Production: Size of crop in proportion to size of tree
Percentage of unfilled nuts: 1947 1948 1949 1950 R*H --------------------crop pounds
* R = 1/2 limb spread. * H = height; lowest branch to top.
In addition to these data, photographs, both in black and white, and in color, were taken of the trees and often of the surroundings, and a map made so that the trees can be located in the future by any one wishing to do so.
For examination by any one wishing to do so, there are on the secretary's desk copies of the case histories, as written up, of the first and second prize winners, the Duke and the Burson.
A careful study of these ten trees has not revealed any single factor that can be pointed to as essential to the production of a superior walnut variety. They were found on good and on poor soils, on good and poor sites, in soils of a wide range of pH values from very acid to alkaline in reaction. Most of the trees were located in the southern part of the state at 39° to 40° North Latitude, but it is hard to imagine that the latitude has any specific effect on the superior qualities of the nuts.
In all cases where the trees were now standing in impoverished soils, low in humus, fertility, and in pH value, it was quite evident that the soil was probably in far better condition when the trees got their start fifty to a hundred or more years ago.
In 1947 scions of six of these prize winning trees were successfully grafted into established ten year old black walnut seedling trees at the Mahoning County Experiment Farm at Canfield, Ohio, location 41° north latitude. The scions grew nicely in 1947 but all were winter killed during the winter of 1947-1948 with the exception of one scion of Kuhn and one of Davidson. Two scions of Duke, two of Kuhn, one of Athens, one of Orth, seven of Jackson perished during the first winter after grafting. This severe killing of 1947-48 apparently indicates that winter injury to these varieties may be expected some years when they are planted under conditions similar to those at the Mahoning County Experiment Farm. The one scion of the Davidson variety came through in fine shape, so this would be the exception.
The winter of 1947-48 was unusual in the severity of the winter injury to the black walnut trees at the Mahoning County Experiment Farm. Two ten year old Stabler trees and a ten year old Jansen tree killed back to the ground level, and one year old growth of Cowle, Havice, Jansen, Murphy, Mohican, Ohio, Stambaugh, Twin Lakes, and Lisbon was badly damaged although not always completely killed.