Major Viral Diseases of field crop in Meghalaya

1. PRESENTATION ON
MAJOR VIRAL DISEASES OF FIELD
CROPS IN MEGHALAYA WITH
MANAGEMENT PRACTICES
SUBMITTED BY:
1. Alvaliza Nongrum- CAU/CPGS/B17/01
2. Bablu Hrangkhawl (Leader) - CAU/CPGS/B17/02
3. Fivalyne War – CAU/CPGS/B17/04
Course No. : PP-363

2. INTRODUCTION: VIRAL DISEASES
Viruses are intracellular (inside cells) pathogenic
particles that infect other living organisms.
Plant viruses and viroids are diverse and unusual
groups of plant pathogens that infect and
cause disease in many crop plants.
Viruses are obligate parasites; that is, they
require a living host in order to grow and
multiply.
Viruses can often spread through vegetative
propagation and by vectors like Aphids, White Fly.

3. Group: Group IV ((+)ssRNA)
Family: Luteoviridae
Genus: Polerovirus

4. Potato Leaf Roll Virus (PLRV)
PLRV was first described by Quanjer et
al. in 1916.
PLRV is transmitted by aphids, primarily
the green peach aphid, Myzus persicae

5. ECONOMIC IMPORTANCE OF PLRV

6. SYMPTOMS OF PLRV
Primary Infection
Starts with
younger leaves
Leaf margins
become
necrotic, turning
brown and
purplish and curl
inwards towards
the centre of the
leaf
Secondary Infection
Starts from
infected potato
culls, produces
more severe
symptoms
Entire leaf
can become
chlorotic and
sometimes
also has a
purple
discoloration.

7. SYMPTOMS OF PLRV
• Necrosis of the phloem tissue
particularly in the haulm is
observed after onset of symptoms.
• Appearance as small brown spots
scattered throughout the tissue.
• Plants infected with PLRV experience stunted growth and
produce smaller tubers. Infected tubers retain normal
shape but experience necrosis of the vascular tissue.
• This symptom is caused by the selective death and damage
to cells in the vascular tissues of the tuber.

8.  Reducing aphid populations
 Systemic and foliar insecticides can be used to prevent
aphid feeding.
 Imidacloprid, Methamidophos and Endosulfan are
commonly used in aphid control.
 Sanitation: Cleaning any volunteer tubers from a field
reduces any reservoirs that may persist
 Seed Certification programs test seed lots utilizing
ELISA for the detection of multiple potato viruses.

9. MUNGBEAN YELLOW MOSAIC
VIRUS
Common name : Yellow Mosaic Virus
Kingdom:Shotokuvirae
Phylum: Cressdnaviricota
Class: Repensiviricetes
Order: Geplafuvirales
Family: Geminiviridae
Genus: Begomovirus
Species: Mungbean Yellow Mosaic Virus

10. Mungbean Yellow Mosaic Virus
A new isolate (Mg-mungbean-1) of yellow
mosaic was identified in Meghalaya
It is transmitted by white fly (Bemesia tabaci)
Decrease in the seed yield to about 80%

11. SYMPTOMS
 Irregular green and yellow
patches in older leaves and
complete yellowing of younger
leaves
 Soon it develops into a bright
yellow mosaic or yellow mosaic
symptoms
 Infected leaves shows necrotic
symptoms
 Severe stunning of plants and
deformed pods

12. MANAGEMENT
 Rogue out the diseased plants up to 40 days
after sowing.
 Remove and destroy the infected plants.
 Remove the weed hosts periodically.
 Use increased seed rate (25 kg/ha)
 Apply neem oil @0.3% to control white fly.

