Protect Your Tomatoes from the Mosaic Virus
"Safeguarding Your Tomatoes: Protecting Against the Mosaic Virus"
Tomato Mosaic Virus What You Need to Know:
Tomato mosaic virus (ToMV) infects numerous vegetable crops worldwide, severely impacting tomato cultivation and production. It overwinters on perennial weeds before being spread via aphids, leafhoppers, and whiteflies - and being carried in seed, cuttings, grafts, or containers that have already been infected.
There's a gene (a piece of DNA that carries information about a particular trait) called Tm-1. This gene is special because it makes tomato plants resistant to the Tomato Mosaic Virus (ToMV). The Tm-1 gene creates a special protein that, even though it doesn't seem to function like other known proteins, can directly latch onto and interfere with the virus's proteins, which the virus needs to make more of itself.
In addition, we've found that this special protein not only messes with the virus's ability to replicate but also stops the virus from using small molecules called small RNAs, which are typically involved in a plant's defense mechanism called PTGS (Post-Transcriptional Gene Silencing). So essentially, the Tm-1 gene's protein throws a wrench in the virus's plans on multiple levels.
Symptoms
More than a dozen viruses have been identified as infecting tomato plants, with symptoms depending on the variety, strain, and environmental conditions of each virus strain, along with the genetic background of its host plant.
"Manifesting typically as mottled leaves and stems and smaller, stunted fruits, the Tomato Mosaic Virus (ToMV) can cause significant damage to your garden."
"As one of the most tenacious tomato diseases, the Tomato Mosaic Virus (TMV) can persist for years in soil and plant debris, making it a challenging adversary for gardeners."
Tolerant of high temperatures, its spread primarily happens by mechanical means like handling plants or using infected seeds/grafting equipment; gardeners can become infected by touching tobacco products and infected plants/weeds.
Bean Common Mosaic Virus (BCMV) and Cucumber Mosaic Virus (CMV) have similar symptoms to ToMV but are transmitted through aphids instead of human handling or seed. Both strains of the virus can infiltrate all varieties of beans and other vegetable crops, such as Cruciferae.
If your tomatoes exhibit symptoms of mosaic, dig and burn them immediately. Also, ensure your garden remains free from plant debris to limit where viruses can hide; regularly sanitizing hands and tools after gardening to limit spreading it further to other plants; planting susceptible vegetables near tomatoes without first learning they're resistant is especially wise.
Diagnosis
Tomato mosaic virus causes plants to take on a green/yellow mottled appearance and be stunted, often featuring necrotic brown spots on fruit. The virus can be spread via handling or mechanical damage; gardeners infect their plants after handling tobacco products, infected tomatoes, or Solanaceae family weeds (potato, pepper, melons, and eggplant). Furthermore, insects carry and spread it via chewing, further spreading seed, grafting, and soil contaminations.
Symptoms depend on the strain, cultivar, age of infected plants, and temperature; infections can strike at any growth stage, but symptoms usually worsen with age. Pollination or water spraying is popular for spreading diseases to other tomatoes, peppers, and eggplants.
In contrast, viruses may even spread quickly through aphids, moving rapidly from plant to plant in an instantaneous cycle.
ToMV is a positive-sense single-stranded RNA virus belonging to the Tobamovirus genus of the Virgaviridae family with worldwide distribution. Its wide host range includes many important crop plants and weed species belonging to the Solanaceae and Cruciferae families, such as tobacco.
The ToMV genome encodes four proteins involved with replication and movement: 180K protein, 130K protein, methyltransferase/helicase protein, and 30K protein.
Prevention
The mosaic virus affects tomatoes of open-pollinated and hybrid varieties, causing symptoms on leaves and fruit that vary based on variety. Other crops affected by the mosaic virus include cucumbers, peppers, squashes, dahlias, apples, peaches pears. It spreads via infected seeds, insects, plant debris, or weeds.
Symptoms of the disease can include mottled and spotted leaves, stunted tomato plant growth, marbling patterns on fruit (particularly tomatoes), reduced yields, as well as its transmission by thrips, aphids, or other sucking insects as well as seed spread by infected plants or through direct contact between infected plants or via gardening tools contaminated by the infection.
Mosaic viruses don't spread by the wind like fungi or persist in soil or plant debris like bacteria, making prevention key in controlling mosaic viruses. Therefore, purchasing seed from reliable sources and treating it using 10% trisodium phosphate solution or heating it at 158 degrees is vital in controlling mosaic viruses.
Furthermore, transplants purchased from greenhouses that house other vegetables or perennial ornamentals may serve as reservoirs of viruses that spread the infection further.
Gardeners should avoid planting tomatoes near cucurbits, spinach, and other disease-prone crops to limit the spread of disease. Separating resistant varieties from susceptible ones will prevent aphids from landing on resistant ones and spreading disease to vulnerable ones.
Implementing a trap crop strategy where resistant varieties are planted at the field's perimeter while susceptible varieties are planted centrally may help limit this problem further.
Treatment
Tomato mosaic virus (TMV) is an international plant disease, inflicting mosaic infected leaves, stems, and fruit of tomatoes as well as related crops in the Solanaceae family, nightshade weeds in nightshade and pepper families, ornamentals as well as some ornamentals.
Plants become infected through normal crop handling practices or infected seeds; greenhouse environments should use resistant varieties and regularly steam sterilize tools and hands used in field or greenhouse situations to combat TMV.
TMV can be difficult to diagnose as its symptoms resemble other illnesses or nutritional deficiencies, making laboratory analysis essential. Thrips, aphids, or other insects that feed on infected tomato seedlings or fruit may spread the virus further and infect more seedlings with infected seeds and fruit, spreading its infection throughout other tomato seedlings or fruit as they feed upon them.
Symptoms of tomato virus diseases depend on age, environmental conditions, as well as the genetic background of plants. Their expression may also depend on which strain of virus causes it. Unfortunately, there is currently no treatment available in fields or greenhouses for this problem; gardeners should inspect tomatoes regularly and remove any that show disease symptoms to limit further spread.