The ideal nut of genus Corylus should combine qualities of both hazels and filberts. Such a hybrid should have the bushy characteristics of the American hazel with its blight-resisting properties and its ability to reproduce itself by stolons or sucker-growth. It should bear fruit having the size, general shape, cracking qualities and good flavor of the filbert as popularly known. The hybrids I am growing at my farm, which I call "hazilberts" and which are discussed later, seem to fulfill these requirements. The plants may be grown as bushes or small trees. They are blight-resistant and their nuts are like filberts in appearance. Three varieties of these hazilberts have ivory-colored kernels which are practically free of pellicle or fibre. They have a good flavor.
A comparison of the ripening habits and the effect of frost on the various members of the genus Corylus growing in my nursery in the fall of 1940, is shown by these extracts taken from daily records of the work done there. It should be noted that the summer season that year was rainy and not as hot as usual, so that most nuts ripened two to three weeks later than they normally do.
"September 7 and 8: Wild hazels ripe and picked at this time. (Their kernels showed no shrinkage by October 25.)
September 14 and 15: I picked ripe nuts from hazilbert No. 5 which seems to be the first to ripen. Also picked half of the European filberts. (There was slight shrinkage in the kernels of the latter a few weeks later showing that they could have stayed on the trees another week to advantage.)
All of the nuts of a Jones hybrid, which is a cross between Rush and some European variety such as Italian Red, could have been picked as they were ripe. Some were picked.
The almond-shaped filbert classified as the White Aveline type, was not quite ripe; neither were hazilberts No. 2 and No. 4, nor the Gellatly filberts. Wild hazelnuts at this time had dry husks and were falling off the bushes or being cut down by mice.
September 21 and 22: The remaining European filberts of the imported plants were picked. Also, I picked half of the White Aveline type nuts.
Carlola Hazilberts No. 5, about 8/10/42. This is the earliest ripening and thinnest shell of the large type hazilberts, not the largest size however. Carlola Weschcke shown in picture. Photo by C. Weschcke
September 28 and 29: We picked most of the nuts remaining on hazilbert No. 5 and the remainder of the White Aveline type. At this time we record a heavy frost which occurred during the previous week, that is, between September 22 and 28th. Since it froze water it was considered a "killing" frost. However, the damage was spotty all over the orchard, most things continuing to develop and ripen. Winkler hazels picked and examined at this time showed them far from ripe. Hazilberts growing next to limestone walls on the south side showed no signs of frost damage whereas the Winkler, on higher ground, showed severe damage to the leaves and the husks of the nuts which immediately started to turn brown. Leaves of other filbert plants in the vicinity showed no frost damage and the very few nuts that had been left on, such as those of the Jones hybrid, were undamaged.