VIRUS: Modes of Transmission

By insects, mostly aphids and leaf- hoppers, grasshoppers and beetles; seed and pollen are less common transmitters; meristerns almost always carry virus if the parent was infected; mechani cal transmission is the greatest danger . OA84-115

More than 380 species of animals can transmit at least one virus; 76% of the known insect virus vectors are aphids, scales and mealybugs, but mostly aphids; Aphis gossypi is a vector of 81 plant viruses ; controlling them will likely check the spread of virus. A87-1015; 1052; new one from Holland. OA80-44

Virus	Comments
VIRUS: Basics and Prospects for the Future Plants, unlike animals lack a protective antibody system but virus is rarely if ever seed-transmitted, even when both parents are infected; it is unfortunate that virus do not kill their hosts; the Linnaean hierarchical system of names does not apply to them so they have common names like "Cymbidium mosaic virus"; no antiviral compound has been found (to May 1984); tissue culture has spread a lot of virus, but they are not invincible and the prognosis for control is excellent. A82-719; A84-505; OBIV-268	0
VIRUS: Bean Yellow Mosaic Virus Allied to the Potyvirus group that have insect vectors, mostly aphids; Japanese in origin, recently reported in the U.S. OIE86Jan-9; may be spreading and could cause widespread problems. AH86-3;9	0
VIRUS: Cattleya labiata Var. Alfrediana A famous variety originally hailed for its extraordinary coloring about 1890, recognized as a virus infection in 1949, possibly a first for orchids. A83-1162	0
VIRUS: Cigarette Transmittal Tobacco Mosaic Virus is highly prevalent in tobacco and is a problem for smokers working with susceptible plants; orchids when inoculated with TMV develop only a local necrotic infection which does not move systematically through the plant; however, smokers should exercise usual cautions because of the wide host range of TMV. A84-17	0
VIRUS: Control by Chemicals The use of household bleach is recommended in concentrations varying from 20% upward to full strength, timed from 30 seconds to 10 minutes; refer to A82-725	0
VIRUS: Control by Flame or Heat A resume of procedures recommended; to A82-726	0
VIRUS: Control of Hand Transmission Use cheap plastic gloves; or wash the hands thoroughly with soap and water after each handling of a plant or materials. A83-600	0
VIRUS: Controls 1.discard infected plants, 2. sterilize cutting instruments, 3. sterilize pots, 4. keep moisture from dropping on pots below and do not let roots from plants intertwine, 5.sterilize benches before re-using. OIE86Jan-8; more on this, A82-264A review of conditions in California, with areas of research; rarely is Cymbidium mosaic found in a cymbidium anditt is really the common virus in cattleyas and some of them are doubly infected; prevention is imperative; flaming of cutting tools must be at high heat, bleach must be at 202 solution; use plastic potting sticks, not wood, for better sterilizing. OA83-72; Florida update, F86-9; a New Zealand update, N287-178	0
VIRUS: Cymbidium Mosaic Virus (cymv) and Tomato Mosaic Virus-0 (tmv) These two are the most important economically in the business. AH86-2; 4	0
VIRUS: Destroy? Quarentine? Cure? The extra time and care required to keep a diseased plant are considerable; cure is impossible; Virazole has suppressed or inhibited the synthesis of some viruses; refer to AH86-35	0
VIRUS: Detection and Diagnosis The technical process with a light microscope; refer to A86-996; principle and applications used; indicator plants and electron microscopy; light microscopy serology; necessary equipment; incidence in collections and genera.; refer to Wll-402; 407	0
VIRUS: Diseases of Orchids History, recent developments; different types; refer to OA83-136; use of electron microscopy in detection, AH86-31	0
VIRUS: Eradication From a Collection Efforts to rid CMV and ORV from a personal collection over a period of four years described; tests showed plants grown from 15 to 25 years were 100% infected, those grown one to two years only 16% infected, all of which were discarded ; procedures to rebuild a virus-free collection outlined. A83-261	0
VIRUS (GENERAL): Diseases of Orchids A scientific review; refer to Wl-431-f; OR77-195+; OB1-186+Those which infect orchids are few in numbers and largely restricted to the Orchidaceae: they are Cymbidium Mosaic Virus, Cattleya Mosaic Virus, Odontoglossum ringspot virus and Cattleya blossom brown necrotic streak disease (in Australia). OD68-149	0
VIRUS (GENERAL): Seedlings Not Likely Free of Virus Pollinia from virused plants contain apparently high concentration of virus; the only way seedlings could be free of virus is for the virus to be extruded or inactivated by formation of gametes (pollen and eggs) by haploid division of germinal cells. Does this happen? A71-622	0
VIRUS (GENERAL): Where Does Virus Come From? Two random surveys have failed to uncover any virus-infected plants in the wild; Africa, Central America, South America and Southeast Asia. F79-173	0
VIRUS: Groups and Methods of Transmission As defined by the Intenational Committee for the Taxonomy of Virus, and showing those that infect: orchids and their insects of transmission; list of names of orchid viruses. A84-507	0
