(See Appendix.)
The fact that this Cryptosporella is related to the black knot of the plum is an interesting feature; and that it attacks the growing canes during the growing season and fruit during the fall and winter. He suggests the treatment of removing all the infected branches during the fall and winter. I would add to that, complete eradication of all diseased branches of the host, and they are rather easily seen, in the fall as soon as the leaves are off—then a thorough spraying with strong Bordeaux mixture, at least 5-5-50, preferably stronger than that, of course burning all the material that you cut out. One is at a disadvantage if there are wild hazelnuts in the neighborhood. How to handle that problem I am hardly prepared to state; perhaps, by eradication of the wild hazelnut in the vicinity.
The Secretary: I think that would be impossible in most regions.
Professor Waite: Mr. Kerr had his growing on the eastern shore on an island where there are no wild hazelnuts and they were not attacked by the fungus.
A Member: They are all dead now.
Professor Waite: The number of sprayings during a season is an undetermined question. It will be necessary, probably, to spray two or three times. You can certainly protect the two-year wood in that way by making a fall spraying and a spring spraying. This will keep them thoroughly covered with Bordeaux mixture but whether or not three or four sprayings are necessary remains to be tested.
The Chairman: Are any varieties of European hazels immune?
Professor Waite: I have not studied them enough to answer that question. I don't know. They all seem to go down. Perhaps Dr. Deming can answer.
The Secretary: I don't know.
Professor Waite: I think that is all I want to say, except one thing, and that is about the physiological aspect of these, diseases. I touched upon that phase in discussing the matter of environment in the introduction of foreigners to places where they are not adapted. In some particular seasons and circumstances even the native trees suffer. One type of injury which has caused great trouble with the English walnuts and pecans, and also with apple trees and has also caused trouble with our native red oaks, is freezing when the trees are in a non-resistant condition. There is an example of this within three minutes' walk of this building. Here are the climatic and temperature conditions that bring about disaster, particularly if preceded by a dry season. Let us start with a dry season. The season of 1911 was conspicuously dry in this locality and the adjacent states of Virginia, West Virginia and Maryland, but about the first of September the rains came. Up to that time even the native forest trees such as oaks and chestnuts showed the stress of lack of moisture very seriously and were somewhat yellow and pale looking, mainly from water and nitrogen starvation. When the rains came the wilted trees all greened up, every tree in the parks brightened up, and we had fine growing conditions until October and no cold weather up to New Year's. It was warm that fall and even on New Year's day the warmth was noticeable. On the 12th of January we had the record cold temperature for this locality in the history of the weather bureau, except one year. We had fifteen or seventeen below zero and it was as low as thirty-eight in low spots in the Potomac Valley in West Virginia. Those trees had never been fully shocked into winter conditions. The cambium growth and sap flow had not been stopped and the physiological changes needed to get the trees ready for cold weather had never occurred. They were not ready, not only as to the bark, but in the trunk and wood. The result was that the trees were seriously injured, the less matured twigs died back, and the trees were frozen on the trunks down to the ground line. In the freeze of 1904 in New York I was surprised to find that the peach trees were not all killed. They were frozen through and through and yet the trees did not die. The question of winter injury hinges not alone on low temperature, but it also depends on the condition which the tree has reached when the cold strikes it. Now, to tell you still further about what that cold wave did, I will ask you to look at that row of red oaks near the Smithsonian which I just alluded to and see the big ribs of dead bark where the cambium layer has been shocked, and checked in other places. You will find these trees ribbed and ridged to about half way down the row. Those trees are subject to special disadvantages; they lack subsoil drainage and they have an excess of manure draining down through the paving stones. They have an excess of nitrogen and lack of drainage. The subsoil is a heavy clay. That brings up another thing that I want you to notice in regard to winter injury. Plant not only hardy varieties, but select localities with good subsoil drainage. The walnuts and hickories, belonging to the two great families of juglans, and the oaks and chestnuts, want good subsoil drainage. Where the underlying rocks are vertical the conditions are ideal. They do not like a heavy clay subsoil, but do best where water and excess nitrogen can get away.