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International Journal of Applied And Pure Science and
Agriculture
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e- ISSN: 2394-5532
p- ISSN: 2394-823X
STUDIES ON THE SYMPTOMS OF THE NECROTIC WILT OF SUNFLOWER
CAUSED BY TOBACCO STREAK VIRUS
Deepa Rani C. V1*, Dr. Susha S. Thara
2, Dr. Heera, G
3 and Narmadhavathy S.
4
Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, 695 522
ABSTRACT The sunflower necrosis disease of sunflower is one of the important diseases causing heavy losses
in edible oil seed in the country. It is an emerging threat for sunflower production system in
southern India, reported for the first time at Bagepally region of Kolar district and around
Bangalore in Karnataka during 1997. Later, its occurrence was reported from almost all
sunflower growing states of India, posing threat to sunflower cultivation. A new virus, imparting
necrosis leading to mortality of the plants have been reported. Considering the importance of
yellowing and necrosis disease in sunflower, the present study has much relevance and hence
will be a stepping stone to etiological aspects of virology. The virus isolates causing necrosis and
yellowing respectively have been identified as two different strains of Tobacco Streak Virus
(TSV) viz. Isolate-N (I-N) and Isolate-Y (I-Y). The two isolates caused different symptoms at
different growth stages of sunflower plants in Kharif and Rabi seasons.
Keywords: Sunflower, Ilar group virus, necrosis, yellowing, virus isolates, TSV,
Isolate-N, Isolate-Y.
I. INTRODUCTION Sunflower (Helianthus annuus L.) locally known as Suryaful / Suryakanti is a robust major
edible oilseed crop and has occupied a large area under cultivation in Karnataka. Sunflower is a
newly introduced crop in India. Maharashtra ranks second in sunflower production especially
Marathwada and Khandesh regions. The crop has significantly contributed to “Yellow Revolution”
in making India self sufficient in edible oil production. Andhra Pradesh, Karnataka, Maharashtra
and Tamil Nadu are the main sunflower growing states of India. The crop has been found to be
infected by many viruses viz. Tospo virus (Subbiah et al., 2000; Jain et al., 2000; Jagdale, 2000)
Cucumo virus (Venugopal et al., 1987, Salaman and Salanki, 2002) Poty virus(Chod et al., 1990;
Dujovny et al., 1998) and Ilar group virus (Ramiah et al., 2001; Ravi et al., 2001 ). Recently a new
virus imparting necrosis leading to mortality of the plants have been reported. The disease caused
an yield loss to an extend of 30-90 % (Halekari et al., 2005). The incidence is more in Kharif season
(80 %) while in Rabi season it is less (30 %). Tobacco Streak Virus has been reported to impart
necrosis in sunflower (Ravi et al., 2001; Ramiah et al., 2001; and Bhat et al., 2002). On the basis of
various studies conducted on the sunflower necrosis disease, the virus isolates causing necrosis and
yellowing respectively have been identified as two different strains of Tobacco Streak Virus (TSV)
viz. Isolate-N (I-N) and Isolate-Y (I-Y), a member of Ilar group of virus. Survey revealed that the
two isolates cause different symptoms in Kharif and Rabi seasons. Keeping the above points in
view, the present investigation was carried out to study the different symptoms caused by two
different strains of TSV.
II. MATERIALS AND METHODS
1. PREPARATION OF FIELD
Non-replicated field experiments on plots measuring 10 x 10 sq. using susceptible variety
Cargil were conducted in Kharif & Rabi season. Sowing was done with spacing of 60 x 15 cm. All
recommended cultural practices were followed. Field was exposed to natural infection of disease.
International Journal of Applied and Pure Science and Agriculture (IJAPSA)
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2. FIELD OBSERVATION AND INOCULUM SOURCES
Plants showing symptoms of necrosis and yellowing provided the primary source of
inoculums. Infected sunflower leaves were used to isolate the virus using 0.05 M potassium
phosphate buffer, pH 7.0 containing 0.02 M 2-Mercaptoethanol. Five hosts viz. Nicotiana
glutinosa, Nicotiana rustica and Nicotiana tabacum cv. White Burley and Chenapodium
amaranticolor were inoculated separately for isolating the virus.
Virus isolates obtained from sunflower plants with necrotic and yellowing symptoms were
designated as Isolate-N (I-N) and Isolate-Y (I-Y) respectively. Isolate-N was maintained on
Nicotiana glutinosa while Isolate-Y on Nicotiana tabacum cv. White Burley and Chenapodium
amaranticolor.
