Welcome to the board jx.
There has been some discussion as to whether using leaves from the Black Walnut Tree in your smoker increases your mite drop level. I have not yet tried this personally, as I had not heard it mentioned until after all our leaves were gone last fall.
Staghorn Sumac pods are claimed to do the same thing, but from personal experience, the pods work great for smoking hives but we have not seen a significant increase in the mite drop level after smoking them.
If you are interested in a chemical free mite management program, you might want to search the forums(using the search button at the top of the page), for Food Grade Mineral Oil(FGMO), and "Small Cell" beekeeping will be two subjects that have shown great promise in the fight for control of our hives from the Varroa Mite.