Black Walnut v Blueberry and Rhubarb, Round 2

It's time for another walk through BlackWalnutVille.

At least, that's what I've decided to call that zone I live in which makes in-ground planting rather difficult.  Basically, black walnut is toxic to quite a few yummy fruits and vegetables due to a chemical throughout the entire tree called juglone. 

Two of the plants effected by black walnut toxicity are blueberry and rhubarb.  

I discovered the rhubarb problem last growing season after I discovered rhubarb beginning to grow in the wild area of the backyard... which quickly died after a couple of weeks.

Later, I planted blueberries, one on either side of the treacherous trail.  Those died, as well.  Of course, that was entirely my fault.  I had forgotten that blueberries were sensitive to the juglone in black walnut.

Oops.

It appears, however, that the loss of those plants may not have been entirely due to the black walnut's toxicity.  I mean, yes... it was a factor.  I don't believe that it was the entire cause, anymore, though.


Why is that, you ask?

Because the rhubarb has re-sprouted this season, and it's growing at a nice pace.  It's twice as large as it was last year when it died its horrible death.

Not only that, but one of the blueberry bushes is attempting to grow back.

Of course, the other blueberry bush is still looking pretty shabby, but one out of two isn't so bad, right?


As I look at these plants, I think that it's pretty safe to say that planting any of them in this yard was a very bad idea, but location is perhaps the most important factor.

You see, distance from the black walnut tree is a major factor in toxicity, specifically with large black walnuts, which are what we have growing here.  The reason why I mention distance in this case is that the rhubarb is closest to the base of the black walnut, and is also the healthiest of the three.

Why would that one be healthiest?

Because there isn't nearly as much juglone in the soil at the base of the tree as there is at the outer edges.  This is because you don't have the same invasion of roots.  The roots ate the base are mature: they don't have the same need to secrete the phytotoxin.

Naturally, the black walnut sensitive plant that's showing the most damage is the blueberry plant that's farthest away from the tree's base... and it looks really, really bad.

Big difference there, right?

The thing is, though, that none of the plants are actually thriving.  The rhubarb's stems, which are the important parts, are pretty thin.  And the blueberry?

Ugh.  It just looks... weak. 

It's growing, but I don't expect much from it.  Perhaps a couple of berries, but I don't expect a large harvest out of the plant.

I mentioned though, that while black walnut was a factor, I don't think it was entirely the cause of last year's problems.

I think the other half of the problem was the climate.  Last year was hot and dry - for Minnesota, that is.  This time last year, the temperatures were in the 80s and 90s.

This year I'm ecstatic if the temperatures are in the 60s... 

And it's extraordinarily wet.  I don't think we've had a totally rain-free day all week.

So it was a combination of factors, rather than only the fault of the black walnut.  I wonder if they'll survive until harvest this season, or if they'll succumb to black walnut toxicity again.

Hmmm...