Mosaic Viruses

How to Identify, Control, and Prevent Mosaic Viruses

Mosaic Virus

Here are tips on how to identify, control, and prevent mosaic viruses on a variety of plants.

What Are Mosaic Viruses?

Mosaic viruses affect more than 150 types of plants, including many fruits, vegetables, and flowers. The disease is characterized by leaves that are mottled with yellow, white, and light or dark green spots and streaks (in other words, a “mosaic” of these colors). Some of the most commonly infected plants include tomatoes, squashes, cauliflower, and cucumbers, but many more plants are susceptible.

Types of Mosaic Viruses

There are a number of mosaic viruses that commonly affect plants in the vegetable garden, including:

  • Bean Common Mosaic Virus (BCMV) and Bean Yellow Mosaic Virus (BYMV) are the primary mosaic viruses that affect beans of all types. They are typically spread by aphids, but BCMV is also seed-borne, so do not save seeds from infected plants. 
  • Cucumber Mosaic Virus (CMV) is one of the most common types of mosaic viruses and tends to be spread by aphids. As can be inferred from its name, cucumber mosaic virus often affects cucumbers, but it is also a common problem for many other garden plants, including other cucurbits (melons, squashes), nightshades (tomatoes, peppers, eggplants, potatoes), and leafy greens (lettuce, spinach).
  • Tobacco Mosaic Virus (TMV) spreads through seeds and direct contact, and the best way to avoid it is to grow resistant varieties. 


How to Identify Mosaic Viruses and Damage

Viral diseases are difficult to identify because symptoms vary from plant to plant and may also vary depending on the age of the plant and its growing conditions. However, the most common ways of identifying mosaic viruses are listed below.

  • The leaves are mottled with yellow, white, and light and dark green spots, which appear to be elevated. This gives the leaves a blister-like appearance.
  • Plants are often stunted, or they grow poorly.
  • Plants may have other deformities and their leaves may be crinkled or wavy. 
  • Cucumber mosaic virus: Infected plants are stunted and often exhibit “shoestring sydrome,” which is a characteristic malformation in which the edges of the leaves fail to develop, with the leaf veins developing as long, narrow strips. Tomatoes are small and misshapen.
  • Tobacco mosaic virus: Infected plants have mottled and yellowed leaves and twisted or deformed young growth.

Photo Credit: University of California. Cucumber mosaic virus causes severe damage and discoloration to a spinach plant.

Control and Prevention

How to Control Mosaic Viruses

Once plants are infected, there is no cure for mosaic viruses. Because of this, prevention is key! However, if plants in your garden do show symptoms of having mosaic viruses, here’s how to minimize the damage:

  • Remove all infected plants and destroy them. Do NOT put them in the compost pile, as the virus may persist in infected plant matter. Burn infected plants or throw them out with the garbage.
  • Monitor the rest of your plants closely, especially those that were located near infected plants.
  • Disinfect gardening tools after every use. Keep a bottle of a weak bleach solution or other antiviral disinfectant to wipe your tools down with.

How to Prevent Mosaic Viruses

  • Plant virus-resistant varieties in your garden. Resistant varieties of tomatoes have yet to be developed for cucumber mosaic virus, but tomatoes that are resistant to tobacco mosaic virus may have some slight resistance to cucumber mosaic virus as well.
  • Mosaic viruses are mostly spread by insects, especially aphids and leafhoppers. You can try covering your plants with a floating row cover or aluminum foil mulches to prevent these insects from infecting your plants. Look at our other tips for controlling aphids.
  • Control your weeds. Some types may serve as hosts for the disease, and when aphids and other insects feed on these plants, they will spread the viruses to your garden plants.
  • To avoid seed-borne mosaic viruses, soak seeds of susceptible plants in a 10% bleach solution before planting.


Reader Comments

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Care of the soil is the most

The Editors's picture

Care of the soil is the most important part of gardening and the best way to prevent pests and diseases (although your plants may succumb to something, despite your best efforts).
With all plant residue removed, apply compost or aged manure in fall, plant a cover crop, and and practice rotatation and companion planting next year. Planting resistant varieties can also help.
For additional advice, see the response immediately below this one.

All of our squash and

All of our squash and zucchini plants have mosaic virus. Is it ok to plant more in the same soil or do we need to start fresh?

First, you should remove and

The Editors's picture

First, you should remove and destroy the infected plants. Though you can plant in the same soil, you may want to consider planting elsewhere as any pests that were feeding on your plants will be carrying the virus and can spread it again. Mosaic viruses are mostly spread by insects, especially aphids and leafhoppers. You can try covering your plants with a floating row cover or aluminum foil mulches to prevent these insects from infecting your plants.

