Plant Virus Diseases: Research Approach and
Current Activities at Plant Pathology Division
S. Joshi, RD. Timila and BN. Mahto
Plant Pathology Division
Nepal Agricultural Research Council
(NARC), Khumaltar, Nepal
Contents
 Introduction
 Survey
 Detection and diagnosis of seedborne viruses
 Host resistance
 Seed Cleaning for virus free lot
 Current research activities
Introduction
 Virus diseases are one of the major constraints
for higher production of crop plants
 Heavy losses in yield of crop plants
due to
viruses especially in vegetables
 Combined infestation of
more than two
viruses at time in a particular crop
 The incidence and severity of different virus
diseases on different crops are in increasing
trend.
Introduction (contd.)
 Economic yield losses in various crops are
not known
 Sometimes 100% yield loss was observed in
Zucchini crop
 Farmers experiences more than 90% yield
losses in cucumber, other cucurbits and
tomato crops
 Virus disease management particularly in
vegetables and leguminous crops are most
essential
Survey of Virus
Diseases
Tomato yellow leaf curl virus
in tomato and pepper
 TYLCV is a serious problem in
tomato and chilli especially in
terai and foothills (Joshi et. al.
1996).
 The incidence ranged from 5 to
70% in tomato and 20-80% in
pepper.
 (c-DNA hybridization test at
AVRDC, Taiwan and University of
Wisconsin, USA) showed 42% of
tomato samples positive to
Indian probe of TYLCV
TYLC
Virus Diseases in Pepper
 Cucumber mosaic virus (CMV) and Chilli veinal mottle




virus (CVMV) are widely spread disease in pepper
cultivated areas.
CVMV mostly recorded in the mid hills
CMV and CVMV were identified by Double Antibody
Sandwich ELISA (Antiserum and IgG were provided by
AVRDC).
Tomato yellow leaf curl virus (TYLCV) reported in
chilli growing areas (diagnosed with c-DNA
hybridization)
57% of pepper samples showed positive reaction to
Indian probe of TYLCV and 17% to Thai probe.
Cucurbits virus complex:
 Complex infection of CMV, ZYMV, WMV 1 and 2,
SqMV, CGMMV found in Zucchini squash and
cucumber
 Wide spread in the mid hills of Nepal
 CMV reported in most of the cucumber growing
areas
Virus Diseases of Zucchini
The tested zucchuni
plants were found to
be infested by ZYMV
and WMV1
Mungbean Yellow mosaic virus (MYMV)
 MYMV observed as a severe threat in Mungbean,
blackgram and soybean in terai and inner terai of
Nepal
 MYMV also detected in horsegram and pigeon
pea
Detection and
diagnosis of seedborne viruses in
some legumes
Pea seed-borne mosaic virus (PSbMV) in Lentil
Lentil
 Lentil seed samples tested at different
time
intervals were observed to be infested with
PSbMV (Joshi et. al. 1993 and 2004).
Detection Method:
 Growing-on
test followed by DAC ELISA
Indicator plant assay:
 Infection ranged from 0.5 to 12.7%
Pea seed-borne mosaic virus (PSbMV)
Broad bean seed
samples were also
found to be infested
with PSbMV
Infection
ranged
from 3.8 to 7.8%.
(Joshi et.al.,1993)
Bean common mosaic virus
Bean
common
mosaic virus was
detected in seed
samples
of
blackgram
Infection
ranged
from 0.6 to 2.5%
Host Resistance
Screening tomato genotypes against TLCV:
Out of 19 genotypes , Thirteen were found
resistant under artificial inoculation
condition through viruliferous whiteflies
(Bemicia tabaci) under screen house
On field condition at Sarlahi, ATY2, ATY4,
ATY6 , Fiona, TY Gold lines of tomato
were found resistant
while at Nepalgunj, all the above lines were
found susceptible.
.
Screening Pepper against CMV and CVMV
Under screen house condition:
 Pepper genotypes, P- 3, Perennial HDV, PSP 11,
Tiwari 2, and LV 2722 were observed resistant to
local isolate of CMV
 Local cultivars of pepper from Bhaktapur, HAD
832, Huareu (Hybrid) and Toom were resistant to
local isolate of CVMV.
Screening Mungbean genotypes against
Mungbean yellow mosaic virus
 Out of 15 genotypes, three lines, VC 6370, VC
6369, VC 6370 (21-16) were found resistant at
Rampur
 Almost all the lines were resistant at Sarlahi
conditions a tarai district of Nepal
 Two resistant genotypes have been released for
cultivation as a varieties in the name of
Pratikchya and Kalyan.
Cucumber Seed
Cleaning for CMV free
state
 Seed
samples collected from
hilly districts (during 2004 and
2005)
 Growing
on test followed by
ELISA for detection
 CMV
was detected in 40%
seed samples tested
of
Cucumber seed Cleaning for CMV free state
 The extent of infection
ranged from 2 to 80 %.
 No infection was found
in the seed samples
tested during 2005,

 Seed
samples
were
produced from seed lot
sorted free of infection
during 2004 test.
Current Research
Activities
Current research activities focuses on
 Survey of plant virus diseases
 Identification
and preservation of
identified virus (long term preservation
on host plant and dry preservation)
 Testing of different antiviral products
and botanicals for management of
cucurbits virus diseases
Management of Virus Diseases
Use of antiviral products and botanicals
 Spraying of antiviral products like Anti-VS
(Korean), Victovirus, Privintal, Viricon
 Other natural products like cow milk,
 Bougainvillea leaf extract
 Insecticide Oshin before inoculation of virus
was found effective to minimize virus
diseases
 Reduced incidence and severity up to 5 weeks
from the date of first spray (PPD 2013)
Management of Virus Diseases
Significantly higher yield of fruits were
produced by Victovirus, Anti V-S and fresh
Bougainvillea leaf extract in zucchini
squash
Thank you