Viruses that have occurred naturally in agronomic and vegetable crops in Florida

Material Information

Viruses that have occurred naturally in agronomic and vegetable crops in Florida
Series Title:
Extension Plant Pathology Report no. 7
Translated Title:
Plant Protection Pointers PPP 7 ( English )
Kucharek, Tom
Purcifull, Dan
Hiebert, Ernest
University of Florida -- Florida Cooperative Extension Service -- Department of Plant Pathology -- Institute of Food and Agricultural Sciences
Place of Publication:
Gainesville, Fla
Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date:


Subjects / Keywords:
North Florida ( local )
Tomatoes ( jstor )
Viruses ( jstor )
Cucumovirus ( jstor )
Spatial Coverage:
North America -- United States of America -- Florida


Florida Historical Agriculture and Rural Life

Record Information

Source Institution:
Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location:
Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.


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University of Florida

Plant Protection Pointers


By Tom Kucharek, Dan Purcifull, and Ernest Hiebert

Viral diseases of plants occur commonly in Florida. Some viral diseases have impacted on crop production
by reducing yield or quality while other viral diseases in Florida have not had notable effects in this regard.
However, potential exists for future epidemics caused by those quiescent or "silent" viruses. The purpose of
this publication is to present information about viruses that have occurred NATURALLY in Florida in
agronomic and vegetable crops. It is possible that viral diseases not presented herein have occurred in Florida.
Virus listings within this publication are based upon published reports, or communications with other scientists,
and on our unpublished data.

No attempt is made herein to list complete host ranges of the viral diseases found in Florida. Host range
studies done by artificial inoculation in the greenhouse have been numerous and useful but such tests are not
necessarily representative of natural infections or epidemics. For example, tobacco mosaic virus is infective
in hundreds of plant species but this virus has been of consequence in only a few crop species in Florida. Also,
watermelon mosaic virus 2 has an extensive host range, but none of the noncucurbitaceous experimental host
species have been related to the epidemics in squash or watermelons grown in Florida. On the other hand,
epidemics of papaya ringspot virus Type W (formerly named watermelon mosaic virus 1) have been traced to
nearby cucurbitaceous weeds such as balsam apple and creeping cucumber.

The ultimate purpose of attaining a diagnosis, it seems to us, is to provide a foundation for selection of
possible control tactics. For example, lettuce mosaic virus is controlled by not planting seed lots that have been
identified to contain lettuce mosaic virus. However, even with an accurate diagnosis of some viral diseases,
control is not possible because the diagnosis is too late or control measures are not available. Again, let us
compare the situation between watermelon mosaic viruses 1, papaya ringspot virus type W and watermelon
mosaic virus 2. Papaya ringspot virus type W predominates in south to central Florida where creeping
cucumber and balsam apple flourish as weeds. Eliminating these two weeds around the field with the cucurbit
crop will aid significantly in controlling this viral disease. Watermelon mosaic virus 2, on the other hand,
becomes destructive in some years and it can not be controlled because the primary source of the virus has not
been identified. The reader should realize that although not all viral diseases are controllable at the present
time, some viral diseases in Florida have been controlled or eliminated from an area with resistant varieties,
seed indexing, vector control, sanitation practices or other cultural manipulations.



Introduction ................... ...................................... 1

Naturally occurring viruses found
in agronomic and vegetable crops in Florida ................................. 3

Basic information about some viruses found in Florida ........................ 11




New Zealand spinach (Tetragonia expansa) Cucumber mosaic virus (one time)


Chives (Allium schoenoprasum) None

Garlic (Allium sativum)

Leeks (Allium porrum)

Onion (Allium cepa)

Shallots (Allium ascalonicum)

Malanga (Xanthosoma c

Taro or Dasheen (Coloc

Ginseng (Panax spp.)

