 30-35nm in diameter.
• RTSV – ssRNA virus, which causes only very mild
stunting, no without leaf symptoms.
• It is isometric with a diameter of 30-33 nm.
14. SYSTEMATIC CLASSIFICATION
• Group : Group vii
(dsDNA)
• Family: Caulimoviridae
• Genus : Tungro virus
• Species: Rice tungro
bacilliform virus (Salto
in 1975)
• Group : Group iv
(ssRNA)
• Family : Sequiviridae
• Genus : Waikavirus
• Species: Rice tungro
spherical virus
15. GREEN LEAF HOPPER VECTOR
• Tungro viruses are transmitted by six leafhoppers
species, which are in the genus of Nephotettix
species.
• Nephotettix virescens lays its eggs in batches of up to
44 in the tissues of leaf sheath of rice tillers .
• After hatching, there are five nymphal stages before
adult emergence. At the optimal temperature for
development (30 to 35ºC).
17. HOSTS
• Oryza species are the main host but at least 63 species
of grasses can be infected .
• Natural occurrence on grasses in and around rice
fields is reported.
• However, all except Oryza species are poor hosts of
the vectors.
• Horticultural crops - Black pepper, Toro, Cocoa and
Yam.
19. VIRUS-VECTOR INTERACTIONS
• When young (nymphs) and adult green leafhoppers
feed on diseased plants, virus particles get attached to
mouth parts(stylets). As these insects fly and feed on
other plants, the virus particles from the stylets get
introduced into healthy plants.
• The insects pick up virus particles within 7 minutes
of feeding and can transmit these particles to other
healthy plants. Generally, tungro virus disease
symptoms appear
20. • Transmission mainly by the leaf hopper vector
Nephotettix virescens Males, females and nymphs of
the insect can transmit the disease.
• Both the particles are transmitted semi-persistently, in
the vector the particles are noncirculative and
nonpropagative.
• Plants infected with RTSV alone may be
symptomless or exhibit only mild stunting.
21. • RTBV enhances the symptoms caused by RTSV.
• RTSV can be acquired from the infected plant
independently of RTBV, but acquisition of RTBV is
dependent on RTSV which acts as a helper virus.
• Both the viruses thrive in rice and several weed hosts
which serve as source of inoculum for the next.
22. EPIDEMOLOGY
• Mode of spread-Vector borne (Nephotettix virescens )
• Primary source for tungro, includes:
Stubbles of previous crops
Infested plants in nearby rice fields
23. FAVOURABLE CONDITIONS
• Presence of virus sources
• Presence of vector
• Age and susceptibility of host plants
• All growth stages of the rice plant specifically the
vegetative stage.
• Ecosystem: Irrigated and rainfed lowland
ecosystems.
24. DIAGNOSTIC METHODS
There are 5 different diagnostic techniques for tungro
1) Symptomatology
2) Transmission test
3) Iodine/starch test
4) Serological test
5) Electron microscopy
The application of one technique or a combination
of several techniques will greatly help in correct
identification.
25. MANAGEMENT OF RICE TUNGRO VIRUS
CULTURAL METHODS
• Planting of resistant varieties against tungro virus
disease is the most economical means of managing
the disease.
• Use Resistant varieties like IR 36, IR 50, ADT
37, Ponmani, Co 45, Co 48, Surekha, Vikramarya,
Bharani, and white ponni .
27. CULTURAL METHOD
• Neem seed cake applied at 5 kg/0.032 ha of nursery
followed by foliar spray of 5% neem kernal extract in
the main field reduces vector population and
incidence of tungro (Rajappan et al. , 2000).
• Plouging and harrowing the field to destroy stubbles
right after harvest in order to eradicate other tungro
hosts are also advisable.
• Destruction of weed hosts on bunds.
29. MECHANICAL METHOD
• Light traps are to be set
up to attract and control
the leaf hopper vectors
as well as to monitor the
population.
• This should be practiced
every day.
30. CHEMICAL METHODS
• Leaf yellowing can be minimized by spraying 2 %
urea mixed with Mancozeb (Indofil M-45) at 2.5
gm/lit.
• Instead of urea foliar fertilizer like multi-K
(potassium nitrate) can be sprayed at 1 per cent which
impart resistance also because of high potassium
content.
• Spray insecticides twice, 15 and 30 days after
transplanting .
32. BIOLOGICAL METHODS
• Two fungi, Beauveria bassiana and Paecilomyces
amoeneroseus are reported as parasites of rice green
leaf hopper, Nephotettix virescens.
• Spray of conidial suspension of the fungi on rice
plants kills the vectors (Niazi et al., 2002).
33. REFERENCES
Rangaswami, G and Mahadevan., A. 1999. Diseases
of Crop Plants in India. PHI learning private limited,
New Delhi.
Singh. R.S., 2009. Plant Diseases. Oxford and IBH
Publishing CO. PVT.LTD, New Delhi 110 049.
