Pepper Mottle Virus

Pepper Mottle Virus

Aphid-Transmitted Potyvirus

Found in tropical and sub-tropical regions, notably in
Central America, Florida, and India
World Vegetable Center

Symptoms
Symptoms include mottle and puckering of leaves, and
misshapen leaves and fruit. Symptomatic leaves are
not as chlorotic as those infected with alfalfa mosaic
virus (AMV). Heavily infected plants may be stunted
and fruit yields reduced. Foliage and fruit symptoms
are less severe in plants that are infected at a later
stage of development.
The virus may occur in mixed infections with other
related viruses such as potato virus Y (PVY), tobacco
etch virus (TEV) or pepper veinal mottle virus (PVMV).

Conditions for Disease Development
Pepper mottle virus (PepMV) is transmitted by aphids
such as green peach aphid (Myzus persicae), cotton
melon aphid (Aphis gossypii), and cowpea aphid (Aphis
craccivora) from infected host plants, which are often
weeds such as Datura spp. and nightshade.
An aphid gets the virus by feeding on an infected
plant for only a few seconds. The aphid can then transmit
the virus immediately the next time it bites into a plant,
then losing the virus. The virus is generally retained by
the aphid for no more than one hour.
The virus also may be introduced into pepper crops
on infected transplants, and then spread by aphids to
nearby weeds, which act as future reservoirs for the
virus.
PepMV is mechanically-transmitted by plant sap
but not by simple contact between plants. PepMV can
be transmitted by grafting but not by pepper seed.

Control
Resistant varieties are available. Check with your
extension agent for resistant cultivars that are available
in your region.
Use of insecticides during the growing season is
ineffective; however, control of aphids early in the season
prior to seeding or planting the field, to reduce initial
infection and spread, may be useful. Spray weeds
bordering the field with an aphicide prior to seeding or
planting the field. This will prevent the aphids from moving
to other plants and infecting them when subsequent
weed control is started. Destroy all annual weeds in
the field, including those in ditches, hedge or fencerows,
and other locations.Use a 32-mesh or finer mesh netting to exclude
aphids from transplants before they are set into the
field. Avoid planting peppers close to established
tomato, tobacco, and pepper fields since these fields
may harbor aphids. Plant earlier to avoid high aphid
populations that occur later in the season.
Other control measures include scouting fields for
the first occurrence of virus disease. Where feasible,
infected plants should be pulled up and destroyed, but
only after spraying them thoroughly with an insecticide
to kill any insects they may be harboring.
Reflective mulches may be used to repel aphids,
thereby reducing the rate of spread of aphid-borne
viruses. Aphid populations should be monitored early
in the season and mineral oil or other insecticide
treatments applied when needed. The mineral oil sprays
will reduce the frequency of transmission of the virus
by the vector and thereby delay development of the
disease in the pepper crop.

Cucumber Mosaic Virus

Cucumber Mosaic Virus

Aphid-Transmitted Cucumovirus

Found worldwide:World Vegetable Center

Symptoms
Symptoms vary widely. One of the most common
expressions is a severely stunted, nonproductive plant
that has dull light green foliage with a leathery
appearance but not distinctive foliar markings.
In some cases the leaves become narrow and no
longer expand, while in other cases, small necrotic
specks or ring spots with oak leaf patterns develop.
Sometimes a necrotic line develops across the leaf.
Affected leaves may drop prematurely. Older plants that
are infected may show foliar mottling or no symptoms
on foliage or fruit. Fruit may be wrinkled, bumpy, pale to yellowish
green in color, sometimes with sunken lesions. On
some varieties lines or ring spots may develop.

Conditions for Disease Development
Cucumber mosaic virus (CMV) is not transmitted
through pepper seed. CMV can be mechanically
transmitted but because it is not as stable as TMV,
workers handling infected pepper plants do not as
readily transmit it.
More than 80 species of aphids including the green
peach aphid, Myzus persicae, are an vector of CMV;
weeds are hosts for the virus as well as for the aphid
vectors. The large number of aphid vector species and
natural host reservoirs accounts for the high incidence
of CMV in field plants.
Aphid vectors can acquire and transmit the virus
after feeding for only one minute, but the ability to
transmit it declines quickly. Pepper is not a preferred
host of the green peach aphid, which normally prefers
to feed on cucurbits and other plants. Most epidemics
occur when aphids feed early in the season on weeds
that may be symptomless but serve as reservoirs for
the primary virus inoculum, and then later the virusbearing
aphids colonize the pepper plants.

Control
Pepper varieties resistant to some strains of CMV exist.
Check with your extension agent for resistant varieties
that are available in your region.
Current control measures for CMV are mainly
preventive due to the wide host range of the virus and
the numerous aphid vectors. Vegetable seedlings, other
than pepper, derived from CMV-infected seeds can also
serve as potential primary sources of virus. The use of
virus-free seeds together with the eradication of virus
reservoirs such as volunteer plants and nearby weeds
can be effective in controlling CMV.
Grow seedlings in a structure or seedbed protected
with netting of mesh size of 32 or greater to prevent
aphids from entering. Discard any seedlings or young
plants that show virus symptoms. Do not touch other
seedlings while discarding them. Avoid touching or
handling plants prior to setting them in the field. Dip
hands in milk while handling plants. Do not clip or
damage young seedlings since this increases the
possibility of mechanical transmission of the virus from
contaminated tools or hands. Remove diseased plants
from the field as soon as virus symptoms are noticed.
This will reduce the spread of the virus by aphid vectors.
Disinfect tools, stakes, and equipment before moving
from diseased areas to healthy areas. Hands and tools
may be washed with soap or milk. Work in diseased
areas last, after working in unaffected parts of a field.
Insecticide sprays that are not fast-acting may not
be that effective because the aphids move to other
nearby unsprayed plants when disturbed.
If feasible, plant either very early or very late in the
season to avoid exposing young plants to high or
migratory aphid populations. Prevent aphids from
reaching the pepper crop by covering the planted area
with fine 32-mesh nylon net.
Other less effective measures include: planting
barrier crops that are not susceptible to CMV such as
corn, applying sticky traps, or covering the ground with
an aphid deterrent material like aluminum foil strips.
Another control strategy is to grow trap crops nearby
that attract aphids and then spray these plants with a
contact insecticide to destroy the aphid populations.
Also, spray the pepper crop with mineral oil to delay
virus spread in the field by interfering with aphid
transmission of the virus.

