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.
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?