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Mosaic Viruses

What are mosaic viruses? This virus infects more than 150 types of plants, including many fruits, vegetables, and flowers. It is characterized by leaves mottled with yellow, white, and light and dark green spots or streaks. Some of the most commonly infected plants include tomatoes, potatoes, squash, and cucumbers. 

How to Identify Mosaic Viruses

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. 

How to Control Mosaic Viruses

Once plants are infected, there are no controls. Remove all the infected plants and destroy them.


  • Plant resistant plants when available in your garden.
  • 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.
  • Control your weeds. Some types may serve as hosts for the disease.


My tomato plants first turned

By LaTha

My tomato plants first turned yellow and then wilted and now have purple coloring on them and some leaves have holes. The zinnia and sunflower in the adjacent pot also seems to have been infected. However, the tomatoes are very small but do ripen. My question is: Is it safe to eat the tomatoes from this plant (assuming it is infected based on above responses) if thoroughly washed and cooked in heat?


After removing infected

By Helen Setterfield

After removing infected plants, what about the soil in raised planter beds? Does mosaic virus overwinter in the soil to infect the following year as well? Is there any preventative that is effective?

Care of the soil is the most

By Almanac Staff

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

By elizabeth b

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

By Almanac Staff

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

By Marie Martinez

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

By Almanac Staff

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

By sandandsun

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

By Almanac Staff

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

By Lisa A. Brown

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

By Mickey Reeves

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

By Almanac Staff

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

By Jane H.

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

When the tomato plant turns

By Almanac Staff

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

By atonya

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

By Almanac Staff

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

By Alex Figueroa

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

By Almanac Staff

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.

I planted my spring garden

By Julie Toledo

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

By Almanac Staff

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

My hydrangia bush, camellia

By Kaori

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

By Aviel

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

By Almanac Staff

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

By Teri Schutte

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

By Almanac Staff

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

By AmberH

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

By Almanac Staff

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

By phearen

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

By Almanac Staff

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."

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