VIRUS: How to Detect It A diagnostic technique developed to detect Cymbidium Mosaic and Odontoglossum Ringspot, the double radial diffusion test with antibodies produced by immunizing animals, usually rabbits;refer to A83-255	0
VIRUS: Incidence Table showing frequency of infection of about 2 0 genera by CMV and ORS and related to length of time in cultiva- tion; refer to W10-281	0
VIRUS: In Cymbidium Alexanderi 'westonbirt' The original seedling was sown on a cattleya host plant's pot and was likely the source of the virus, which was distinctive from the beginning, but was never free of the "ticking" that became a sign of CMV; so-callled "virus-free" plants never produced notable off-spring. OA80-178	0
VIRUS: Indicator Plants Five plants listed with details ; refer to AH86-15; seed for Gomphrena globosa and Cassia occidentalis can be purchased from suppliers; address given. A86-251; six plants listed, with details of use; refer to AH86-19	0
VIRUS: In Native and Cultivated Plants Table showing incidence of CMV and ORV in 17 main genera and 5 3 miscellaneous genera; none out of 438 native genera was infected; 362 out of 1312 culti- vated genera were infected. A83-255	0
VIRUS: Interferon Seen as Inhibitor Minute amounts sprayed on a plant can stop a virus infection in an hour, is harmle s s to plants and humans; scientists are experimenting. CA84(3)-19; AU84,Sept.	0
VIRUS: In the Wild Cypripedium acaule -- in the woods in Manitoba was found to have symptoms which were identified as virus by Plant Science personnel. CA84(2)-19	0
VIRUS-LIKE SYMPTOMS: Causes Nutritional or chemical disorders, other insect damage produce them; there is an apparent color-break in vandaa: caused by thrips; distorted cymbidium blooms are attributed to feeding of aphids on immature buds; smog, fungi, bacteria, improperly used insecticides also mentioned. OIE86-Sept-16,- qu. from Kado, Virus diseases of orchids (1970)	0
VIRUS: Maintaining a Clean Collection Procedures recommended: No drip to pass from one plant to another, Use no pot a second time, Flame sterilize wire pot-hangers, Re-use no drainage materials, or stakes, or potting materials, Divide plants by pulling them apart or by new razor blades, Wash hands with soap between pottings, Keep snails, roaches, insects, down, Isolate and test poor plants, uarentine and test all new ones. A87-1055	0
VIRUS: Non-viral Symptoms Chlorosis, spots, dots, tip and marginal burns, scorching, water-soaked areas, green and yellow flecking, injuries due to insect feeding, pesticide spray damage; accurate diagnosis is necessary. AH86-11	0
VIRUS: Number Affecting Orchids At least 18 viruses cause various, often destructive diseases known as ringspot, mosaic, mottle, streak, necrosis, etc. AH86-2	0
VIRUS: Persistence When plant parts decay virus is disseminated into the environment; destroy the plant. OA84-112	0
VIRUS: Pollen Transmitted or Not There's no proof that infected plants can be used to produce seedlings free of CMV or ORS. A83-816	0
VIRUS: Problems with Stud Plants Disease is transmitted to the seed through the pollen except in the case of Phalaenopsis, if the seed is removed carefully from the virused pod; virused plants always pose a threat to the virus-free. A82-588; questions and misconceptions dealt with inlO questions with detailed answers, refer to A86-472	0
VIRUS: Removal From Hands Use 3% solution of Tri-Sodium Phosphate and wash first in it then in soap and water; it's difficult to remove. AU87(2)-16	0
VIRUS: Research and Accomplishments A review; serology and prevention methods, etc.; refer to A82-1064; 1180; 1279	0
VIRUS: Riboviren, a New Viruscide A complex drug, very expensive to make, has freed cymbidiums from TMV in the lab. OA83-74	0
VIRUS: Sanitation Heat is the safest method and the most effective, place all tools in an oven at 300 dF for one hour; propane torches are good if blades are first dipped in alcohol before flaming; liquid inactivating solutions .reviewed, refer to AH88-13	0
VIRUS: Spread by Tissue Culture 1. make sure a plant is free before meristemming, 2. keep a clean plant separate in an insect-free greenhouse, for tissue culturing, 3. test the free plants regularly, 4. producing of clean protocorms from a diseased plant takes years. 5. insist on a guarantee that plants are free before buying. SA84-70	0
VIRUS: Testing for By chloroplast agglutination, agar double dif fusion, ELISA, etc.; refer to AH86-25; others, OA83-168	0
VIRUS: Tests by Amateurs They can do an adequate job using either the serological or bioassay techniques, but each test is for only one virus out of many. A86-274	0
VIRUS: Tobacco Mosaic Virus Also called odontoglossum ringspot, is ineffective when sap is diluted 100,000 times, or when heated to 90 dC (194 dF) for ten minutes. OIE87 Jy-4, qu. Kado, Virus diseases of orchids (1970); TMV is very stable and persists in plant debris for years, so burn plants do not compost them. AH86-13	0
VIRUS: Transmission Mechanical, insect and pollen agency, their numbers are uncounted; refer to AH86-11; transmission by pollen does not occur in cymbidiums but has been noted in dendrobiums and phalaenopsis. AH86-12	0

