Tobacco Mosaic Virus (TMV) is one of the most persistent viruses that there is. There is significant economic loss from tobacco mosaic loss as nothing will control it and it is spread world wide. TMV is a very important disease as it was the first virus to be identified, and purified to homogeneity. Dead plant material found in the ground can harbor the TMV for over 50 years. Lets learn more about this virus and how to avoid it.
Ivanovski discovered TMV in 1892 however he did not discover that is was a contagious virus. It was in 1898 that Beijerinck made the discovery of TMV being a contagious virus.
TMV has been around for over one hundred years. And it only continues to get worse. Let me explain the symptoms to look for and what crops you will find it on. We will also discuss preventative measures so you do not get it. And we will cover the dreaded what to do if you have TMV on your plants.
The virus can appear in many different forms depending on the age and genetics of the plant. Typically there is mottling and mosaic of the leaves. There may also be yellowing, necrosis,and leaf curling of the plant tissues. As well as poor yield, and non uniform fruit color. All of these characteristics may vary according to the strain of the virus and the genetic background of the plant effected. Stem areas may become brown and brittle inside. Leaves may pucker. Plants generally start showing symptoms 10 days after contracting the virus. There are some plants that may show no symptoms at all.
TMV gets onto the plant by a host. The host may be you, an insect or a plant brushing up against another plant. There are many scenarios here. The interesting fact here is that the virus actually enters the plant through a minor wound. Sneaky little guy. And once the virus is in, the plant becomes infected and it is all over.
All solanaceous plants are effected. That would be peppers, eggplant, potato, and tomatoes. Other plants effected are beet, garden amaranthus, apple, apple-of-Peru, beans, bedstraw, figwart, fleabane, daisy, foxglove, galinsoga, New Zealand Spinach, nierembergia, nightshades, orchids, beggarticks, bindweed, black nightshade, browallia, buckwheat, bugleweed, butter-and-eggs, calendula, California bluebell, California rose, campion, evening, cape-gooseberry, cape-marigold, carpetweed, carrot, celandine, celosia, centaurea, chickweed, China-aster, Chinese forget-me-not, Chinese lanternplant, chrysantheumum, cleome, cowpea, cranesbill, Carolina, cress, currants (red and black), delphiniums, dock, dracocephalum, eggplant, elder, euphorbia, false jerusalem, cherry, gerneria, gilia, gloxinia, goosefoot (lambsquarters), grapevine, groundcherry, gypsophila, hawkweed, hedgemustard, helianthus, henbane, henbits, horsenettle, horseweed, hounds tongue, husk tomato, iberis, Indian tobacco, Jerusalem-cherry, Jimson weed, Kenilworth ivy, knotweed, kochia, ladysthumb, larkspur, lobelia, lunaria, lycium, malcolmia, marigold, (French), marshgrass, mesembryanthemum, Mexican-tea, morning-glory, mouse-eared chickweed, mullein, mustards, pear, pennyroyal, American, penstemon, peppers, peppergrass, petunia, phacelias, phlox, physalis spp., Pigweed, plantains, pokeweed, polygonums, potato, proboscis flower, purslane, reseda, ribgrass, salpiglossis, scabiosa, sheep sorrel, shepherds-purse, smartweed, snapdragon, solanums, speedwell, spinach, sugar beet, sunflowers, tasselflower, tobaccos, turnip, verbena (white), water-horehound, stalked, wisteria, zinnia, currant, grape, marigold, pear, and ,ornamentals, foxglove, petunia, delphinium, phlox, snapdragon and zinnia, and weeds of the amaranth and goosefoot families. To a lesser extent it effects muskmelon, cucumber, squash, celosia, ground cherry, impatiens.
TMV is transmitted by a number of means. First of all it may be seed borne. The seed that is saved from infected plants passes on the virus.
Secondly it may be transmitted by the hands of a smoker that has handled plants. If you are a smoker it is very important not to smoke in the garden and to thoroughly wash your hands with warm soap and water after smoking. The reason being the cigarette that you smoked may have been contaminated with the TMV virus and you can spread it to your plants just like that. TMV is a huge thing so please wash your hands instead of spreading it.
It can be transmitted by insects. Insects can pick up TMV off of weeds and infected plants and spread it to your plants. This is one reason to keep your garden free of weeds and keep the surrounding area free from weeds. The further the areas around your garden that you ca keep free from weeds the better. And the more proactive on insects the better.
People spread the virus. The virus is very stable, and just brushing up against a plant can spread the disease. Or you will touch one plant then another and spread the disease like wildfire. Believe me, I have seen it happen. You must be careful to remove plants that have the disease immediately and destroy them by bagging them and placing them in the garbage. TMV can persist in temperatures over 300 degrees F. This means that your compost is not hot enough to destroy the disease.
The plants will rub on each other and spread the disease. This is why it is important to remove any plant that looks like it has mosaic symptoms from the very first sign, or it will spread fast. This disease is very stable and spreads very fast. It is also suggested that you remove plants on either side of the TMV infected plant. The reason for this is that the TMV infected plant was rubbing up against the plants right next to it and insects can hop or fly right next to the next plant. Usually the plants adjacent to the infected plants will become infected if they have been touching. Remember how stable this virus is. Stick to the old adage, better safe than sorry.
