Plant Disease Type:
Virus |
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| This disease
attacks: |
It is known to infect members of nine plant families, and at least 125 individual species, including tobacco, tomato, pepper, cucumbers, and a number of ornamental flowers. There are many different strains.
The Tobacco Mosaic Virus has been known to cause a production loss for flue cured tobacco of up to two percent in North Carolina.
In Minnesota, common plant hosts for the mosaic virus are tomato, pepper, petunia, snapdragon, delphinium, and marigold. Tobacco mosaic virus also has been reported to a lesser extent in muskmelon, cucumber, squash, spinach, celosia, impatiens, ground cherry, phlox, zinnia, certain types of ivy, plantain, night shade, and jimson weed. Although tobacco mosaic virus may infect many other types of plants, it generally is restricted to plants that are grown in seedbeds and transplanted or plants that are handled frequently. |
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| General Information
about
Tobacco Mosaic Virus : |
When Tobacco Mosaic Virus infects a tobacco plant, the virus enters mechanically (For example through a ruptured plant cell wall) and replicates. After its multiplication, it enters the neighboring cells through plasmodesmata. For its smooth entry, Tobacco Mosaic Virus produces a 30,000 dalton protein called P30 which tends to enlarge the plasmodesmata. TMV most likely moves from cell-to-cell as a complex of the RNA, P30, and replicase proteins.
The first symptom of this virus disease is a light green coloration between the veins of young leaves. This is followed quickly by the development of a “mosaic” or mottled pattern of light and dark green areas in the leaves. These symptoms develop quickly and are more pronounced on younger leaves. Mosaic does not result in plant death, but if infection occurs early in the season, plants are stunted. Lower leaves are subjected to “mosaic burn” especially during periods of hot and dry weather. In these cases, large dead areas develop in the leaves.
This constitutes one of the most destructive phases of tobacco mosaic virus infection. Infected leaves may be crinkled, puckered, or enlongated.
Consumption of tobacco products infected with the Tobacco Mosaic Virus has been found to have no effect on humans.[citation needed]
| This plant disease
can commonly be found in these places: |
The plant disease caused by tobacco mosaic virus is found worldwide. The virus is known to infect more than 150 types of herbaceous, dicotyledonous plants including many vegetables, flowers, and weeds. Infection by tobacco mosaic virus causes serious losses on several crops including tomatoes, peppers, and many ornamentals. Tobacco mosaic virus is one of the most common causes of virus diseases of plants in Minnesota.
North America, Europe, Asia, Africa
| How to get rid
of or kill this disease: |
Unlike fungicidal chemicals used to control fungal diseases, to date there are no efficient chemical treatments that protect plant parts from virus infection. Additionally, there are no known chemical treatments used under field conditions that eliminate viral infections from plant tissues once they do occur. Practically speaking, plants infected by viruses remain so. Thus, control of tobacco mosaic virus is primarily focused on reducing and eliminating sources of the virus and limiting the spread by insects. Tobacco mosaic virus is the most persistent plant virus known. It has been known to survive up to 50 years in dried plant parts. Therefore, sanitation is the single most important practice in controlling tobacco mosaic virus.
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Control for Seedling Growers and Gardeners
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The most common method of transferring the virus from plant to plant is on contaminated hands and tools. Workers who transplant seedlings should refrain from smoking during transplanting and wash their hands frequently and thoroughly with soap and water. Tools used in transplanting can be placed in boiling water for 5 minutes and then washed with a strong soap or detergent solution. Dipping tools in household bleach is not effective for virus decontamination. Any seedlings that appear to have mosaic symptoms or are stunted and distorted should be removed and destroyed. After removing diseased plants, never handle healthy plants without washing hands and decontaminating tools used to remove diseased plants.
Persons purchasing small tomato plants for transplanting should beware of any plants showing mottling, dwarfing, or stunting. Avoid the purchase of any affected plant. Gardeners are advised to follow the same procedures recommended for greenhouse workers when handling tomato transplants. Other control methods for home gardeners include roguing (removal of diseased plants), destruction of diseased and infected plants, and control of weeds and chewing insects. When roguing and destroying mature diseased plants from the home garden, be sure to wash hands and decontaminate any tools used in the process before contacting healthy plants.
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Control for Commercial Producers
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Commercial greenhouse producers of tomatoes should follow control practices for seedling production as stated above. It is essential for commercial growers to constantly inspect and rogue diseased production plants while the plants are in the seedling stage. An experienced individual, who is familiar with the tobacco mosaic virus symptoms, should do the initial inspection.
Roguing of young production plants is recommended and should take place before workers are allowed to prune or tie up production plants. When removing diseased plants, also remove one plant on either side of the diseased one. The reason for this is that it is almost impossible to remove a diseased plant and not contaminate the healthy adjacent plants. Never attempt to transplant a healthy tomato into the soil from which a diseased plant was removed. Roots from diseased plants will remain in the soil and provide the virus inoculum for the new transplant.
As a matter of routine, soils from which production plants have been removed, following harvest, should be steam sterilized before the introduction of new seedlings. Steam sterilization can be accomplished by steam or air-steam mixtures. In the preparation of soil for steam sterilization, sift it to remove clumps and large pieces of organic matter. The total soil mixture will have to be heated to a temperature of 200° F for 40 minutes. Since high temperatures are required, steam sterilization must be done in an enclosed system. Temperatures within the steam sterilization system should be monitored by high temperature thermometers to make sure the desired temperature has been reached. Steam sterilization of soil also will eliminate fungi, insects, nematodes, and weeds from the soil. Steam sterilization also is recommended for gravel mixtures used in hydroponic operations following the same procedure described above.
Grow individual production plants in separate containers so that the soil or growing media can be removed when roguing infected production plants. Remember that the soil harbors old root tissues that may serve as inoculum when new roots are introduced. Growing production plants in separate containers is also useful for the control of root diseases caused by fungi and bacteria.
TMV can be treated almost as an organic chemical, rather than an infective agent.
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