Yokes still in use?

I have heard it claimed that Justin Martyr wrote that Jesus made plows and yokes, and that during Justin's life some of these were still in use. I heard this again recently, with a gloss about how good the quality must have been, and wondered where I'd missed that--I'd thought I'd read all of Justin Martyr's surviving work.

Google pointed me to many references, of which the oldest I found (sorry, I didn't wander through them all) was The Jewish Encyclopedia, Volume 7, 1916, which reads

"It it known that he earned his living by his father's trade, that of a carpenter; according to Justin Martyr, plows and yokes made by Jesus were still in existence at his (Justin's) time, about the year 120 ("Dial. cum Tryph. %88)."

The reader is invited to read that passage from the Dialogs, but the relevant portion is

And when Jesus came to the Jordan, He was considered to be the son of Joseph the carpenter; and He appeared without comeliness, as the Scriptures declared; and He was deemed a carpenter (for He was in the habit of working as a carpenter when among men, making ploughs and yokes; by which He taught the symbols of righteousness and an active life)

If you want to search the whole list of Justin's works in one chunk, this OCR version is available, warts and all.

My best guess is that somebody quoted some lost works of Justin. Or perhaps one of the falsely attributed ones that isn't part of the current list. Or possibly one of the scholars contributing to the Encyclopedia screwed up, and the error has persisted via unquestioning quotation. Or perhaps both my memory and my keyword-fu failed me.

I have asked a couple of real patristics scholars to help out, and will update this with any more expert answers.

UPDATE: Or maybe the Latin translation they worked from was ambiguous?