3. MECHANICAL TRANSMISSION
For mechanical transmission of I-N and I-Y , inoculum were prepared by grinding young
infected leaves of maintenance hosts showing symptoms in a chilled 0.05 M potassium phosphate
buffer with pH 7.0 containing 0.02 M 2-Mercaptoethanol with a chilled mortar and pestle. Test
plants were inoculated by conventional leaf rub method using a cotton swab. Carborundum powder
(800 mesh) was used as an abrasive. Immediately after inoculation, leaves of the test plants were
washed with water. Test plants used for mechanical inoculation were raised from healthy seeds in
earthern pots containing steam sterilized soil and compost and maintained in an insect proof glass
house for recording observations of symptom development.
III. RESULTS AND DISCUSSION
Data on survey revealed that the natural incidence of the necrosis disease ranged from 35-47 % and
10-16 % in Kharif and Rabi seasons respectively.
Field grown sunflower plants showed initial symptoms of necrosis 25-30 days after sowing.
The disease was found to infect the sunflower on all the stages starting from seedling to maturity
(Nagaraju and Hanumantha Rao, 1999). Virus Isolate-N was seen to impart chlorotic specks, which
is the initiation of necrotic spots. The necrotic spots later coalesce and extended to leaf veins
causing veinal necrosis. On stem, infection appeared in the form of light brown stripes which later
became dark brown and bigger in size leading to stem necrosis and flaccidity of leaves. Severely
infected leaves dried and finally dropped down. Concentric ring spots, oak leaf pattern and upward
curling of leaf margins were also evident. Infected plants remained stunted as compared to healthy
plants. The infection on stem extended downward from petiole base. Lastly the necrosis appeared
on sepals. Plant dies when infection occurred in seedling stage. If plants get infected at older age,
the flower remained free from infection. Earheads of infected plants remained small in size and bear
less, small and shriveled seeds with whitish streaks. Sap inoculated plants of sunflower cv. Cargil
under glass house condition also produced symptoms identical to the field infected sunflower.
Occurrence of necrosis was confined mainly to Kharif season.
Initial symptoms recorded of Isolate-Y were faint chlorotic specks which later spread all over
the leaf surface exhibiting a bronzed appearance. The infected plants remained stunted and plants
infected at the early stage showed discoloration of floral calyx and malformation of flowering head.
Yellowing symptoms were commonly observed in Rabi season. Oak leaf pattern on infected leaf
was also observed. In some case, the infected leaves dried within 4-5 days as a result of intensive
tissue necrosis from the tip towards the petiole base. From petioles the infection moved to the stem
and produced necrotic streaks. The noticeable symptoms on the sap inoculated plants of sunflower
International Journal of Applied and Pure Science and Agriculture (IJAPSA)
Volume 01, Issue 11, [November - 2015] e-ISSN: 2394-5532, p-ISSN: 2394-823X
@IJAPSA-2015, All rights Reserved 73
with Isolate-Y included unevenly distributed chlorotic specks, curling, narrowing and distortion of
leaves imparting a malformed bushy appearance to plant. Flower heads of such infected plants
failed to develop and open.
Initiation of chlorotic specks Necrotic spots initiation
Flaccidity of veins and petiols
Symptoms caused by Isolate- N
Plant necrosis
Necrosis at flowering stage
International Journal of Applied and Pure Science and Agriculture (IJAPSA)
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IV. CONCLUSION
Sunflower necrosis disease is an emerging threat for sunflower production system in southern
India. Among the virus diseases of sunflower, necrosis disease has gained importance because of its
heavy devastating nature in most of the sunflower growing states in India. On the basis of
symptomatology on sunflower, the virus isolates causing diseases characterized by necrosis and
yellowing respectively have been tentatively identified as two different strains of Tobacco Streak
Virus. Considering the importance of yellowing and necrosis disease in sunflower, the study has
much relevance and hence will be a stepping stone to etiological aspects of virology
V. ACKNOWLEDGEMENT
The author is highly thankful to Department of Plant Pathology, College of Agriculture,
Marathwada Agricultural University, Parbhani, Maharashtra, India for providing necessary facilities
for the conduct of research work.
Earhead infection Whitish streaks on seeds
Yellowing symptom on sunflower plants
Symptoms caused by Isolate- Y
Healthy Healthy Diseased Infected
International Journal of Applied and Pure Science and Agriculture (IJAPSA)
Volume 01, Issue 11, [November - 2015] e-ISSN: 2394-5532, p-ISSN: 2394-823X
@IJAPSA-2015, All rights Reserved 75
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