Borage (Borago officina

Comfrey (Symphytium s

Unknown virus(s)


Cucumber mosaic virus (one time)



;aracu) Dasheen mosaic virus

asia esculenta) Dasheen mosaic virus




lis) None

pp.) None


Broccoli (Brassica oleracea var botrytis) None

Brussels sprouts (Brassica oleracea var gemmifera) None

Cabbage (Brassica oleracea var capitata) Cabbage leaf curl virus

Cauliflower (Brassica oleracea var botrytis) None

Chinese cabbage types

Collards (Brassica oleracea var acephala)

Kale (Brassica oleracea var acephala)

Kohlrabi (Brassica caulorapa)

Mustard greens (Brassica juncea)

Radish (Raphanus sativus)

Rutabaga (Brassica napobrassica)

Turnip (Brassica rapa)

Water cress (Nasturtium officinale)


Turnip mosaic virus



Turnip mosaic virus



Turnip mosaic virus



Beets (Beta vulgaris) Cucumber mosaic virus (one time)

Spinach (Spinacia oleracea) Cucumber mosaic virus (one time)

Swiss chard (Beta vulgaris var cicla) Cucumber mosaic virus (one time)


Dandelion (Taraxacum officinale) None

Endive (Cichorium endivia) Bidens mottle virus
Lettuce mosaic virus
Escarole necrosis (Tobacco streak virus)

Escarole (Cichorium endivia) Bidens mottle virus
Lettuce mosaic virus
Escarole necrosis (Tobacco streak virus)

Lettuce (Lactuca sativa) Bidens mottle virus
Big vein virus
Cucumber mosaic virus (only on Cos types)
Lettuce mosaic virus
Sonchus yellow net virus
Spring yellows virus
Escarole necrosis (Tobacco streak virus)

Salsify (Trapopogon porrifolius) None

Sunflower (Helianthus annuus) None


Tarragon (Artemisia dracunculus) None


Sweet potato (Ipomea batatas)

Cucumber mosaic virus (one time)
Feathery mottle virus
Internal Cork virus



Cantaloupe (Cucumis melo)

Cucumber (Cucumis sativus)

Squash & Pumpkin (Cucurbita spp)


Trichosanthes (Trichosanthes dioica)

Watermelon (Citrullus lanatus)

Cassava (Manihot esculenta)

Chaya (Cnidoscolus acontifolius)

Cucumber mosaic virus
Squash mosaic virus
Papaya ringspot virus type W
Watermelon mosaic virus 2
Zucchini yellow mosaic virus

Cucumber mosaic virus
Papaya ringspot virus type W
Watermelon mosaic virus 2
Zucchini yellow mosaic virus

Cucumber mosaic virus
Papaya ringspot virus type W
Watermelon mosaic virus 2
Zucchini yellow mosaic virus

Papaya Ringspot virus type W
Unnamed potexvirus

Unnamed potexvirus

Papaya Ringspot virus Type W

Watermelon mosaic virus 1
Zucchini yellow mosaic virus
Unnamed Potyvirus



Cassava common mosaic



Alyce clover (Alysicarpus vaginalis)

Alfalfa (Medicago sativa)

Beans, green (Phaseolus vulgaris)

Beans, lima (Phaseolus limensis)

Beans, butter (Phaseolus lunatus)

Hairy indigo (Indigofera hirsuta)

Lupine (Lupinus spp.)

Macroptilium (Macroptilium lathyroipes)

Peas, English (Pisum sativum)

Peas, southern (Vigna unguiculata)

Peanut (Arachis hypogaea)

Red clover (Trifolium pratense)

Siratro (Macroptilium atroprupureum)
Also, see Macroptilium above.

Soybean (Glycine max)

Blackeye cowpea mosaic or related virus
Peanut mottle virus
Peanut stripe virus
Watermelon mosaic virus 2

Alfalfa mosaic virus

Bean common mosaic virus
Bean golden mosaic virus
Bean yellow mosaic virus
Red Node (tobacco streak virus)

Cucumber mosaic virus


Blackeye cowpea mosaic virus
Watermelon mosaic virus 2

Bean yellow mosaic virus
Bidens mottle virus
Cucumber mosaic virus
Peanut mottle (blue lupine)
Watermelon mosaic virus 2

Bean golden mosaic virus

Watermelon mosaic virus 2

Blackeye cowpea mosaic virus
Cucumber mosaic virus

Peanut mottle virus
Peanut stripe virus

Peanut stunt virus
Tomato spotted wilt virus

White clover mosaic virus

Bean common mosaic virus (or a
related strain)

Peanut mottle virus
Peanut stripe virus
Soybean mosaic virus


Sweet clovers (Meliotus alba & M ixdica

White clover (Trifolium repens)

Clover yellow vein virus
Peanut stunt virus
White clover mosaic virus


Barley (Hordeum vulgare)

Corn (Zea mays)

