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Tobacco Mosaic Virus – How To Protect Your Cannabis Plants

Tobacco mosaic virus (TMV) is a virus that was first identified in tobacco crops, but can impact other plants, including cannabis. While it cannot hurt the grower, it can significantly deform plants and lower yields. There is no cure. Here is how to spot it and what to do if you have infected crops.

Tobacco mosaic virus, as the name suggests, is a virus common to tobacco plants. TMV causes splotchy and twisted leaves, leaving a strange mottling or mosaic pattern in its wake. It can also slow growth and reduce yields. TMV was the first plant virus to be discovered.

Worse, TMV appears to have spread to other kinds of plants. These include tomatoes, peppers, eggplant, spinach, and marigold. It also appears that cannabis is susceptible to TMV. And although TMV cannot hurt the grower, it can prevent your plants from being successful.

SPOTTING SYMPTOMS

Plants with TMV have a very distinctive look to them. Leaves will be twisted and curved in ways unnatural to the plant. The leaves will also feature yellow stripes, spots, and a strange mottled, mosaic pattern.

Symptoms can be observed on several leaves or on just a few. Some plants are just carriers and never display symptoms themselves. It is also easier to see the leaf mottling if the affected plant is partly in the shade.

Specific visual cues that your plants have been infected with TMV include:

  • Strange leaf colour: Brown leaves with “burnt” edges, pale or yellow stripes in old and new growth, and dark purple or black patches are one sign. So is the yellowing of the leaves between the veins. A mottled, mosaic pattern is a major mark of TMV.
  • Stagnation in growth: Both old and new growth can be affected by TMV. If you plant appears not to be growing as it should be, it could be that TMV is slowing it down. Wilting is another possible sign of TMV infection, as is slowed root spread.
  • Abnormal growth: Leaves grow in a strange, twisted pattern. They also appear webbed, curling under or upwards in odd ways.
  • Strange Stems: The stems can be either significantly weakened or appear in strange colours like red or purple.
  • Anaemic buds: Your buds will not get nice and fat, but will stay small.

TREATING INFECTED PLANTS

So far, the incidence of this condition have not been proven – only reported – in cannabis plants. However, the news is not good if you suspect your plant has become infected. There is no cure. An infected plant will have TMV forever. Your main goal, in other words, is to find the infected plants and remove them from the grow. TMV appears to spread via contact. As viruses can also be present in pollen and seeds, they can live for a long time in a grow room. They can survive on grow room equipment, carpets, soil, and dead plant matter.

That is why it is also essential to immediately quarantine and remove any plant you suspect is infected, pronto. Be sure to fully sanitise all grow room surfaces of any TMV traces before starting your next grow cycle.

A NOTE ON PREVENTING INFECTION IF YOU SMOKE

If you smoke cannabis or tobacco, you run the risk of carrying the virus on your hands. As such, it is a good idea to always wash your hands before coming into contact with any plants.

TMV was the first plant virus discovered. It is now clear it can affect cannabis plants too. Here is what to look for.

Tobacco Mosaic Virus (TMV) in Cannabis Plants: Symptoms and Prevention

There’s no concrete evidence if the mosaic virus can indeed infect cannabis plants, although some growers swear it can. This happens because this virus is hard to come by and not everyone who suffers from it can test it in a lab and when the plants are tested, the results often come out as negative.

Some growers say the symptoms are similar but occur because of different factors that stress your plants and others are certain it’s the virus, despite everything, one thing is certain: you don’t want your cannabis plants to get infected.

1. What is the tobacco mosaic virus?

The tobacco mosaic virus (aka TMV) is a virus widely known for affecting tobacco crops and it’s said it has spread to a lot of different plants, including the cannabis plant.

The TMV is a virus that affects a plant’s development, this virus can live in contaminated tobacco products like cigarettes 1 , contaminated plants, soil or even in bugs that contaminate your plant when they chew on it. This virus can affect a cannabis plant development, affecting yields and the quality of the buds.

2. What does the TMV look like?

It’s impossible to see the virus itself because it’s a microscopic being, but if your plant is affected you will surely see the signs, even though some of the symptoms can be confused for other things, the mosaic pattern your plant will develop is unique and super easy to identify.

If your plants show signs of leaf discoloration make sure your plants indeed are infected with the TMV and are not showing signs of overfeeding or any other plant deficiency that result in yellowing leaves. The tobacco virus cannot be removed and by treating other problems you’ll be actually doing more damage.

3. Where is the TM virus found?

Because it’s a virus, it is inside the plant so you cannot see it, but there are several ways you can expose your plants to it.

Since it’s discovery, researchers have found out that the virus can infect more than 125 species of plants, and not only that, your plants can get infected if you plant them in infected soil or if a bug carrying the virus bites your plant, but the most common way of infection is plant to plant, by direct contact or via your hands after consuming tobacco products.

This means you have to be extremely careful when touching your plants after smoking tobacco because it’s the most common way most cannabis plants get infected.

4. Tobacco mosaic virus symptoms

The symptoms your plant shows after getting the TM virus will depend, the most common symptom 2 is a mosaic-like pattern on some part of the leaves, this alone won’t damage your plants but because there’s no way to remove it from a plant, this specific plant won’t be suited for breeding.

In more serious cases, you will see a mosaic pattern and some strange plant growth, this virus can cause the leaves to grow deformed, twisted and with a slower development, despite not damaging your plant, the unusual growth will affect the yields and depending on how your plant develops, it can also affect the quality of your harvest.

Mild Symptoms Severe Symptoms
Distinct yellowing of the leaves veins Plant deformation
Yellow spotting Stunted growth
Mosaic pattern on the leaves Twisted leaves

Have in mind that you plant can show both mild and severe symptoms at the same time, the signs your plant gives will depend on the strain and can vary from case to case, even though some symptoms like twisted leaves and deformation can be caused by other things, the unique mosaic pattern will help you identify if your plant has the tobacco mosaic virus more easily.

5. How to prevent it?

There’s no way to prevent the tobacco virus other than always:

  • Sanitizing your tools;
  • Buying soil or clones from a reputable vendor;
  • Washing your hands after smoking tobacco or dealing with infected plants.

This virus can infect your plants by simply touching them so the best way to prevent it is always washing your hands before working on your garden and always make sure everything you bring in your garden is safe.

6. How to deal with it?

Unfortunately, there’s no way to remove the virus, once your plant or soil is infected because viruses cannot be controlled once they have been transmitted, this is why your best option is to prevent getting it.

If your plants get infected you should remove them from your garden, this not only applies to cannabis plants because the TM virus can infect all other plants in your garden and once it has spread throughout your garden, you’ll have to get rid of all the plants so as soon as you spot it, it’s better to remove it, remember the virus can even be transmitted by hand so it’s not worth it to risk it.

7. In conclusion

Even though the tobacco mosaic virus won’t damage your plants like bugs do, it can become a vicious cycle, infecting all your plants around. It’s crucial you take care of infected plants as soon as you spot them and if you don’t want to remove them, maybe isolate them and always wash your hands and every piece of equipment you use before touching other plants.

If you have seen it on your crops or have important information to share with fellow growers, please leave a comment in the comment section below!

External References:

2. Tobacco mosaic virus – Rifkind, David & Freeman, Geraldine. (2005).

The TMV is hard to come by in cannabis but it can affect the development of the leaves with deformed growth and odd coloring, ultimately affecting yields.