13. Kingdom: Orthornavirae
Phylum: Kitrinoviricota
Class: Alsuviricetes
Order: Martellivirales
Family: Closteroviridae
Genus: Closterovirus
Species: Citrus Tristeza Virus
CITRUS TRISTEZA VIRUS

14. CITRUS TRISTEZA
VIRUS
 The term “tristeza”, in Portuguese meaning “sadness” or
“melancholy”, refers to the decline seen in many citrus species
when grafted on Citrus aurantium (sour orange) or Citrus limon
(lemon) rootstocks.
 CTV probably originated in Malaysia and other countries of
Southeast Asia.
 CTV is transmitted by Aphid
 In Meghalaya, it is most important and
severe disease of Khasi Mandarin.

15. IMPORTANCE OF CTV
Citrus Tristeza Virus (CTV) causes one of the most
damaging diseases of citrus, devastating epidemics of
which have changed the course of the citrus industry.
CTV is the most economically important and damaging
virus of citrus trees. It can be spread quickly and do
damage not only by killing trees with sour orange
rootstock, but also by stem pitting normal citrus trees.

16. SYMPTOMS OF CTV
• One of the most economically
significant outcomes of CTV
a bud union disease
which is characterized by the
decline of trees.
• Trees that decline slowly generally
have a bulge above the bud union, a brown line just at the point of
bud union, and inverse pinhole pitting (honeycombing) on the inner
face of sour orange rootstock bark.
• Stunting, leaf cupping, vein clearing, chlorotic leaves, stem pitting
and reduced fruit size are common symptoms observed on
susceptible hosts.

17. CTV Symptoms
• Stem pitting may sometimes cause a
bumpy or ropy appearance of the trunks
and limbs of adult trees, deep pits in the
wood under depressed areas of the bark,
and a reduction in fruit quality and yield.
• Seedling Yellow Syndrome is
characterized by stunting, production of
chlorotic or pale leaves, development of
a reduced root system, and cessation of
growth of trees grafted on sour orange,
grapefruit and lemon seedlings
cultivated under greenhouse conditions
(20–26°C).

18. MANAGEMENT OF CTV
 Quarantine is the best management strategy
 Using citrus rootstock species that induce tolerance to
the Tristeza disease
 Planting virus-free trees by shoot-tip grafting or heat
treatment is very important.
 A biological approach has been to bring in a parasitoid
wasp from Asia that naturally controls A. spiraecola.
 To effectively manage the stem pitting disease some
citrus industries have adopted a strategy of
prophylactically inoculating trees with mild strains of
CTV otherwise known as cross-protection

19. Family: Geminiviridae
Genus: Begomovirus
Species: Urdbean
Leaf Crinkle Virus

20. INTRODUCTION
 Urdbean leaf crinkle virus caused urdbean leaf crinkle
diseases is urdbean
 It is transmitted by whiteflies, aphids
 It is also transmitted through grafting

21. ECONOMIC IMPORTANCE
Urdbean leaf crinkle diseases is an economically significant
widespread and devastating diseases resulting in ectreme crinkling ,
puckering of leaves
It reduce the yield in major urdbean producing area
The loss in seed yield is from 35-80%

22. SYMPTOMS
• Initial symptoms are generally an
increase in the size of the third trifoliate
leaf and a lighter green colour.
• Approximately 1 week later, a typical
crinkling becomes more conspicuous.
• Affected leaves become coarse and
leathery.
• Plants infected late as a result of field
spread have symptom-free lower
leaves.

23. MANAGEMENT PRACTICES
 Remove and destroy the infected plants
 Use diseases free seeds
 The crop field should be weed free initially for 3-4 weeks
by following timely hoeing and weeding by power hand
tiller and/or hand tools at 20 and 35 days after sowing.
 Mulches like straw hay, plastic, etc. should be used in
between the rows to suppress the weed growth.
 increased seed rate (25kg/ha)
 Hot water treatment of the seeds at 550°C for 30
minutes

24. Kingdom: Orthornavirae
Phylum: Pisuviricota
Class: Stelpaviricetes
Order: Patatavirales
Family: Potyviridae
Genus: Potyvirus
Species: Papaya Ring Spot
Virus

25. HISTORY AND ORIGIN OF
PRSV
Using genetic phylogeny studies, researchers suspect the virus
originated in Asia, likely India, about 2,250 years ago.
From there it slowly spread through the continent reaching China about
600 years ago.
It was also introduced directly from India to Australia and the Americas within
the last 300 years.
Papayas were introduced to India only 500 years ago, at which point the virus
made the jump from cucurbits.