Virus

Comments

VIRUS: Basics and Prospects for the Future Plants, unlike animals lack a protective antibody system but virus is rarely if ever seed-transmitted, even when both parents are infected; it is unfortunate that virus do not kill their hosts; the Linnaean hierarchical system of names does not apply to them so they have common names like "Cymbidium mosaic virus"; no antiviral compound has been found (to May 1984); tissue culture has spread a lot of virus, but they are not invincible and the prognosis for control is excellent. A82-719; A84-505; OBIV-268

VIRUS: Bean Yellow Mosaic Virus Allied to the Potyvirus group that have insect vectors, mostly aphids; Japanese in origin, recently reported in the U.S. OIE86Jan-9; may be spreading and could cause widespread problems. AH86-3;9

VIRUS: Cattleya labiata Var. Alfrediana A famous variety originally hailed for its extraordinary coloring about 1890, recognized as a virus infection in 1949, possibly a first for orchids. A83-1162

VIRUS: Cigarette Transmittal Tobacco Mosaic Virus is highly prevalent in tobacco and is a problem for smokers working with susceptible plants; orchids when inoculated with TMV develop only a local necrotic infection which does not move systematically through the plant; however, smokers should exercise usual cautions because of the wide host range of TMV. A84-17

VIRUS: Control by Chemicals The use of household bleach is recommended in concentrations varying from 20% upward to full strength, timed from 30 seconds to 10 minutes; refer to A82-725

VIRUS: Control by Flame or Heat A resume of procedures recommended; to A82-726

VIRUS: Control of Hand Transmission Use cheap plastic gloves; or wash the hands thoroughly with soap and water after each handling of a plant or materials. A83-600

