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I went to water my tomato plants this morning and noticed that much of the most recent leaf growth was covered in black dots. As can be seen in the following photos.

Side view of tomato plant with new leaf growth covered in black dots. Top view of tomato plant with new leaf growth covered in black dots.

Note that the drops of water on the plant foliage is from morning dew, not from overhead watering.

The black dots were not there last evening and they are not dirt from splashing water. I sprayed a watery mixture of Dyna-Gro neem oil and Dr. Bronner's unscented pure-castille liquid soap two evenings ago. There has been no precipitation, other than morning dew, since I sprayed. I've been spraying every seven days since before these tomato plants were transplanted.

I have read that a spider mite infestation can appear as hundreds of little black dots, but there are no signs of webbing and these black dots appeared in the course of eight to ten hours. I have occasionally spotted and removed winged aphids and ants carrying aphids from these tomato plants. But I've never noticed more than three visible aphids in one day. I have used food grade diatomaceous earth in the past, to try and curb the ants, but I do not want to harm any beneficial insects.

What could this be and does anyone know of a recommended treatment?

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It looks like it's either damage from thrips or tomato spotted wilt virus (which thrips can spread). I don't see any wilting, though (so maybe it's just the thrips). See this post on Tomatoville about tomato spotted wilt virus, which shows a picture similar to yours.

If it's a virus, I don't know of anything you can do about it (other than pulling the plants or embracing the virus). Thrips are said to be a challenge, too (and although I don't know much about handling them, there's probably information online if you do a web search).

In future, you could try planting varieties that are resistant to the virus (there are some out there: e.g. Sungold F1, Tycoon F1, BHN 444 F1, Bella Rosa F1, etc.)

Thrips can do damage that looks like spider mite damage.

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    You’re right it is thrips, I saw some of them today. I hope it’s not also the virus, but if it is I’ll just embrace it. Thank you for the info, I’m going to go research how to deal with the thrips. – Jonny Henly May 20 at 19:31

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