Oats (Avena sativa)

Rice (Oryza sativa)

Rye (Secale cereale)

Sugarcane (Saccharum officinarum)

Sorghum (Sorghum vulgare)

Various pasture, forage and biomass grasses

Triticale (X Triticosecale)

Wheat (Triticum aestivum)


Corn stunt (spiroplasma)
Cucumber mosaic virus (one time)
Maize mosaic virus
Maize rayado fino virus
Maize stripe virus
Sugarcane mosaic virus (Maize dwarf
mosaic virus)

Barley yellow dwarf virus (Red leaf)
Oat mosaic virus (Oat soilbome mosaic

Hoja Blanca

Cucumber mosaic virus (one time)

Sugarcane mosaic virus



Wheat soilbome mosaic virus

Barley yellow dwarf virus
Wheat soilbome mosaic virus


Basil (Ocimum basilicum)

Catnip (Nepeta cateria)

Horehound (Marrubium vulgare)

Lemon balm (Melissa officinalis)

Majoram (Origanum spp)







Mints (Mentha spp)

Oregano (Origanum vulgare)

Rosemary (Rosmarinus officinalis)

Sage (Salvia officinalis)

Savory (Satureja spp)

Thyme (Thymus vulgaris)



Asparagus (Asparagus officinalis) None


Cotton (Gossypium hirsutum) None

Okra (Hibiscus esculentus) None


Sesame (Sesamum indicum) Unknown virus


Rhubarb (Rheum rhaponticu

Eggplant (Solanum melonger

Husk tomato (Physalis pruin

Pepper (Capsicum annuum)

m) None


la) Cucumber mosaic virus (one time)
Tobacco ringspot virus

osa) None

Black pod (Tobacco mosaic virus + tobacco
etch virus)
cucumber mosaic virus
Potato virus Y
Pepper mottle virus

Tobacco etch virus

Tobacco mosaic virus








Potato (Solanum tuberosum)

Tabasco pepper (Capsicum frutescens or annuum)

Tobacco (Nicotiana tabacum)

Tomatillo (Physalis alicekengi)

Tomato (Lycopersicon esculentum)

Tobacco rattle virus (Aster ringspot)
Tomato spotted wilt virus

Potato virus X
Potato virus Y
Potato leaf roll virus (net necrosis,
tuber blotch)
Rugose mosaic virus (Potato virus X and
potato virus Y or Potato virus Y alone)
Spindle tuber (viroid)
Tobacco rattle virus (corky ringspot)
Yellow dwarf virus


Cucumber mosaic virus
Potato virus X
Potato virus Y
Tobacco etch virus
Tobacco mosaic virus
Tomato spotted wilt virus

Tomato mottle virus

Cucumber mosaic virus
Potato virus Y

Pseudo curly top virus
Tobacco etch virus
Tomato double virus streak (tobacco mosaic
virus + potato virus X)
Tomato fruit mottle (tobacco mosaic virus
+ potato virus Y)
Tomato mosaic virus (tobacco mosaic virus)
Tomato mottle virus
Tomato spotted wilt virus
Tomato yellows virus


Anise (Pimpinella anisum)

Carrot (Daucus carota var sativa)


(Apium carota var rapaceum)

Celery (Apium graveolens var dulce)

Cucumber mosaic virus (one time)



Celery mosaic virus
Cucumber mosaic virus



Chervil (Anthriscus cerefolium) None

Coriander (Coriandrum sativum) None

Cumin (Cuminum cyminum) None

Dill (Anethum graveolens) None

Fennel (Foeniculum vulgare) None

Lovage (Levisticum officinale) None

Parsley (Petroselinum crispum) Celery mosaic virus?
Cucumber mosaic virus

Parsnip (Pastinaca sativa) None


Cardamom (Elettaria sp) None

Ginger (Zingiber officinale) None



ALFALFA MOSAIC VIRUS (AMV): This virus is probably present in most if not all alfalfa plantings.
Symptoms are usually not evident. Studies vary as to the amount of damage this virus causes in alfalfa. AMV
infects plants in over 50 plant families. It is primarily transmitted via seed and aphids but it can be spread via
plant sap. Practical controls for this virus are not available.