I have a Bonnie Golieth

I have a Bonnie Golieth tomato plant that was doing great until 2-3 weeks ago. The leaves are curling upward and some leaves are turning a little brown. It isn't growing any taller or bushier, but I don't see any bugs. I have no tomatoes or flowers on the bush now. What's happening?

Curled leaves are indeed a

The Editors's picture

Curled leaves are indeed a symptom of some tomato viruses, however, you would probably be seeing yellow-green mosaic patterns on the leaves or more mottled leaves, not just brown tips. What's the weather like? Leaf curl and slowed growth also happens in very hot, dry weather with high heat; the plant curls its leaves to conserve moisture. If it's a virus, there's not much you can do. If it's weather and environmental, give it even moisture, cool it down with mulch and perhaps a shade cloth, avoid over fertilization, and do not prune it.

I am seeing mottling in a few

I am seeing mottling in a few (out of roughly 30) of my sunflowers. My question is, would mosaic virus only show up on a few of the leaves or be consistent throughout the entire plant? The plant looks otherwise very healthy and growing well. Have I just caught it early? I do not want to risk the rest of my garden. Thank you!

Mottling is certainly one of

The Editors's picture

Mottling is certainly one of the manifestations of mosaic virus. As noted above, there is no fix, so you would be best to destroy the stricken plants. If possible, you should consider planting virus resistant varieties in future and, of course, maintain good soil and growing environment.

I am growing organic squash

I am growing organic squash and zucchini on my deck in pots planted in organic potting soil. They have become infected with a mosaic virus. I know I must throw away the plants, but should I also throw away the soil? I do not want any future plants to become infected. How should I dispose of the soil if I need to get rid of it? I don't want to spread a virus to the plants in my garden.

My tomato plants started out

My tomato plants started out great, and one started turning yellow at the bottom. Over a period of about two weeks it gradually spread up to the top. Adjacent plants started the same cycle. Got a lot of green tomatoes, but some have blossom end rot. The affected plants look awful. It appears to be affecting my whole crop in different stages. Is it a virus? Can I save them?

Mickey, You are not alone

The Editors's picture

Mickey, You are not alone (though that may not be much consolation). We just answered this question. See right below.

Our tomato plant leaves are

Our tomato plant leaves are turning yellow from the bottom up. Why?

When the tomato plant turns

The Editors's picture

When the tomato plant turns yellow and starts dying from the bottom up, the plant usually has a fungal disease: either early blight or leaf spot. Often, these diseases are due to too much water from rain or overhead watering. Only water at the base of the plant. Keep leaves dry. Water in the morning. Also, make sure the plants are not crowded and have good air circulation. Ideally, there should be enough room that you could walk around each tomato plant (not that you would). Mulch your tomato plants to control moisture. Be sure to cage or stake well to keep leaves off the ground. Clean up all debris. It can be helpful to provide a fungicide spray weekly, before rain, or at onset of disease before it's too late.
Copper-based fungicides are considered organic. Speak to a local nursery for brands approved in your area.

I have pumpkin plants and I

I have pumpkin plants and I noticed that my plants have white spots and there looking like the leafs are turning white i and on one of my pumpkin plants I had black and moldy looking stems I pull thises up but what is wrong with my pumpkin??

Hi, Atonya, It soulnd like

The Editors's picture

Hi, Atonya,
It soulnd like powdery mildew, an air-borne disease. You can purchase organic suphur and make a tea with it, them spritz the plant/s; that should kill the mildew.
Several sources suggest that if your plant has established fruit (pumpkins)—that they are growing— they have a good chance to mature, even if all of the leaves turn black and wither.
In future, consider getting mildew-tolerant/resistant varieties. Quite a few, but not all, cultivars are listed here:

My squash and zucinni and

My squash and zucinni and eggplants are growing well with many flowers. However, they are not producing fruits. I notice particularly on the egg plant that the leaves have many hole (no indication of worms or insects on the leaves) and a number of stems appear to have been cut off and removed. The plants are about 4 weeks old, and were transplanted into newly tilled soil with a lot of worms in the soil and added garden soil. They were fed just this past week. Also my tomatoes appear to be growing too fast and are spliting. We have had some periods of 2" or greater rains and then several week of no rain. I am watering with a soaker hose about a half hour twice a day when not raining. Any suggestions?


After reading many comments I

After reading many comments I need to ask this question to be sure if I am reading right. Can mosaic virus spread to other crops? Another words, if my cucumber plant is affected and I have pepper plants near the cucumbers, it can spread to the peppers? Please respond.