Chilli Veinal Mottle Virus

Chilli Veinal Mottle Virus

Aphid-Transmitted Potyvirus

Found in many Asian countries

Symptoms
Leaf mottle and dark green vein-banding are the most
characteristic symptoms. Leaves of some cultivars are
smaller and distorted. Symptoms are most obvious on
the younger, smaller leaves.
Plants infected when young become stunted and
have dark-green streaks on their stems and branches.
Most of their flowers drop before fruit formation. A few
mottled, distorted fruit may be produced. Such
symptoms contribute to significant yield losses.

Conditions for Disease Development
Chilli veinal mottle virus (ChiVMV) is transmitted by
several species of aphids: green peach aphid, Myzus
persicae; cotton melon aphid, Aphis gossypii; cowpea
aphid, Aphis craccivora; green citrus or spirea aphid,
Aphis spiraecola; corn leaf aphid, Rhopalosiphum
maidis; citrus brown aphid, Toxoptera citrida; and rusty
plum aphid, Hysteroneura setariae.
An aphid gets the virus by feeding on an infected
plant for only a few seconds. The aphid can then transmit
the virus immediately the next time it bites into a plant,
then losing the virus. The virus is generally retained by
the aphid for no more than one hour. Winged aphids of
the above species are the most likely to spread the
virus to other pepper plants and are the most difficult to
control. The virus is also transmitted mechanically and
by grafting, but not by seed.

Control
Resistant/tolerant plant material is available from
– The World Vegetable Center, Taiwan.

Grow transplants in a nethouse or cover seedbeds
with a 32-mesh or finer mesh net to prevent introduction
of aphids. Use yellow sticky traps to monitor and to
reduce aphid populations.
Avoid touching or handling pepper plants prior to
setting them in the field. Remove any diseased
seedlings that show symptoms of the disease and place
them in a refuse pile away from pepper production fields.

Alfalfa Mosaic Virus

Alfalfa Mosaic Virus

Aphid-Transmitted Bacilliform Virus
Found : worldwide World Vegetable Center

Symptoms

The foliage has a distinct bright yellow to white mosaic
that sometimes causes large areas of interveinal leaf
tissue to be bleached in appearance. Chlorotic line
patterns and veinal necrosis also may occur. Generally,
the leaves are not distorted in shape. If infected when
young, the plants may be stunted and their fruit will be
misshapen.it as quickly, but the aphid actually retains the virus for
only a short period of time. The virus is also readily
transmitted mechanically and by grafting.
Conditions for Disease Development

Alfalfa mosaic virus (AMV) is found most commonly in
pepper crops that have been planted near alfalfa, clover
or other legumes. It is generally considered to be a
minor threat to pepper production.
Transmission by seed is the primary means of
establishment of the virus while aphid transmission is
more important for the subsequent spread in field
plantings. AMV is transmitted by many species of
aphids including the green peach aphid, Myzus
persicae. The aphid can acquire the virus by feeding on
an infected plant for less than a minute and can transmit

Control
Pepper varieties resistant to AMV are not available.
Various control measures are required because
AMV is transmitted by seed, aphids, and mechanically.
Control measures must take into account the disease’s
wide host range (alfalfa, pepper, tomato, tobacco, potato,
clover, many cucurbits and beans, and several other
crops and weeds) and numerous aphid vectors.
Use virus-free pepper seed. Check transplants for
any symptom development and discard those with
symptoms. One or two transplants on either side of
the affected plants should also be discarded. Avoid
touching or handling healthy plants after handling plants
suspected of virus infection. Wash hands with soap
afterwards or use disposable gloves when handling
infected plants.
AMV-infected vegetable seedlings are potential
primary sources of the virus. Cover seedlings with mesh
size of 32 or higher to prevent aphids. Do not clip or
damage young seedlings since this increases the possibility
of mechanical transmission of the virus from
contaminated tools or hands.
Aphid control may be difficult because the virus is
transmitted very rapidly by these insects. Use fastacting
insecticide sprays since aphids may move to
other nearby unsprayed plants when disturbed.
Disinfect tools, stakes, and equipment before moving
from diseased areas to healthy areas. Work in diseased
areas last, after working in unaffected parts of a field.
Other less effective measures include: planting
barrier crops that are not susceptible to AMV such as
corn, applying sticky traps, or covering the ground with
an aphid deterrent material like aluminum foil strips.
Another control strategy is to grow trap crops nearby
that attract aphids and then spray these plants with a
contact insecticide to destroy the aphid populations.
Also, spray the pepper crop with mineral oil to delay
virus spread in the field by interfering with aphid
transmission of the virus.