Fancy plants may be carriers of virus pathogens Dr Abe V Rotor
"Viral infected plants cannot be cured. It is through prevention that can stop the disease from being introduced or from spreading." - avr
Moses-in-a-boat (Rhoeo discolor) exhibits dimorphic coloration: healthy plants are green and robust, while the infected ones are pink and stunted pink (center). Such suspicious characteristic should be referred to specialists to prevent further spread of the disease. Humans are the most common agents of transmission of viral and other diseases.
Yellowish and stunted, the plant continues to grow, reproduce and complete its life cycle while carrying a virus that causes the bunchy top appearance of the plant - rosette arrangement of the leaves. Local folks unaware of the condition of the plant just regard it as fancy, which then favors its spread in the banana plantation.
Red pepper (Capsicum annuum), healthy (left) and infected with mosaic virus (early stage) may appear the same, but plant pathologists can easily detect the difference. The virus does not kill the plant, it exaggerates the mosaic and chlorotic patterns as fancy characteristics. This exacerbates the spread of the disease starting with touch to insect bite to plant-to-plant contact in the field.
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"Frog eye" spots and chlorotic venation, including stunting and early defoliation are attributed to a complex of pathogens, with the virus as among the primary causes. Host is Terminalia catappa (PHOTO)
1. Viruses in general cannot be seen with the naked eye. Not even the laboratory light microscope. With the electron microscope we can see and study them.
2. The largest group are mosaic viruses. They cause yellow and green spotting of leaves, stems blossoms and fruits.
5. Plant viruses enter the cells directly through wounds caused by weather, humans, and vectors like aphids, whiteflies, and leafhoppers, mealy bugs, and other organisms which pierce the plant and suck its sap. Horticultural practices like grafting and inarching directly transfer the virus to the new plant.
13. Viruses differ from fungi and bacteria in that they do not produce spores or other structures capable of penetrating plant parts. Viruses enter through wounds, and spread through farming practices.
14. Tobacco virus survives manufacturing process - drying, redrying and making cigars and cigarettes. It remains dormant up to 20 years . Then it resurrects on a healthy tobacco plant or any member of the Solanaceae family – by the mere touch of a smoker – and the virus in no time spreads like fire infecting field after field.
15. On entering a host the virus begins to multiply by inducing host cells to produce more of its kind. Viruses do not cause disease by consuming or killing cells but by taking over the metabolic cell processes, resulting in abnormal cell functioning.
Beware! These plants samples show the characteristic plant virus symptoms and signs. They are highly infectious to healthy plants of their species and most likely to others plants belonging to the same family. Rogue them out of the field or garden, burn them to eliminate source of inoculation. 
Tobacco infected with the classical Marmor tabaci virus, which can survive flue-curing, redrying and cigar- and cigarette manufacture, remaining dormant for as long as twenty years, then resurrect in living host plants, which belong to Family Solanaceae to which Irish potato, tomato, eggplant and pepper belong. ~
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"Frog eye" spots and chlorotic venation, including stunting and early defoliation are attributed to a complex of pathogens, with the virus as among the primary causes. Host is Terminalia catappa (PHOTO)
Facts about plant viral diseases.
1. Viruses in general cannot be seen with the naked eye. Not even the laboratory light microscope. With the electron microscope we can see and study them.
2. The largest group are mosaic viruses. They cause yellow and green spotting of leaves, stems blossoms and fruits.
3. Mosaic destroys chlorophyll, resulting to stunted growth, and therefore poor harvest, and may lead to the death of the plants usually in the later stage.
4. Another group of viruses is called yellows, that causes yellowing, leaf curling and dwarfing. Mode of attack is to block the plant's vascular system, preventing water and nutrients to pass through. Infected plants show no symptoms, and therefore transmit the disease without detection.
5. Plant viruses enter the cells directly through wounds caused by weather, humans, and vectors like aphids, whiteflies, and leafhoppers, mealy bugs, and other organisms which pierce the plant and suck its sap. Horticultural practices like grafting and inarching directly transfer the virus to the new plant.
6. Viral infected plants cannot be cured. It is through prevention that can stop the disease from being introduced or from spreading.
7. Foremost is quarantine. Second is to plant only virus free seeds, because viral disease is systemic, that is, all parts of the plant carries the virus.
8. Rouging infected plants and burning them is a common method on the farm. Eliminate volunteer crops as these may serve a continuing or alternate host of the virus.
9. Crop rotation and fallowing (allowing the farm to rest) breaks the life cycle of the disease.
10. Tobacco mosaic caused by a virus, Marmor tabaci, is cosmopolitan. It is known to infect more than 150 types of plants which include vegetables, flowering plants and weeds.
11. The most important plants infected belong to Family Solanaceae which is composed of commercial crops valued at billions of dollars in world agriculture and trade - tomato, tobacco, eggplant, pepper, Irish potato.
12. Virus-infected plants are mistaken for overdose in pesticide spray, side effect of herbicides, pollution in various forms, but the most confusing likeness is deficiency in minerals like iron, zinc, and boron, although these are needed by plants in trace quantities. Ferrous deficiency causing chlorosis and stunting, often thought to be incipient viral signs.
13. Viruses differ from fungi and bacteria in that they do not produce spores or other structures capable of penetrating plant parts. Viruses enter through wounds, and spread through farming practices.
14. Tobacco virus survives manufacturing process - drying, redrying and making cigars and cigarettes. It remains dormant up to 20 years . Then it resurrects on a healthy tobacco plant or any member of the Solanaceae family – by the mere touch of a smoker – and the virus in no time spreads like fire infecting field after field.
15. On entering a host the virus begins to multiply by inducing host cells to produce more of its kind. Viruses do not cause disease by consuming or killing cells but by taking over the metabolic cell processes, resulting in abnormal cell functioning.
Beware! These plants samples show the characteristic plant virus symptoms and signs. They are highly infectious to healthy plants of their species and most likely to others plants belonging to the same family. Rogue them out of the field or garden, burn them to eliminate source of inoculation. Diseased cassava (Manihot utilissima)
Cucumber (Cucumis sativus). Virus infective to members of
Family Cucurbitae, like squash, ampalaya and melon
Lettuce (Lactuca sativa), mosaic virus likely infectious to other cucurbits
Squash (Cucurbita maxima) infective with the same mosaic virus of cucurbits.
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Rice Tungro Disease - Scourge of Rice
Rice tungro is caused by the combination of two viruses, which are transmitted by leafhoppers. It causes leaf discoloration, stunted growth, reduced tiller numbers and sterile or partly filled grains. Tungro infects cultivated rice, some wild rice relatives and other grassy weeds commonly found in rice paddies.
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