BARLEY YELLOW DWARF VIRUS (BYDV): Priorto 1990, BYDV occurred occasionally in wheat and
oats in Florida. Epidemics occurred in the panhandle in 1949, 1956, and 1959. Beginning in 1991, BYDV
has occurred in wheat and oats for five consecutive years. In 1994 a severe epidemic occurred. Many grass
species are susceptible to BYDV. Spread of BYDV is by aphids. It has not been transmitted via seed or
mechanically with plant sap. The use of resistant varieties is the best control. Later planting in the fall and
insecticidal sprays aid in reducing this disease.

BEAN COMMON MOSAIC VIRUS (BCMV): This virus has been detected in breeding pedigrees in Florida
but not in commercial plantings, at least in the past 20-25 years or so. BCMV is transmitted primarily by seed
and aphids. Transmission via plant sap can also occur. The host range for BCMV is primarily in legumes and
different studies vary as to the susceptibility of various legume species. Like many viruses, strains of BCMV
exist and varieties differ in regard to susceptibility and symptom expression. The only known occurrences of
BCMV in Florida were in beans and Siratro. An effective seed indexing program by seed producers and
distributors has so far offset potential problems from this virus.

BIDENS MOTTLE VIRUS (BiMoV): This virus is spread primarily by aphids but is sap transmissible.
BiMoV has been found in lettuce, escarole, endive, and lupine in Florida. In addition, hairy beggarticks
(Bidens pilosa) and Virginia pepperweed (Lepidium virginicum) are major source-weeds for BiMoV. Cressleaf
groundsel (Senecio glabellus) has been found to carry BiMoV. BiMoV is widespread in Florida and has been
found in plant species from five plant families. Control of BiMoV is by eliminating hairy beggarticks and
Virginia pepperweed within or near production fields.

BLACKEYE COWPEA MOSAIC VIRUS (BICMV): This virus occurs commonly in Florida when seed
are planted that have not been indexed to be free of B1CMV. Seed produced in Oklahoma, Wyoming, Texas
and other areas in the western USA are more likely to be free of this virus compared to seed produced in the
southeastern USA. This virus has caused total ruination of plantings of Vina spp. in Florida. B1CMV is
transmitted primarily by seed and aphids but it is sap transmissible. Although B1CMV can infect plants in
seven plant families, it is primarily a problem in Florida in southern peas, cowpeas and other Vigna spp. The
only control is to use seed that has been indexed free of B1CMV.

CELERY MOSAIC VIRUS (CeMV): This virus was once called western celery mosaic virus. It is not seed-
borne and is limited to plants in the celery family (Umbelliferae). Mockbishopweed (Ptilimorium capillaceum)
and wild cherry (Apium leptophyllum) are possible sources of CeMV but celery is a more likely source.
Aphids are considered the main vector for CeMV but leafminers have been shown to transmit CeMV. Celery
plantings should be isolated to the extent possible and growers should observe a celery-free planting period each
and every year.


CORKY RINGSPOT (TOBACCO RATTLE VIRUS, TRV): This disease occurs in the northeast potato
growing area in Florida. It is the most important viral disease in potato in Florida. Other viruses occur from
time to time in potato in Florida, but they have not been of significant consequence. In the field, TRV is
transmitted by a dozen species of stubby root nematodes. Little is known about how these nematodes acquire
the virus or how this disease becomes established in fields. Seed pieces have been shown to carry the virus but
transmission of the virus from these seed pieces to nematodes has not been proven. This disease tends to recur
in the same areas of a field from year to year. Spread within or between fields may occur via soil adhering to
equipment but even this aspect of spread has not been proven. Spread within a field from an infested area may
be slow or does not occur. Symptoms occur in the tubers but not the vines. In the field, the best diagnostic
technique is to look for arcs or rings on the surface or within the tuber. For some varieties (Atlantic) the arcs
or rings may be diffuse and not clear-cut. Other symptoms include specks on the tuber surface, tuber
malformation, and tuber cracking. Because this virus has a wide host range, resistant varieties and the use of
certain soil-applied nematicides (primarily Temik) are the primary controls. Multiple sprays of Vydate
(insecticide-nematicide) have been somewhat effective. At this time the varieties Superior and Pungo are the
most resistant. This viral disease has not been a problem in other crops in Florida.