VIRUS: Controls 1.discard infected plants, 2. sterilize cutting instruments, 3. sterilize pots, 4. keep moisture from dropping on pots below and do not let roots from plants intertwine, 5.sterilize benches before re-using. OIE86Jan-8; more on this, A82-264A review of conditions in California, with areas of research; rarely is Cymbidium mosaic found in a cymbidium anditt is really the common virus in cattleyas and some of them are doubly infected; prevention is imperative; flaming of cutting tools must be at high heat, bleach must be at 202 solution; use plastic potting sticks, not wood, for better sterilizing. OA83-72; Florida update, F86-9; a New Zealand update, N287-178

VIRUS: Cymbidium Mosaic Virus (cymv) and Tomato Mosaic Virus-0 (tmv) These two are the most important economically in the business. AH86-2; 4

VIRUS: Destroy? Quarentine? Cure? The extra time and care required to keep a diseased plant are considerable; cure is impossible; Virazole has suppressed or inhibited the synthesis of some viruses; refer to AH86-35

VIRUS: Detection and Diagnosis The technical process with a light microscope; refer to A86-996; principle and applications used; indicator plants and electron microscopy; light microscopy serology; necessary equipment; incidence in collections and genera.; refer to Wll-402; 407

VIRUS: Diseases of Orchids History, recent developments; different types; refer to OA83-136; use of electron microscopy in detection, AH86-31

VIRUS: Eradication From a Collection Efforts to rid CMV and ORV from a personal collection over a period of four years described; tests showed plants grown from 15 to 25 years were 100% infected, those grown one to two years only 16% infected, all of which were discarded ; procedures to rebuild a virus-free collection outlined. A83-261

VIRUS (GENERAL): Diseases of Orchids A scientific review; refer to Wl-431-f; OR77-195+; OB1-186+Those which infect orchids are few in numbers and largely restricted to the Orchidaceae: they are Cymbidium Mosaic Virus, Cattleya Mosaic Virus, Odontoglossum ringspot virus and Cattleya blossom brown necrotic streak disease (in Australia). OD68-149

VIRUS (GENERAL): Seedlings Not Likely Free of Virus Pollinia from virused plants contain apparently high concentration of virus; the only way seedlings could be free of virus is for the virus to be extruded or inactivated by formation of gametes (pollen and eggs) by haploid division of germinal cells. Does this happen? A71-622

VIRUS (GENERAL): Where Does Virus Come From? Two random surveys have failed to uncover any virus-infected plants in the wild; Africa, Central America, South America and Southeast Asia. F79-173

VIRUS: Groups and Methods of Transmission As defined by the Intenational Committee for the Taxonomy of Virus, and showing those that infect: orchids and their insects of transmission; list of names of orchid viruses. A84-507

VIRUS: How to Detect It A diagnostic technique developed to detect Cymbidium Mosaic and Odontoglossum Ringspot, the double radial diffusion test with antibodies produced by immunizing animals, usually rabbits;refer to A83-255

VIRUS: Incidence Table showing frequency of infection of about 2 0 genera by CMV and ORS and related to length of time in cultiva- tion; refer to W10-281

VIRUS: In Cymbidium Alexanderi 'westonbirt' The original seedling was sown on a cattleya host plant's pot and was likely the source of the virus, which was distinctive from the beginning, but was never free of the "ticking" that became a sign of CMV; so-callled "virus-free" plants never produced notable off-spring. OA80-178

VIRUS: Indicator Plants Five plants listed with details ; refer to AH86-15; seed for Gomphrena globosa and Cassia occidentalis can be purchased from suppliers; address given. A86-251; six plants listed, with details of use; refer to AH86-19

VIRUS: In Native and Cultivated Plants Table showing incidence of CMV and ORV in 17 main genera and 5 3 miscellaneous genera; none out of 438 native genera was infected; 362 out of 1312 culti- vated genera were infected. A83-255

VIRUS: Interferon Seen as Inhibitor Minute amounts sprayed on a plant can stop a virus infection in an hour, is harmle s s to plants and humans; scientists are experimenting. CA84(3)-19; AU84,Sept.

