There's a Black Walnut Tree over behind our backyard fence. I think it's on our land, though. Basically, not all that far away, I planted a dormant Shumard Oak Tree this winter (maybe 7' or so tall, roughly 1.5 - 2" caliper). It was my understanding oaks are pretty resistant to juglone, which the Black Walnut produces. I tend not to think about the Black Walnut because it's part of a line of wild trees running along a creek that's the rear border of our 'edge of town' lot.

So last night, thinking about how many plants are impacted by juglone, such as silver maple even though red & sugar maple are said to be okay, I got to checking up on shumark oaks. Thing is, Googling 'Juglone Shumard Oak' or something like that tends to pull up a bunch of web pages talking about both kinds of trees.

And get this; while Shumard Oak is in the Red Oak group, and Scarlet Oak is related to Shumard Oak per my 'Native Trees for North American Landscapes' book (which I love), I see online that Northern Red Oak is resistant to Juglone, but Scarlet Oak is vulnerable to it.

So, got a couple of questions.

1.) What impact, if any, is the proximity of a Black Walnut Tree likely to have on a Shumard Oak Tree?

2.) If the Black Walnut is a problem, and, well, to be blunt, we kill it, how long a time frame would we be looking at before the juglone issue would fade away?

Richard.