CUCUMBER MOSAIC VIRUS (CMV): Prior to 1970, CMV was identified fairly often, particularly in
south Florida. Since 1970, CMV became a problem of lesser importance until 1995 & 1996 when CMV
became severe in tobacco and peppers (hot) in Alachua County. Interestingly, large patches of Commelina
sp. were present in some fields in Alachua County. CMV had been associated with Commelina spp.
previously. Commelina spp. includes day flower and wandering jew. Celery, cucumber, squash, cantaloupe,
tomatoes, and sometimes pepper had been the crops primarily infected with CMV. Lilies previously grown
in Highlands County are susceptible to CMV. However, CMV has a wide host range including 40 or more
plant families. In Florida, plants within 10 plant families have been identified with CMV. Apparently, infected
propagation stock of gladiolus are brought into Florida commonly but secondary spread to other gladiolus or
other crops in Florida appears to be low. CMV is reported to be worldwide in distribution. Strains of CMV
have been reported to be seed-bore in some species, including cowpea. Within the field, CMV is transmitted
by aphids primarily, but mechanical transmission with plant sap can occur. Symptoms are variable including
mild mosaic to severe plant deformation and stunting. This virus has many strains including the "southern
celery mosaic virus."

DASHEEN MOSAIC VIRUS (DsMV): This virus is recognized as a problem in the production of quality
ornamental foliage plants in the Araceae family (Caladium, Aglaonema, Dieffenbachia, etc). However, malanga
and taro are two aroid plants that are quickly increasing in acreage in southern Florida because of the growing
Hispanic population. Both of these crops are susceptible and have been infected with DsMV in Florida. DsMV
is transmitted primarily by aphids and clonal propagation but not by seed. It is also transmissible by plant sap.
For taro and malanga no controls are available at this time. In the ornamental foliage plant industry, sanitation,
insect control and tissue culture are used to control DsMV.

LETTUCE MOSAIC VIRUS (LMV): This virus caused severe losses to lettuce during the early 1970's.
Since the establishment ofthe mandatory state seed indexing program for freedom from LMV, this viral disease
has become a very sporadic problem in Florida. LMV is spread primarily by infected seed and aphids, but it
can be transmitted mechanically from contaminated sap. Although LMV has been found in plant species from
10 plant families, weed sources have not maintained LMV to the level necessary to initiate epidemics.
Lambsquarters (Chenopodium album) has been found to be naturally infected with LMV in Florida.

dwarf mosaic virus strain A is a distinct virus and infects Johnson grass. Maize dwarf mosaic virus strain B
is a strain of sugarcane mosaic virus and does not infect Johnson grass. Like other strains of sugarcane mosaic


virus, maize dwarf mosaic virus is spread by aphids. It has been found in Alachua, Dade and Levy Counties
in corn. Johnson grass has been naturally infected in Alachua and Levy Counties. Control includes the use of
resistant varieties, if available, and the elimination of Johnson grass in the vicinity of corn plantings.


The official identity of PRSV-W is papaya ringspot virus type W. Although WMV 1 is sap transmissible, it
is spread primarily by aphids from infected cucurbitaceous weeds and crops. However leafminers also can
transmit PRSV-W. This is not a seed borne virus. Control can be achieved by eliminating volunteer cucurbit
crops and cucurbit weeds near the crop. Creeping cucumber and balsam apple are two major host weeds for
PRSV-W. When planting cucurbits, separate them from other plantings of cucurbits to the extent possible.
Keep this point in mind when you are planning for successive plantings. This virus predominates in south and
central Florida but is found in North Florida later in the primary watermelon season and during the summer
and fall.

PEANUT MOTTLE VIRUS (PeMoV): Although this virus can be detected in many peanut plantings in
Florida, with or without symptoms, its effects on yield and quality of the crop is unknown. It has also been
detected in soybeans with and without symptoms. Mosaic symptoms and black specks on Cassia sp. have been
associated with PeMoV in Florida. Beans are another host. PeMoV is transmissible via peanut seed and aphids
primarily but it is also sap transmissible. No control measures are being used.

PEANUT STRIPE VIRUS (PStV): This virus was detected in breeding pedigrees of peanuts in Florida in
1983. It has rarely been detected in commercial plantings up to this point in time in Florida. It is transmitted
via seed and aphids primarily but it is sap transmissable. It was introduced into the United States via peanut
pedigrees that were introduced from Asia for use in breeding programs. The presence of this virus in the United
States exemplifies how easily new, unnecessary problems become established into different geographical areas.
It is conjecturable as to the amount, if any, of damage that was caused by this strain of this PStV. Certainly,
the mere presence ofthis virus in breeding stocks had caused considerable disruption of various peanut research
and Extension programs. Efforts were made to release seed from the Florida Foundation Seed Producers Inc.
that were free of this virus via a seed indexing program. However by the early 1990's, that program waned with
lack of interest by those that thought it was important, initially.

