Crawlspace color of wood question

The joists under this 1965 Dallas Texas home appear to have been sprayed with a clear yellow liquid. Note that the spray does not overlap onto the subfloor. The crawlspace has a dry history and does not look or feel like mold. It is not a pesticide I am familiar with. Any ideas?

it looks like treated yellow pine from Ohio…

John, it my be a left over treated joist.

Interesting. Almost all homes built prior to 1970 in Dallas were Douglas Fir. This does look like pine. Maybe this home was built after the 1965 marketing information. I see if I can research Ohio treated pine.

Thanks for the pine tip. I searched in my photos and found a DIERKS stamp. Seems it was a large pine supplier out of Arkansas and Oklahoma. Interesting history.