The staminate flowers opened early in Indiana the years of 1950, 1951, and 1952. The weather was more or less ideal during the time the catkins had elongated and about ready to shed pollen. This warm spell was followed by a fairly cool weather and considerable rain, which delayed the opening of the pistillate flowers, consequently the pollen dried and was lost before the pistil was receptive.
The few walnut trees in the University plantation have always had the best of care. The trees have been mulched, fertilized (both through root and leaf feedings), sprayed, cultivated and seeded to grass with the grass clipped. The trees are some distance away from other seedling walnuts and a bit off the beaten path of the right direction of the spring winds. The varieties are Ohio, Stambaugh, Stabler, Rohwer, and Thomas. When the spring weather is balmy at flowering time, the trees bear a respectable crop but let the weather change to cool and moist and then that is the time one begins to think about calling up the sawmill to see if there is any need for some good walnut logs.
MR. MAGILL: That's a mighty good discussion. I see Mr. Ward has been observing walnut trees closer than I assumed he had.
Mr. Chase, I know you have seen a lot of things in Tennessee that you are not going to tell us about, but I suggest that you discuss some of the things you have observed about walnut trees bearing anywhere.
MR. CHASE: Alternate bearing has been a problem with fruits and nuts since time immemorial. I know a tremendous amount of work has been done with the apple, which has a definite biennial bearing habit. There have been all sorts of things tried to make it bear annual crops, and as far as I know, there has not been anything effective developed along that line. Of course, there are varieties of apples that tend to bear annual crops.
As Mr. Ward brought out—he took all my thunder, so I don't have much to say—a tree may set a heavy crop of nuts one year because frost or poor pollination the year before destroyed the crop so that a large amount of carbohydrates were built up in the tree. Now, the tree in producing a heavy crop of well filled nuts utilizes every bit of carbohydrates it has stored and can manufacture. While it is doing this the terminal bud is being formed for next year's crop, and if there isn't a sufficient amount of carbohydrates in the tree at that critical period, there is not likely to be a flower bud formed.
This is not limited just to walnuts, but occurs with nearly all fruits and nuts, with the possible exception of the chestnut.
We made a study which was reported in the 1946 report by Mr. Zarger in which he reported the bearing habits of some 135 trees over a 10-year period, and there were definite bearing cycles, or bearing habits. It was not always an on year followed by an off year, but possibly two years in a row, then nothing. There were some trees that went three years without a crop, then a crop. Very few, however, had annual crops, and the annual crops were heavy or moderately heavy, followed by what we consider a light crop.
These trees were scattered through seven states and, of course, conditions were not the same. They were all seedling trees, but careful records were kept on the bearing habits. There was a group of trees that could not be classified into any definite bearing habit. In those instances we suspected unfavorable weather at pollination time, but as a general rule, in our section I don't believe we are concerned with that factor.
The Thomas, which we can watch carefully in a nearby orchard, is definitely on one year and off the next. Quite a few are on one year and off two years. We haven't found any way to make that an annual crop, because when it sets a crop, it sets a bumper crop, and there is simply not enough food in the tree to set a sufficient number of fruit buds for the following year's crop. I am sure that a lot of you folks have observed this, and I think, Mr. Magill, that you might sound out some of them.