PEPPER MOTTLE VIRUS (PepMoV): In Florida, this virus was first described from Palm Beach County
in the early 1970's. It has also been found in Collier County. It has not been found in North Florida. At one time
it was thought to be a strain of potato virus Y. Along with Potato virus Y and tobacco etch virus, PepMoV
caused significant damage to peppers grown in Palm Beach County. Pepper is the main host but tomato and
Datura meteloides are also susceptible. The latter host is a reservoir for PepMoV in Arizona. Although
PepMoV is sap transmissible, aphids are the main vectors for spread. PepMoV has not been detected in seed.
The primary controls for PepMoV include the use of resistant varieties (e.g. DelRay Bell), the use of disease
free transplants, and spraying with JMS Stylet Oil. In some situations, adjusting the planting date to avoid
primary aphid flights has proven worthwhile but has sometimes interfered with critical market periods.

POTATO VIRUS X (PVX): It is often assumed that most seed piece stocks of potato and their resulting
plants are infected with PVX. In Florida, the extent of contamination of seed pieces and plants is not known.
Symptoms of PVX are not always expressed. Symptoms of PVX are most likely to be expressed during cooler
temperatures or when the plant is also infected with other viruses. PVX plus PVY are reported to cause rugose
mosaic symptoms. Potato virus X is highly contagious via plant sap transmission and is transmitted via seed
pieces. Grasshoppers and one soil fungus have transmitted PVX. Because PVX is easily sap transmitted, many
methods of transmitting this virus can occur during tuber handling stages. Cutting knives are known to be one
mechanical type of transmission. Potato is the principal host for PVX but tobacco and tomato are reported to
be susceptible. Yield losses from this virus have been reported but in Florida such information is not known.


Control is not always deemed necessary for this virus, but regardless, the grower should attempt to purchase
seed stocks that are certified free of most if not all viruses.

POTATO VIRUS Y (PVY): This virus is spread primarily by aphids but mechanical transmission is
possible. Several solanaceous weeds and crops are commonly infected in Florida. Peppers, tobacco and tomato
are the crops most commonly infected in Florida. This is not a seed-bore virus but could be transmitted via
clonal propagation in crops such as potatoes. Roguing weeds such as black nightshade, groundcherry, and
jimsonweed and destroying old crop debris and volunteers in and near fields, greenhouses and plant beds will
reduce sites that perpetuate this virus. Use disease free transplants. Spraying correctly with JMS Stylet Oil will
reduce spread of PVY and certain other aphid transmitted viruses in peppers and tomatoes. Some pepper
varieties have some resistance to certain strains. Adjusting planting dates to avoid major aphid flights has been
somewhat worthwhile in some situations but has interfered with critical market periods.

SOIL-BORNE WHEAT MOSAIC VIRUS (WSBMV): This has been the most important viral disease in
wheat in Florida since it was first found in 1970 in Escambia County. Later it has been found in Okaloosa,
Madison and Santa Rosa Counties. Although this virus can be spread by sap transmission from plant to plant,
the most common mechanism of spread is by movement of soil that contains the fungal vector, Polvmvxa
graminis. Mosaic symptoms appear in leaves from three to four weeks after planting up through April in
Florida. Triticale, rye and barley are susceptible, but only wheat has been infected in commercial situations
in Florida. The best control is the use of resistant varieties. Soil clinging to farm equipment should be removed
prior to moving the equipment from infested to noninfested fields. In Escambia and Santa Rosa Counties, this
viral disease is so widespread, the cleaning technique may no longer be useful for this virus. Later planting
dates with adaptable varieties reduce symptom expression to some extent but yields will still be reduced by this
disease. All factors that contribute to stress of the crop should be reduced to the extent possible when
susceptible varieties are planted.