Hi Alex, Yes, the virus can

The Editors's picture

Hi Alex,
Yes, the virus can spread to your peppers. Insects spread the virus as they move from plant to plant. If your cucumber plants have the virus you should remove and destroy them. Controlling the insect pests in your garden is the best preventive control of mosaic virus.

tobacco virus

My landlord lets me help in the garden and share the harvest. I smoke, but never until the evening when I read. He is scared that I will infect his plants. I assured him I bathe before I go out into the world and I never handle tobacco until the evening, in private,. Is this enough?

I planted my spring garden

I planted my spring garden approximately four weeks ago (five 4x8 raised beds0. Everything looked great but I noticed some mosaic yellow splotches on my zucchini last week. Now after a week it has spread to everything including tomatoes, cucumbers, and melons. The plants look healthy with only a few leaves around the bottom with the yellow. If I keep removing the mosaic leaves is there a chance to stay on top of it? Or since it is early in the year should I bag it and start all over again? I have placed white fly strips and have used some spinosed with some other aphid controls. Is it too late?

It's best to remove and

The Editors's picture

It's best to remove and destroy the plants. They will not produce well and any fruit will taste bitter.

My hydrangia bush, camellia

My hydrangia bush, camellia tree and geranium seem all infected by mozaik virus and I need to cut them first in order to get rid of them. I heard that we need to clean the clipper after cutting the virus infected plants. How should I clean them? Just using water is good enough or any special soap to use?

Dear Staff, I was growing

Dear Staff,

I was growing beans in pots outside on a roof. They became infected with mosaic virus so I uprooted them and threw them away. What crop or flowering plant that is resistant to the virus can I replant in that same soil?

Mosaic virus is on the of the

The Editors's picture

Mosaic virus is on the of the most common afflictions of crops. It is transmitted by insects.
Change the soil. Start fresh.
Mosaic virus spreads most commonly from contaminated hands and tools. Place tools in boiling water for 5 minutes and then with wash with a strong detergent. (A dip in bleach is not an effective decontamination.) Wash your containers, too.
After handling contaminiated materials, always wash hands before handling healthy plants.
For better results, plant resistant varieties. And rotate your crops, even in containers.

My cucumber plants were doing

My cucumber plants were doing great until about 2 weeks ago, the leaves started dying off. Progressively got worse, now just about all of the leaves are white or dead. The vines look ok and the cucumbers that were started are still growing, slowly. First year and I was told to water at night, now I have learned to water in the am and to avoid the leaves. Did I kill the plant by watering at night and soaking the leaves? Or do they have a virus, my beans are next to the cucs but they are growing like crazy. I'm in CT so I think it's too late to try again. I'm wondering if I should not grow in the same area as these plants next year- it's a raised bed.

You may have powdery mildew

The Editors's picture

You may have powdery mildew disease. Try using an horticultural oil spray or mix milk and water in a spray bottle and use it on your plants. Use 3 parts milk to 7 parts water. Milk has been proven effective against powdery mildew.

Hi, I think my cucumber plant

Hi, I think my cucumber plant may be infected, and it is close to my bean plant (climbing vine variety). Can my beans get this virus?

Unfortunately, the cucumber

The Editors's picture

Unfortunately, the cucumber mosaic virus can be transmitted to your beans.  It's carried by aphids. You will need to destroy any infected plants and avoid planting these crops in the same space next year.

i have the problem with my

i have the problem with my eggplant because of mosaic virus! the eggplants which is covered by plastic mulch and equipped with drum drip irrigation are infected by the Mosaic virus and Aphids. Is there any correlated between plastic mulch and Mosaic virus?

We do not know of a

The Editors's picture

We do not know of a correlation. Eggplants respond favorably to being grown on plastic mulch with drip irrigation. According to our extension office, "Winged aphids are repelled by silver- or aluminum-colored mulches. If there is a probability of severe virus pressure, place reflective polyethylene mulches on planting beds before seeding or transplanting to significantly reduce rate of colonization by winged aphids and delay the buildup of damaging numbers of aphids by 4 to 6 weeks. While this approach is mainly effective in delaying or reducing the incidence of virus diseases transmitted by winged aphids and whiteflies, reflective mulches can also delay the buildup of wingless aphids that arise as a result of colonization by winged individuals. The mulches lose their effectiveness when more than 60% of the surface is covered by foliage or if the mulch becomes fouled with dust or soil. Therefore, they are effective only for the first few weeks after transplanting."

Mosaicvirus control

Groundnut oil 10ml/litre of water plus emulsifier for oil and water mix and any micronutrients plus boron you will get 100,%
Control in 2sprays



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