Birds, squirrels and other mammals can spread TMV as well.
TMV is so stable that it will stay on surfaces such as benches, door handles and tools. Sanitation is very important.
1. Rogueing – Tag em and bag em. You need to inspect your garden or field on a routine basis. At least every 3 days. I have seen a mosaic go through a field of gardens and in a matter of 4 days go from a 40% crop loss to a 70% crop loss. This happened all because the people did not remove the infected plants as soon as they became infected. The minute you see a mosaic pattern, rip it out and throw it in the trash. If it is CMV, TMV, or any other mosaic, there is no cure and they all spread. The problem with TMV is it stays in the soil for at least 2 years. Why take chances? It is not worth it.
2. Certified Seed Lets start with the seed. Make sure that it is certified so that it is not infected with the TMV.
3. Treat Certified Transplants First make sure your transplants are from a certified reputable source. If you are putting nightshade transplants in you may want to dip them first in skim milk. Use 1/8 pound of skim milk per 2.5 gallons of water. Spray the plants to be translated to the point of dripping do this from 1 to 24 hours before planting. Dip hands in milk every 5 minutes while planting the transplants. The coat protein of the virus reacts with the protein in skim milk deactivating the TMV. This will not stop the disease, just protect the plants you are putting in.
4. Rotate Crops – You want to be careful that no nightshade family is in the same place for two years in a row.
5. Practice Good Sanitation – Clean tools after using them, wash hands frequently in the garden. Clean up debris in the garden and plow it under so that it can break down in the soil and not harbor insects.
6. Keep Insects at Bay – Insects are vectors for diseases. The way to help keep your garden disease free is to get rid of insects. Make sure to keep the insect population down. Plant a beneficial border,and interplant flowers.
7. Keep Garden Weed Free – Many weeds are hosts for viruses. The insects will feed in the weeds that have a virus and then take a bite from your well taken care of garden plant and transmit the virus. Keep out the weeds from inside and surrounding areas of your garden to fight off diseases.
If I Have TMV What Now?
1. Rip out all plants showing signs of TMV. Throw diseased plants in the trash. Compost is not hot enough to kill the disease. TMV has been shown to survive in temps of 300 degrees F. Daily or every 3 days inspect the fields for more plants showing signs. They will still keep coming for a while. After removing the plants wash your hand with soap and water and wash your clothes and shoes in hot soap and water.
2. It is a good idea to take out the plants that were on either side of the infected plant especially if they were touching. If they were touching they most likely were infected but are not yet showing signs. This is a good way to get control early before TMV takes control.
3. Make sure to pick up plant leaves and don’t leave anything behind get it all in the trash. You do not want particles of TMV resurfacing after you have it all cleared up.
4. Decontaminate all tools, stakes and garden equipment after using them on infected plants you do not spread the virus. This includes your watering wands. Bleach does not work for the virus. Soak the tools in boiling water for 5 minutes. Afterwards scrub with a strong detergent. Dawn or HEB brand of Dawn is biodegradable and is quite inexpensive for this purpose and has no phosphates. Tomato cages and other structures can be washed in a strong solution of detergent, rinsed and left to dry in the sun. Leave them out in the sun for a week as the sun will help degrade the virus on the metal.
5. Wash your hands, shoes, clothing thoroughly with hot soap and water. TMV is very stable. Be careful not to let the hose nozzle touch plants or it will spread virus.
6. Do not plant anything in the solanaceous family in the same spot for one year. Rotate the following year with another crop that is not susceptible to TMV and one that is resistant. The suggested rotation after solanaceous
crops is corn, rice or small cereal grains. These crops do not carry TMV.
7. Two years after you have pulled the plants you are able to plant solanaceous crops in the same area again. It is suggested that you use varieties that are resistant to TMV as there still could be residue in the soil. Here is a link that will give you the low down on most of the varieties of seeds. If you are looking for a particular seed variety that is not on here call the seed company that is listing the seed as they should have all of the information. The rule of thumb is that most of the seeds that are going to be TMV resistant are going to be hybrids.
8. When planting anything in the solanaceous family make sure that the seed is certified disease free. If the seed is 2 years old and is not fresh that helps as well.
8. If there is any residue on the surface from plants at this time make sure to plow it deeply under the earth so that it is not exposed and it will break down.
9. Ferment, wash dry and treat seeds in hot water at 122 degrees F for 25 minutes before planting them. Or treat the seeds with 15 % trisodium phosphate for 2o minutes, or 2 hours of 10% trisodium phosphate solution,changed out after 30 minutes to a fresh solution, rinse and let dry. Or you can incubate the seeds at 158 degrees F for 2 to 4 days.
10. When planting your transplants from the solanaceous family it is a good idea to dip them in a skim milk solution and wash your hands in skim milk as well. Use 1/8 pound of skim milk per 2.5 gallons of water. Spray the plants to be translated to the point of dripping do this from 1 to 24 hours before planting. Dip hands in milk every 5 minutes while planting the transplants. The coat protein of the virus reacts with the protein in skim milk deactivating the TMV. This will not stop the disease, just protect the plants you are putting in.
11. Take a deep breath. It is possible to get through this, you can make it!