SOYBEAN MOSAIC VIRUS (SbMV): This virus occurs in soybeans in Florida but it is not a widespread
problem. However, SbMV has caused significant plant and yield losses elsewhere. When plants are infected
with SbMV and certain other viruses (eg peanut mottle), strong symptoms of rugosity, mosaic and stunting
occur; this has been seen on occasion in Florida. SbMV is transmitted primarily by a seed and aphids but it
is sap transmissible. Although many legume species are susceptible to SbMV by artificial inoculations,
soybeans are the only field-grown crop of concern at the present time. No controls are available for SbMV
in Florida.

SQUASH MOSAIC VIRUS (SMV): This virus is uncommon in Florida. The occurrence of SMV in
commercial cucurbits in Florida has been documented only in cantaloupe. It is common for growers to refer
to any mosaic symptoms in squash to be "squash mosaic". Watermelon mosaic virus 2, Papaya ringspot virus
type W, and Zucchini yellow mosaic virus are the most commonly occurring viruses in squash or other
cucurbits in Florida. The distinction of these viruses is important because SMV is seedbome. Also, SMV is
transmitted via certain beetles and grasshoppers whereas watermelon mosaic virus 2, Papaya ringpot virus type
W and Zucchini yellow mosaic virus are transmitted primarily by aphids. SMV infects plants in the cucurbit
(gourd) family. Control for SMV at this time is not warranted in Florida.

SUGARCANE MOSAIC VIRUS (SCMV): SCMV occurs in Florida in sugarcane but has not caused
significant damage. Varieties (clones) are inoculated with various strains of SCMV priorto release to determine
what degree of resistance is available. It is a major part of varietal development so that SCMV does not become
a severe problem in Florida as it has in other states. SCMV is spread primarily by aphids and infected seed
pieces but it is sap transmissible. The host range of this virus is limited to certain grass crops including corn,
St. Augustine grass and sorghum. Like many viruses, SCMV consists of strains, each with their own etiological


manifestations. Maize dwarf mosaic virus strain B (see above) is included among SCMV strains but maize
dwarf mosaic virus strain A is a different virus.

TOBACCO ETCH VIRUS (TEV): Spread is primarily by aphids but mechanical transmission is possible.
Several solanaceous weeds and crops are commonly infected in Florida. Peppers, tobacco, and tomato are the
crops most commonly infected. Black nightshade and groundcherry are weeds that often are infected with TEV.
This is not a seed-bore virus. Roguing weeds such as nightshade and jimsonweed and destroying old crop
debris and volunteers in and near fields, greenhouses, and plant beds will reduce sites that perpetuate this virus.
Use disease free transplants. Spraying correctly with JMS Stylet Oil will reduce spread of TEV and certain
other aphid borne viruses in tomato and pepper. Adjusting planting dates to avoid major aphid flights has been
worthwhile in some situations but has interfered with critical market periods.

TOBACCO MOSAIC VIRUS (TMV): TMV is spread primarily by sap transmission and it is highly
contagious. Because of its highly contagious nature, down-the-row spread occurs often in tobacco. Sources
include infected transplants, nearby crop plants or weeds, particularly solanaceous weeds such as black
nightshade, ground cherry, etc. It is typically not seed-bore but could be transmitted via clonal propagation.
Its host range is extensive in broadleaf (non grass) plants. Control is primarily by sanitation such as roguing
of infected plants, reduction of volunteers and suckers by adequate plow down of previous crops, avoidance
of contact with infected plants, and dipping hands in milk or hydrated phosphate detergent before handling
plants. When purchasing tomato varieties, determine from company sources what varieties have resistance.
Such resistance is to certain strains, not all. TMV is primarily a problem in tobacco in Florida and some
ornamental crops. Also, some scientists who work with peppers in the greenhouse in Florida and elsewhere
have noted that a strain of TMV occurs in pepper stock used in breeding studies. Destruction of plant beds
when transplanting is complete and destruction of stalks and roots after harvest is vital. This virus has a
tendency to buildup over the years on farms if stalk and root destruction after harvests is inadequate.

TOMATO MOSAIC VIRUS (ToMV): Some have considered ToMV to be a strain oftobacco mosaic virus,
but these two viruses are distinct even though they are related. Information about tobacco mosaic virus is
applicable to tomato mosaic virus. ToMV is occasionally a problem in tomatoes.

