By Dr. Thomas T. Yamashita
The tobacco mosaic virus (TMV) is one of many viruses of the genus tobamovirus, which infect a vast number of plants, including varieties of tobacco, tomato, potato, and squash. The effects of the tobacco mosaic virus were recognized in the 1880s, but their cause was not identified until the 1930s. In 1898, Dutch microbiologist Martinus Beijerinck invoked the long-abandoned term ‘virus’ in his studies of TMV in order to differentiate it from bacterial diseases. TMV was the first identified virus, and played a critical role in our modern day understanding of viral diseases.
While TMV’s place in the history of science is fascinating, the disease has been a scourge on generations of growers. Studies have shown that TMV infection reduces tomato yields by a third, costing growers billions of dollars. But why is this disease so prevalent, readily spread, and damaging?
Tobacco mosaic virus can reside in hundreds of hosts, and can be transmitted by insects as well as human intervention.
TMV can be transmitted by chewing insects, such as leafhoppers. However, the primary vector of TMV is man, via direct handling or use of contaminating farming equipment. The virus can survive for long periods of time in dropped stalks and leaves in the soil, as well as on the surface of contaminated seeds. Thus, farm workers can readily disseminate TMV by handling infected plants prior to touching uninfected plants.
The ease of spreading TMV is magnified by the fact that more than 200 species of plants belonging to 30 families can serve as reservoir hosts for the virus. Particularly common reservoirs include pepper, potato, eggplant, gooseberry, apple, grapevine, and more. The presence of TMV in populations of these reservoir species is practically ubiquitous in some areas, making the virus impossible to exterminate.
Worse yet, the virus is incredibly durable. Tests have shown that the virus particle can withstand temperatures over 195 degrees Fahrenheit, as well as more than 4 years in undecomposed plant matter.
When tomato plants are infected with TMV, the first symptom to appear is the appearance of the trademark mosaic pattern on affected leaves, caused by the reduction or loss of chlorophyll (chlorosis). As conditions worsen, leaf growth is stunted, with compression of leaf tissues, as well irregular serrations along the margins of leaves. As plant health worsens, leaf curling appears, as well as tell-tale fern-like leaf formations. This eventually results in full-scale stunting of plant growth, and significantly reduced yields.
Controlling the spread of TMV requires careful handling of infected plants, and proper disposal of tissues and plant debris.
Growers need to ensure that workers avoid handling infected plants where possible. When it’s necessary to do so, hands should be washed thoroughly with soap and water prior to handling other plants. Further reductions in transmission can be obtained with microbially induced rapid decomposition of infected plant matter.
But what about already infected plants? Fusion 360 has found that diseased tomato plants can be restored to proper health with judicious adjustments in nutrition. With appropriation nutritional supplementation, plants can achieve a non-expressive, quiescent state in which the spread and reproduction of TMV is suppressed, resulting in normal, healthy growth.
To learn more about how to treat and eliminate the transmission of tobacco mosaic virus, contact Fusion 360 by calling (888) 634-3360, or by sending us a message using our contact form.
