tomatoes with Mosaic virus/tobacco virus

jeembeauxMay 3, 2013

This year I ordered some heirloom tomato plants from a company with a good reputation. The plants came in looking fine, but one of them had leaves that looked strange... curling in a weird way. I attributed it to it being an heirloom that I wasn't familiar with. I got the plants in February and kept them in my hydroponic grow room under metal halide and fluorescent lights. They did fine, and I planted them around Easter.

Now, several of the plants have that strange curl and "fern" look to them - tiny leaflets, spindly leaves. Some of the plants also have black spots on the leaves with halos around the leaves. In some areas, there is bright green/yellow discoloration on parts of the leaves. All of these symptoms indicate the two viruses I mentioned in the subject.

I removed two of the plants from my raised beds. These are new beds with new soil I made myself based on the Square Foot Gardening recipe.

I know there's basically no cure for this condition, but I'm wondering how badly this will affect my harvest?

I'm also wondering about using the same bed next year for tomato plants, as I've read that the virus can exist in the soil for 100 years.

Questions:
Am I stuck with never using this soil for tomatoes again?
How badly will my harvest suffer?
Is moving the plants to a different part of my back yard sufficient, or do I need to destroy them?
How likely is it that all my tomato plants are infected? I have around a dozen plants and hate to think that I need to destroy them all. They're all growing well.

Thanks!

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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

First, TMV (tobacco mosaic virus) is essentially non-existent in the US and has been for decades. CMV (cucumber mosaic virus) still occurs, appears somewhat similar, and can affect tomatoes.

However, even without seeing a picture of the plants, the odds of either virus are 99% unlikely.

The most common cause of the symptoms you describe is NOT a virus but exposure to herbicides. That would be supported by the fact that this is a new soil bed. that the plants were fine until they went outside (so the supplier sent healthy plants),

Every year at this time of year when herbicide use is at its heaviest we get many posts over on the Growing Tomatoes forum with descriptions of plants identical to your description.

Herbicides, if you haven't used any, damage can result from drift from as far as a mile away and in most cases is from city or a neighbor spraying. It can also be brought in in contaminates mulch/compost.

Depending on the amount of exposure many plants will recover so Investigate those sources before writing off your plants and garden.

And if possible post some pictures of your plants focused on the damaged foliage.

Dave

    Bookmark   May 3, 2013 at 12:47PM
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Desireea3

Could this be because of what you mentioned Dave, I added cedar to my plants to try to keep the ants and flies away and the neighbors recently had the front yard sprayed the ants were so bad and within the week they spots have come out on my zucchini, tomato, and bean plants. The plants still look healthy though no drooping or wilting.

    Bookmark   May 3, 2013 at 1:05PM
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torquill(z9/sunset15 CA)

I disagree... herbicide damage rarely causes spots on the leaves, and the yellowing tends to be a general overall thing (especially on the growing tips), not mottled. It's always easier to figure out with a picture, but a virus is possible.

TMV is, indeed, almost nonexistent outside of labs in the US. Cucumber Mosaic Virus, on the other hand, is out there, and may be more common than you think (many Heavenly Bamboo plants carry it; the resulting red color is considered desirable). There is also Tomato Spotted Wilt Virus, which is rampant in many parts of the country. Both CMV and TSWV are vectored by insects; they are the major viruses we usually run into in tomato plants. They can strike individual plants, leaving neighbors alone.

If you're dealing with an herbicide, the effects will show up on neighboring plants which are close to each other and sharing the bed, or different species of plants that share the same soil/exposure, like squash or peppers (but not necessarily every kind of vegetable). The plants might pull out of a light exposure once the source of herbicide is removed; the best sign is when they start to grow again. Badly herbicide-damaged or virus-infected plants will stop growing or slow to a crawl, and will never start again.

Am I stuck with never using this soil for tomatoes again?

No. Any virus you are likely to encounter in tomatoes doesn't persist in the soil. If your soil is contaminated with herbicide (and I can't imagine how you would manage that with Mel's Mix, unless the compost part was badly contaminated) then you will have to get rid of it, but not if the herbicide drifted over from elsewhere.

How badly will my harvest suffer?

Virus-infected plants will not bear, or will bear misshapen and often bad-tasting fruit. Since you're not likely to get any good fruit out of these plants once the virus is well established, you'll have fewer plants to harvest from.

