hickory leaf mystery

[bluthum]

I noticed yesterday while on my evening hike there were a lot of hickory leaves newly fallen.  The complete leaf was on the ground and the end of each just back of the node was brown and a little ragged. Didn't appear to be chewed off, more like they were just weakened and broke off. The leaflets were still green so they had been nourished right up to falling down.  About an inch up the leaf stem from the separation there is a little swelling in the stem inside of which is a tiny brown  structure that doesn't look    insect  related, more like a viral growth but it's hard to make out at 20x.  

I very much doubt this to be a health threat to the black hickory population but I'm curious if anyone can tell me what it is. Strange thing is how the leaves all came down on the same day or so and we are talking thousands of leaves although no where near a noticeable amount per individual tree. 

[Don P]

Just a guess.
Phylloxera caryaecaulis - Bugwoodwiki

[Tacotodd]

@Don P that sounds like a very good candidate for what @bluthum is describing.

[bluthum]

Yeah Phylloxera does sound very close at least.  Reading the description given I'd say that is most likely the correct genus maybe even species. I think the mystery is solved. Thanks!

Never saw the bugwood wiki before, that's a great source.

One of the oddest things about the event is how the leaf happened all on about the same day on trees spread over many acres. I'll gather up a few of the fallen leaves today and keep around to see how the galls develop. 

[KEC]

How about a photo or two?

[bluthum]

I've tried a few pics but they are not descriptive much with the tools on hand.  Imagine a perfectly normal hickory leaf except the very last end of the leaf stem is brown and raggedy. Like 3mm of brown and ragged.

The swelling right up the stem [gall?] wasn't noted on some leaves I picked up today.  It's supposed to rain for a couple days so the leaves on the ground will minimally dry up soon hence the investigation will continue for a little while.