International Journal of Applied And Pure Science a nd ......General Impact Factor (GIF): 0.875 Scientific Journal Impact Factor: 1.205 International Journal of Applied And Pure Science

General Impact Factor (GIF): 0.875

Scientific Journal Impact Factor: 1.205

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)

Volume 01, Issue 11, [November - 2015] e-ISSN: 2394-5532, p-ISSN: 2394-823X


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




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




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




BIBLIOGRAPHY

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