VIRUS: In the Wild Cypripedium acaule -- in the woods in Manitoba was found to have symptoms which were identified as virus by Plant Science personnel. CA84(2)-19

VIRUS-LIKE SYMPTOMS: Causes Nutritional or chemical disorders, other insect damage produce them; there is an apparent color-break in vandaa: caused by thrips; distorted cymbidium blooms are attributed to feeding of aphids on immature buds; smog, fungi, bacteria, improperly used insecticides also mentioned. OIE86-Sept-16,- qu. from Kado, Virus diseases of orchids (1970)

VIRUS: Maintaining a Clean Collection Procedures recommended: No drip to pass from one plant to another, Use no pot a second time, Flame sterilize wire pot-hangers, Re-use no drainage materials, or stakes, or potting materials, Divide plants by pulling them apart or by new razor blades, Wash hands with soap between pottings, Keep snails, roaches, insects, down, Isolate and test poor plants, uarentine and test all new ones. A87-1055

VIRUS: Non-viral Symptoms Chlorosis, spots, dots, tip and marginal burns, scorching, water-soaked areas, green and yellow flecking, injuries due to insect feeding, pesticide spray damage; accurate diagnosis is necessary. AH86-11

VIRUS: Number Affecting Orchids At least 18 viruses cause various, often destructive diseases known as ringspot, mosaic, mottle, streak, necrosis, etc. AH86-2

VIRUS: Persistence When plant parts decay virus is disseminated into the environment; destroy the plant. OA84-112

VIRUS: Pollen Transmitted or Not There's no proof that infected plants can be used to produce seedlings free of CMV or ORS. A83-816

VIRUS: Problems with Stud Plants Disease is transmitted to the seed through the pollen except in the case of Phalaenopsis, if the seed is removed carefully from the virused pod; virused plants always pose a threat to the virus-free. A82-588; questions and misconceptions dealt with inlO questions with detailed answers, refer to A86-472

VIRUS: Removal From Hands Use 3% solution of Tri-Sodium Phosphate and wash first in it then in soap and water; it's difficult to remove. AU87(2)-16

VIRUS: Research and Accomplishments A review; serology and prevention methods, etc.; refer to A82-1064; 1180; 1279

VIRUS: Riboviren, a New Viruscide A complex drug, very expensive to make, has freed cymbidiums from TMV in the lab. OA83-74

VIRUS: Sanitation Heat is the safest method and the most effective, place all tools in an oven at 300 dF for one hour; propane torches are good if blades are first dipped in alcohol before flaming; liquid inactivating solutions .reviewed, refer to AH88-13

VIRUS: Spread by Tissue Culture 1. make sure a plant is free before meristemming, 2. keep a clean plant separate in an insect-free greenhouse, for tissue culturing, 3. test the free plants regularly, 4. producing of clean protocorms from a diseased plant takes years. 5. insist on a guarantee that plants are free before buying. SA84-70

VIRUS: Testing for By chloroplast agglutination, agar double dif fusion, ELISA, etc.; refer to AH86-25; others, OA83-168

VIRUS: Tests by Amateurs They can do an adequate job using either the serological or bioassay techniques, but each test is for only one virus out of many. A86-274

VIRUS: Tobacco Mosaic Virus Also called odontoglossum ringspot, is ineffective when sap is diluted 100,000 times, or when heated to 90 dC (194 dF) for ten minutes. OIE87 Jy-4, qu. Kado, Virus diseases of orchids (1970); TMV is very stable and persists in plant debris for years, so burn plants do not compost them. AH86-13

VIRUS: Transmission Mechanical, insect and pollen agency, their numbers are uncounted; refer to AH86-11; transmission by pollen does not occur in cymbidiums but has been noted in dendrobiums and phalaenopsis. AH86-12

VIRUS: Modes of Transmission

by Robert M. [Bert] Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

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