Not sure why some have turned yellow when others are still looking pretty good. I dug most of those seed bed roots within a couple miles of my house with the exception of the ones I got from Billy. Some of Billy's roots the tops have yellowed and others are still green.
But that is about what I found in the woods today too. Several, mostly younger plants were yellow and some almost down and out, where some larger more mature plants were still doing well.
The hollow that I dug in today, I have dug it no telling how many times... I only harvest older 3 prongs or 4's (only found 1 four in that hollow ever) and leave the smaller 3's.. and I only hunt it every 3 years or so.
And every time I dig there, I always come out with some nice older roots.
I think the deer just browse so many of them, that by the time seng season opens about half of them no longer have a top. That explains part of why I just keep bringing older roots out of that hollow even though I have dug it a dozen times of more (over the years).