In examining the nuts, emphasis was placed on size and color of the nut, the large, bright brown nuts being considered more desirable than the smaller, duller colored, pubescent nuts. The amount of space between the shell and the kernel was important. If the kernel fitted tightly it was easily broken or chipped in cracking the nut. Thickness of shell was of minor importance as only a few were thick enough to make cracking difficult.
The kernel characters were of most importance since the kernel is the reason for producing the nut. The kernel must be plump, smooth, light brown in color, and free of the superfluous pellicle, or fibrous material that is characteristic of the Barcelona kernels. Generally, seedlings with Rush as one parent had very little of this superfluous fibrous material and the best of them were much superior to Barcelona in appearance and dessert quality. Flavor received less consideration since most of the seedlings were reasonably good in that respect.
Given a good kernel, and there were many of them, it became necessary to rely upon other characteristics to eliminate the less desirable of these seedlings. It was here that the records of yields and catkin hardiness were valuable. After several years it became evident that certain seedlings were consistently high yielding while others were low yielding. Hardiness of catkin also varied greatly and rather consistently from year to year. Weather conditions influenced catkin killing greatly. Catkin hardiness is important since the pollen is necessary for nut production and must be present in abundance as its movement in the orchard is subject to the vagaries of the wind, and only a small percentage of that in the air ever comes in contact with the stigmas of the other varieties.
It is the purpose of this paper to indicate the value, insofar as it may be estimated from the available data, of the different varietal crosses in obtaining desirable filbert hybrids. Table 1 contains a list of crosses made, the number of seedlings raised, and the percentage of these which were of sufficient merit to be retained for further study. The percentage of seedlings propagated indicates even more definitely which crosses are of the greatest value in producing superior seedlings as only the outstanding seedlings were propagated for a second test. Selections included in Table 1 are there by virtue of their all-around merit.