MR. McDANIEL: I had the bunch growth developed on a new species this year in my planting in north Alabama, a 12-year-old tree of ~Juglans rupestris~. It is a growth that looks practically the same as the bunch disease on the Japanese walnut. I believe that's the first time it's been observed on that species. There are no butternuts or Japanese walnuts on the farm. There are dozens of black walnuts (seedlings and several varieties) none of which show the bunch symptoms. However, it is typically developed on some Japanese trees a few miles away.
At Whiteville, Tenn., Dr. Aubrey Richards has a suspicious looking tree among some two year old seedlings of ~Juglans major~ from Arizona seeds.
MR. CHASE: I'd like to add to that, too, Mac. In our walnut arboretum we had some ~rupestris~, and I had been suspicious of its being diseased for a number of years. I finally have decided that it had the bunch disease, and those trees down at Norris have all passed out.
MR. McDANIEL: My tree came from Norris, 10 years ago.
DR. MacDANIELS: ~Juglans rupestris~ killed by the disease.
MR. STOKE: Just because this is a little contradictory to what you have heard, I want to say that my experience has been this: I have an old nursery—well, there is a butternut in the row and also heartnut—Japs. One of those Japs has had the bunch disease for six or eight years. None of the others has been affected. It was a variety I wanted to perpetuate. I took an apparently healthy scion from that and put it on another tree, and that grafted tree also had the disease. But there has been no evidence of contagion from this Jap to the other Japanese, butternuts and black walnut in the same planting in the immediate neighborhood—in fact, they crowd each other. That's a statement of fact.
I spoke a little while ago of an old black walnut tree that had that disease for a number of years and none other in that planting had it.
MR. O'ROURKE: Is there any correlation between the age of the tree and the expression of the disease?
DR. McKAY: It's been our observation that we haven't had it in our nursery to any extent. We have seen it in the nursery of J. Russell Smith on Persian walnut. It, to my knowledge, is the only place where we have seen it on nursery trees. It may be that our nursery happened to be free of the inoculum, because it's been about a mile from the orchards.
MR. O'ROURKE: Would you by any chance think it might be seed borne?