We’ve still got tomatoes on our minds. 

In last week’s blog post, we covered tips for organically preventing & treating 11 common tomato plant diseases.

Our tomato disease prevention series continues this week as we cover how to organically prevent your tomato plants from tomato spotted wilt virus (TSWV) and cucumber mosaic virus (CMV).

These two viruses can do some serious damage to your tomato crop, so keep reading to find out how to protect your plants from these pesky viruses!

(Another special thank you to our former Ag Extension agent, Amy Dismukes, for providing us with these resources on tomato diseases! Her wisdom has guided us in this post.)

Tomato Spotted Wilt Virus (TSWV)

Though this virus’ name would suggest otherwise, tomato spotted wilt virus is a danger to more than just tomatoes. 

Threatening other produce like peppers, potatoes, lettuce, onions, and even herbs like peppermint, TSWV is a concern for any gardener. Fan-favorite flowers like begonias can also become victims to this disease.

You’ll notice symptoms on leaves, petioles, stems, and fruit. The severity of these symptoms will vary depending on what stage of infection your plant is at.

Young leaves may show small, dark-brown spots that eventually lead to the leaves’ demise. Dark brown streaks may appear on stems and leaf petioles. Infected growing tips usually exhibit stunted growth.

Immature tomato fruit on an infected plant will appear mottled with light green rings featuring raised centers. Mature fruits will have patterns of orange and red discoloration.


Unfortunately, if your tomato plant is struck by TSWV, it’s a goner. There’s no way to treat a plant with tomato spotted wilt virus.

However, there are several preventative measures you should take to control thrips—the insects that transmit tomato spotted wilt virus.

Weed, weed, and weed some more. Ensure that your garden is free of weeds that thrips are attracted to. This includes chickweed, buttercup, dandelion, sowthistle, and plantain. Not only do they attract thrips, but they are also susceptible to TSWV.

Beneficial insects are an organic defense against pests like thrips. Pirate bugs and big-eyed bugs are two predator bugs that take a liking to thrips.

We have ordered beneficial insects from Arbico Organics  for our Summer U-Pick Garden and found the beneficial insects to be high quality.

Read more about beneficial insects here.

Cucumber Mosaic Virus (CMV)

Just like the tomato spotted wilt virus doesn’t target only tomatoes, the cucumber mosaic virus (CMV) doesn’t only infect cucumbers. Peppers, spinach, lettuce, beans, and, of course, our beloved tomatoes are at risk for CMV. In fact, more than 1,200 species of plants can be infected with CMV.

More than 80 types of aphid species can transmit the virus between plants.

Fortunately, this virus is not seed-borne, nor does it remain in plant debris, in soil, or on your hands. This makes it simple to remove infected plants from your garden without fearing infected plant debris will spread to next season’s crops, like tomato fungi does.

Keep in mind, though, that the virus can overwinter in other living plants, like weeds. This is why weed control is an important part of fighting this virus.

Spotting CMV is relatively easy. A shoestring-like leaf blade is a classic symptom. These symptoms can be transitory, and the symptoms don’t spread in an orderly fashion. Older and newly developed top leaves may show severe symptoms, while middle leaves may appear normal.

Though no seed-borne, cucumber mosaic virus can also be found in greenhouse plantings. Greenhouse infections are often due to seedlings being grown outdoors, left unprotected from the virus host, and then moved indoors, with early infection going unnoticed. 

Plants that are severely stricken with cucumber mosaic virus produce very few fruit. If they produce any, these are small and often mottled.


The prognosis for tomato plants infected with cucumber mosaic virus is the same as tomato spotted wilt virus: there is no treatment.

Additionally, no CMV-resistant tomato varieties currently exist.

But all is not lost! You can take proactive steps to prevent CMV infection.

Avoid planting your tomatoes near weedy border areas. Practice the same weed care for prevention as TSWV.

Consider isolating your tomato plants by growing taller, non-susceptible barrier crops around your tomato plot, like corn. 

To control those evil aphids without the use of chemicals, we recommend sourcing beneficial insects for your garden. Green lacewings are a great option, as their larvae feed on aphids. 

Entice your green lacewings to stick around by planting buckwheat and cosmos, to companion plants that attract beneficial insects like green lacewings.

We order our green lacewings from Arbico Organics.


ARE YOU A VISUAL LEARNER? If so, I am happy to send a presentation via email which contains pictures that Amy Dismukes provided us on the diseases. Just click here to request the presentation.