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

There is nothing that you can do once your plants have been infected. Prevention of insect infestations and sanitation practices galore go a long way in preventing the spread of the disease.

There are a number of possible explanations for what you describe other than CMV. Herbicide drift is one. Can you possibly post a picture? CMV is an aphid vector disease (assuming non-infected seeds). Do you see aphids on the plants? Do you know if CMV is a common problem in your area? But yes, IF it is CMV then get rid of the plant ASAP. However, IF it is CMV and if you have aphids then it is likely the other plants are already infected too. Given that consideration, personally I would be inclined to wait a bit and see what develops since the odds are that it is NOT CMV. Its your choice. See the link below for better pics and all the details on CMV. Dave Here is a link that might be useful: CMV

Looks like herbicide damage. Tomatoes are very sensitive, more so than many other plants.