TOMATO MOTTLE VIRUS (TMoV). This virus was first found in southwest Florida in 1989. It is one
of the many geminiviruses that exist. Pseudocurly top virus, bean golden mosaic virus, and cabbage leaf curl,
listed herein are geminiviruses. Tomato mottle virus, like many of the geminiviruses, is spread by whiteflies.
Tomato mottle virus is closely related to sida golden mosaic virus. Tropical soda apple has been naturally
infected with TMov in Florida. Along with damage from whitefly feeding, TMoV has caused severe damage
to yields and fruit quality in tomatoes, particularly in southern Florida.

TOMATO PSEUDO-CURLY TOP VIRUS (TPCTV): This virus has occurred usually at low levels in
tomatoes for many years, possibly since the mid 1940's. However, the incidence has been as high as 50% in
one field. It is spread by treehoppers. Because the symptoms include highly deformed plants, it raises instant
concern by growers. It is most likely found in South Florida production fields during the fall crop. Roguing is
the main control. Black nightshade has been infected frequently with TPCTV as well as other viruses. Control
of this solanaceous weed is important when producing solanaceous crops such as tomato, tobacco, and pepper.

TOMATO SPOTTED WILT VIRUS (TSWV): This virus was found in Florida in tomatoes and peanuts
in 1986. Some believe that TSWV was present in Florida earlier in gladiolus imported from other states. Since
1986, TSWV has spread from the panhandle of Florida to the southern tip of the peninsula. Also, it has been
found in Florida in tomato, tobacco, pepper, watermelon, impatiens, gloxinia, and other ornamentals.
Suspected occurrences in Florida include african violet, dieffenbachia, coffee senna, and Mexican tea. Spread
of TSWV is primarily by thrips and recently, populations of thrips have increased tremendously in Florida.


Mechanical spread from plant sap is possible. This virus has an enormous host range (34 plant families).
Control of TSWV is not easy. Insecticidal sprays for thrips may offer some control. However, insecticidal
sprays have increased the incidence of TSWV in peanuts. Roguing has been done but the benefits of such are
not known although it seems reasonable that roguing would reduce secondary spread from within the field.
Ornamental greenhouse production sites that contain TSWV are sometimes identified as being sources of
TSWV for field-grown crops. Establishing high density stands of peanuts reduces incidence of TSWV. Some
varieties of peanut have moderate resistance to TSWV.

TOMATO YELLOWS VIRUS (ToYV): This virus was first found in Florida in 1978. It is spread by
aphids and apparently is not mechanically transmissible. ToYV has occurred erratically since 1978. Use of
JMS Stylet Oil sprays has reduced spread of this viral disease. Insecticidal sprays may also offer control of
this aphid-bome virus but not most of the aphid-bome viruses in Florida. Although tomato has been the main
host for this virus, potato, black nightshade, ground cherry (Physalis floridana) and jimsonweed (Datura
stramonium) have been infected with ToYV.

TURNIP MOSAIC VIRUS (TuMV): This virus has not been of much consequence in Florida but does exist
commonly on cruciferous weeds in some parts if the state. TuMV is transmitted primarily by aphids but it is
sap transmissible. It is not known to be seed transmitted. TuMV infects plants in over 20 plant families.
Controls for TuMV are not available.


WATERMELON MOSAIC VIRUS 2 (WMV 2): This has become the most widespread virus in squash
and watermelons in central and north Florida. Although WMV 2 is sap transmissible, it is spread primarily by
aphids. Leaf miners have been shown to transmit this virus. WMV 2 has a wide host range including legumes
but the sources) plants for this virus in the field have not been determined. WMV 2 has not been demonstrated
to be seed borne. Recently, varieties of squash with resistance to WMV2 have become available. Fall
plantings or late spring plantings are more likely to incur more damage than early spring plantings. However,
entire early spring plantings have incurred serious damage from WMV 2.

ZUCCHINI YELLOW MOSAIC VIRUS (ZYMV): This virus was found in Florida in 1981. By 1983
ZYMV became severe in some cucurbit fields from Dade to Hamilton Counties, but since then, the incidence
of ZYMV has been sporadic. Although ZYMV can produce symptoms similar to WMV 1 or WMV 2, it has
a tendency to produce severe leaf and fruit distortions. ZYMV is spread primarily by aphids but it is
mechanically transmitted by plant sap. Conflicting reports exist about the seed transmissibility of ZYMV in
squash. Recently, varieties of squash with resistance to ZYMV have become available.