by Sandy Garland / FWG
Several years ago, we noticed an odd phenomenon in the middle of a field that had pretty much been taken over by dog-strangling vine (DSV). A circle of mostly grass, about 4-5 feet in diameter had no DSV growing in it. I mentioned our “crop circle” to colleagues at the garden and one speculated that a walnut tree had been growing there and its roots were producing something that was inhibiting DSV.
This made sense, but then the circle grew and grew until this year, it’s a good 30 feet in diameter! If residual tree chemicals had created the circle, you would expect less effect as time went on. Nothing growing in the circle seemed to explain the lack of DSV – meadow foxtail grass and another common species, both of which grow abundantly at the FWG.
This year, I was amazed to find several more “crop circles” – this time in relatively shady areas. Two are on the north side of the woods (see photo at left) and one is along the first part of the Bill Holland Trail under sumacs (photo below). They’re all about 5 or 6 feet in diameter. Coincidentally, all three contain a small amount of virginia creeper, although virginia creeper is also growing happily among thick stands of DSV.
For me at least, this has become a true mystery. And I would love to solve it as it may provide some clues to keeping DSV under control. Meanwhile, we’ll keep an eye on those circles and hope they grow like the first one did.