If herbicide-damaged plants recover, they will be set back by at least a few weeks, but the fruit you get after that should be fine.

Is moving the plants to a different part of my back yard sufficient, or do I need to destroy them?

If it's a virus, you need to pull them. CMV and TSWV are transmitted by insects which can fly, and infected plants can serve as a reservoir for insects to infect your currently healthy plants. (Besides, they won't fruit well, so why keep them?)

If it's herbicide damage... well, if the soil isn't the problem, and there's no new drift from elsewhere, then there's no real point to moving them. Either they'll pull out or they won't.

How likely is it that all my tomato plants are infected? I have around a dozen plants and hate to think that I need to destroy them all.

I've gotten a few virus-infected plants over the years; once I confirm that it's a virus rather than some quirk of weather or genetics, I pull the (usually single) plant and look for the same symptoms on other plants. Out of three years I've had a virus problem, I've had to pull four plants total, and I grow over 15 plants a year. So keep your eyes peeled, and if you're lucky, it might turn out to be just a couple.

They're all growing well.

Now this is what confuses me. Is it just the normal-looking plants that are growing well? If so, cross your fingers and leave them be. If the shoestring-leaf ferny plants are also growing "well", as in vigorous and putting out lots of new growth, digdirt may be onto something with his herbicide theory.

Here's a few pics to help out:
Cucumber Mosaic Virus

Tomato Spotted Wilt Virus

--Alison

    Bookmark   May 3, 2013 at 11:11PM
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Michael

Hey digdirt, you and the OP might want to check out the link to see Cornell's opinion on the subject.

I'm not being a snot about this, it's just been a long time since I was in hort. school so I did a little digging to refresh the memory.

Hope you all enjoy lot's of salsa and tomato sauce!

Here is a link that might be useful: TMV literature

    Bookmark   May 4, 2013 at 6:00PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Hey digdirt, you and the OP might want to check out the link to see Cornell's opinion on the subject.

Yep, never said it wasn't listed or discussed or that it doesn't still exist in other parts of the world.

Note date on the Cornell article - 1984. That is the standard outdated info provided by many sources on the disease.

But since the virus has been all but eradicated in all tobacco varieties grown in the US since the N gene introduction into all commercially grown varieties in the late 70's, TMV poses no threat to crops in the US unless one wants to illegally import tobacco from foreign countries.

Cornell is a great source of information on many things but it is also very outdated in some areas so it's important to explore alternative sources at times. If you want to read more about TMV and tomatoes there are many discussions with scholarly links included over on the Tomatoes forum here.

________________

herbicide damage rarely causes spots on the leaves

Agree but it does produce "leaves that looked strange... curling in a weird way". Plus these plants were grown indoors since February - more than ample time for any virus to have developed if the plants were contaminated when purchased. Then planted into a new bed with fresh soil. Be real difficult to pick up a virus under those conditions unless the new soil was contaminated.

But as I said above, it's just a possibility given no picture, the little information given, and the preponderance of herbicide damaged plants at this time of year.

Dave

    Bookmark   May 4, 2013 at 7:01PM
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jeembeaux

Here are two photos showing the damage I mentioned.

    Bookmark   May 7, 2013 at 9:16AM
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torquill(z9/sunset15 CA)

That looks like two problems: herbicide damage and (squint) bacterial speck, probably. While it is possible to get that scrunched-veins effect with CMV, it's much more common with something like 2,4-D (aka weed'n'feed). CMV tends to make the leaves much thinner, almost like strings.

So the good news is that the plants might be okay if you can find out how they got dosed, and make sure they don't get any more. :)

--Alison

    Bookmark   May 11, 2013 at 5:57PM
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jean001a(Portland OR 7b)

Agree w/ the herbicide suggestion. Likely culprits (active ingredients) include these:
1. 2,4-D
2. manures or other organic matter contaminated with clopyralid or one of its close relatives.

see this http://puyallup.wsu.edu/soilmgmt/Clopyralid.html
-- if you think this may be the problem, look for the how-to info for doing a bio-assay to confirm or not.

Here is a link that might be useful: clopyralid herbicide contaminated soil

    Bookmark   May 11, 2013 at 7:52PM
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