In my section our latest spring frost averages the 20th of April, and yet I have several varieties that do not bloom until after the first of May. That's the ideal condition.
DR. MCKAY: That's true, Mr. Stoke, but here is another point to consider. Persian walnuts have a short cold requirement, you know that. Hence, in February or early March or any time, even in January, when we have a warm spell of a week or ten days or even shorter, sap will rise in the trees, and they will start to grow.
MR. STOKE: Not all. In plants of some varieties new growth will hardly start.
DR. MCKAY: Perhaps you may have varieties that will not start, but the tendency is to start.
MR. STOKE: If you have one with that early tendency, cut it out.
DR. MCKAY: I'd like to get back to this opinion here on the question of frozen ground, dormant roots and the effect it has on the top of the tree. Now, how about our academicians over here, Dr. MacDaniels or Dr. Crane. Let's hear from one of you.
DR. MACDANIELS: It is my opinion that with a walnut tree of good size the frozen ground would have little or no effect on the buds starting growth. The twigs and the trunk would warm up to the temperature of the air, and when that happens growth occurs. Water is available from that in the trunk and the deeper roots. This would happen regardless of how the surface roots were treated.
DR. MACDANIEL: Or whether the tree had any roots on at the time.
DR. MACDANIELS: The best solution to the frost damage problem is to find trees which vegetate late enough to avoid the spring frosts. Somewhere on this terrestrial globe there must be some, because I remember years ago J. F. Jones sent out some Persian walnuts of Chinese origin. I planted three, and they did not start any growth until about the first of July, and they were still growing strong when frost hit them in the fall. Now, somewhere in between these extremes, somewhere in the climatic analogue of our region we will find Persian walnuts which will have a delayed vegetating period, and that will be the final answer. At least, I think so.
DR. MACDANIEL: I'd like to ask a question. In F-2 hybrid walnuts do you find much segregation of those for later initiation of vegetation?