26. PRSV infection in 38 of 53 papaya samples collected from
surveyed locations(Ri-Bhoi district) with an average
incidence of 71.7%.
It causes around 80-85% losses.

27. • Leaves are molted and distorted
with blisters and have rings.
• In infected leaves, the lamina is
reduced and malformed and are
often modified into tendril like
structures giving a shoestring
appearance.
• Water soaked chlorotic spots on
tender stem and petioles
• Severe conditions- older leaves
fall down and a small tuff of
younger leaves are left at the top
in upright position.

28.  Plants are stunted and fruit set is reduced.
 Fruits develop innumerable circular, water soaked spots with
concentric rings.
 Sometimes fruit size is reduced with deformed shape.

29. • Cultural method: Use of Disease free seedlings raised
in net houses or polyhouses
• Roughing: Removal and destruction of diseased plants.
• Netting: To prevent insect vectors from spreading the
virus
• Transgenic: Grow transgenic varieties like Sun Up and
Rainbow
• Cross protection: A mild strain of PRSV is introduced
into the host plant, which then develops resistance to
virulent strains of the virus. Development of cross-
protection in papaya was researched in Hawaii starting
in 1979

30. Kingdom: Orthornavirae
Phylum: Pisuviricota
Class: Stelpaviricetes
Order: Patatavirales
Family: Potyviridae
Genus: Potyvirus
Species: Potato virus Y

31. Potato Virus Y
• Potato virus Y (PVY) is an aphid-
borne virus that causes yield
losses and tuber quality defects
in commercial potato crops.
• Transmitted by aphids including
green peach (Myzus persicae)
and potato (Macrosiphum
euphorbiae) aphids, as well as
other species that migrate
through the crop.

32. ECONOMIC IMPORTANCE
When potato plants become infected early, yield losses of 10-80%
have been reported. Losses can be due to small and few tubers
being produced.
The severity of symptoms and magnitude of yield depends on the
time of infection, number of plants infected, strain of the virus and
the variety grown.
In seed crops PVY infection increases the risk of the seed lot being
downgraded or rejected from certification. PVY infects other
solanaceous crops including tomato and capsicum.

33. • Leaf symptoms can range from
mild to severe mosaic or
mottling. In severe cases leaf
drop can occur. Infected plants
are often stunted.
• Tubers from infected plants are
often small and can have necrotic
or dead rings on the skin.
Symptoms of infection vary with cultivar, plant
age, environmental conditions and PVY strain.

34. Potato Virus Y

35. MANAGEMENT
 To minimise PVY spread in potato crops an Integrated
Disease Management approach is necessary
 The most important management practice is to use seed
lots with zero levels of PVY.
 Use PVY resistant potato varieties when available.
Commercial varieties used in WA that are resistant to
PVY are Royal Blue, FL1867 and FL2195.
 Plant a non-host border crop around the potato crop
about four weeks before planting, for example, wheat,
oats, sorghum..
 Remove any potato plants showing virus symptoms –
removing virus sources within the crop may help to slow
down the spread of the virus to nearby plants especially
early in the season.

36. MANAGEMENT
 Employ good hygiene practices. Use 1:4 dilution of
household bleach or 1% Virkon to wash equipment
and machinery.
 Remove and destroy old potato crops immediately
after the final harvest to minimise virus spread to
new crops.
 Destroy volunteer potato plants and weeds before
planting to reduce any potential virus and aphid
sources for new crops.
 Mineral oils have been used overseas to limit PVY