by Sandy Garland
Once upon a time, 4-5 years ago, I pulled out the DSV that was growing under this walnut tree. I put down some newspapers to keep it from growing back (we’ve learned subsequently that this doesn’t really work) and forgot about it. This year, I noticed there is almost no DSV under this tree. The few DSV plants there are small and wilted.
Another walnut tree, about the same age as the previous one, but this one has been ignored and is surrounded by DSV. A new volunteer has undertaken the job of pulling out this DSV in hopes of duplicating the experience just described, i.e., hoping the tree will inhibit regrowth of DSV.
Another walnut tree, this one is about 20 years old, certainly old enough to be producing nuts.
Under it, inside the “drip line,” there is no DSV and, in fact some bare spots where nothing is growing.
Outside the drip line, there are patches of grass with no DSV, but the pattern is irregular.
A closer look at a DSV-free area next to the large walnut tree. In this one, you can see that the green taller vegetation is DSV.
An area that was sprayed with Roundup last summer and again this spring. DSV is yellow and wilted, but most other vegetation has also been killed.
Looking in the opposite direction from the previous photo, this large walnut tree has successfully defeated DSV (except for that patch at the right of the trunk) and grass is growing under the tree.
Is this a relationship or just a lot of coincidences? Time to investigate it with some controlled experiments. Anyone interested?