HAZELS AND/OR FILBERTS
There is a certain amount of confusion in the minds of many people
regarding the difference between filberts and hazels, both of which
belong to the genus Corylus. Some think them identical and call them all
hazels dividing them only into European and American types. I see no
reason for doing this. "Filbert" is the name of one species of genus
Corylus just as "English walnut" is the commercial name of one of the
members of the Juglans family. There is as much difference between a
well-developed filbert and a common wild hazelnut as there is between a
cultivated English walnut and wild black walnut.
For ordinary purposes the nuts sold commercially, whether imported or
grown in this country, are called filberts while those nuts which may be
found growing prolifically in woodlands and pastures over almost the
whole United States but which are not to be found on the market are
called hazelnuts. This lack of commercialization of hazelnuts should be
recognized as due to the smallness of the nut and the thickness of its
shell rather than to its lacking flavor. Its flavor, which seldom varies
much regardless of size, shape or thickness of shell, is both rich and
nutty. The three main food components of the hazelnut, carbohydrate,
protein and oil, are balanced so well that they approach nearer than
most other nuts the ideal food make-up essential to man. The English
walnut contains much oil and protein while both chestnuts and acorns
consist largely of carbohydrates.
One salient feature which definitely separates the species Corylus
Americana or wild hazel, from others of its genus, is its resistance to
hazel blight, a native fungus disease of which it is the host.
Controversies may occur over the application of the names "hazel" and
"filbert" but there is no dispute about the effect of this infection on
members of genus Corylus imported from Europe. Although there is wide
variety in appearance and quality within each of the species, especially
among the European filberts, and although filberts may resemble hazels
sufficiently to confuse even a horticulturist, the action of this fungus
is so specific that it divides Corylus definitely into two species.
Corylus Americana and Corylus cornuta, through long association, have
become comparatively immune to its effects and quickly wall off infected
areas while filbert plants are soon killed by contact with it. Hybrids
between filberts and hazels will usually be found to retain some of the
resistance of the hazel parent.
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.
[Illustration: _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.
October 5 and 6: Picked all of hazilbert No. 2 except the last two
nuts.
Gellatly filberts were picked about October 10 and were ripe at
that time.
October 11 to 13: Two English walnuts were picked and found to be
as ripe as they would get. These as well as the black walnuts
showed distinct signs of lacking summer heat needed for their
proper development. The last two nuts on hazilbert No. 2 and the
only nut on hazilbert No. 4 were picked at this time and were ripe.
Chestnut burrs had opened up and the nuts enclosed were fully
mature.
October 19 and 20: I found the last of the Winkler hazelnuts had
been picked during the previous week, approximately October 14.
These were left the longest on the bush of any hazel and still were
not ripe although they were not entirely killed by the several
frosts occurring before that time. They are always much later than
the wild hazel."
On October 20, I had an opportunity of comparing the action of frost on
the leaves of these plants. Those of the White Aveline type had not
changed color and were very green. The leaves of the Jones hybrid showed
some coloration but nothing to compare with those of the Winkler hazel,
many of which had the most beautiful colors of any of the trees on the
farm--red, orange and yellow bronze. Hazilbert No. 1, which resembles a
wild hazel in appearance and habits of growth, had colored much earlier
in reaction to the frost and was as brightly tinted as the wild hazel
and Winkler plants except that, like the wild hazel, it had already lost
much of its foliage. Some of the wild hazels were entirely devoid of
leaves at this time. Hazilbert No. 5 showed the best color effects with
No. 4 second and No. 2 last.
The color of the leaves and the action of the frost on the plants during
the autumn is another thing, in my opinion, that helps to differentiate
between and to classify European filberts, American hazels and their
hybrids. My conclusion in regard to the effect of frost is that the
reaction of the Winkler hazel is very similar to that of the wild hazel
in color but exceeding it in beauty since its leaves do not drop as soon
after coloring. At this time, the leaves had not changed color on the
imported European plants, the Gellatly filberts from British Columbia or
the White Aveline type. They had turned only slightly on the Jones
hybrid. I think an accurate idea of the general hardiness of a plant is
indicated by the effect of frost and by early dropping of leaves, using
the sturdy wild hazel as the limit of hardiness and assuming that its
hardiness is shown by both degree of coloration and early dropping of
leaves.
In noting the action of frost on the Winkler hazel, I have mentioned
that it was more like that on the American hazel than on the European
filberts. The Winkler has always been considered a native woodland
hazel, but, although it does show several similarities to Corylus
Americana, I have also noticed certain qualities which definitely
suggest some filbert heritage. I have based my theory on a study of the
Winkler hazels which have been bearing annually at my farm for six
years, bearing more regularly, in fact, than even the wild hazels
growing nearby. My comparisons have been made with wild hazels in both
Minnesota and Wisconsin and with European filberts.
I found the first point of similarity with the filbert is in the
involucre covering the nut. In the wild hazel, this folds against itself
to one side of the nut, while in the filbert it is about balanced and if
not already exposing a large part of the end of the nut, is easily
opened. The involucre of the Winkler hazel is formed much more like that
of the filbert than that of the hazel. In Corylus Americana this
involucre is usually thick, tough and watery, while in the filbert it is
thinner and drier, so that while a person may be deceived in the size of
a hazelnut still in its husk, he can easily tell that of a filbert. This
is also true of the Winkler whose involucre is fairly thick but outlines
the form of the enclosed nut. Another feature about the involucre of the
Winkler which classes it with the filberts rather than the hazels is in
its appearance and texture, which is smooth and velvety while that of
the hazel is hairy and wrinkled.
The staminate blooms of the Winkler hazel show similarity to those of
both filberts and hazels. Sometimes they appear in formation at the ends
of branches, much as those of the European filberts do, in overlapping
groups of three or four. Again, they may be found at regular intervals
at the axis of leaf stems very much as in the case of the American
hazel. The buds on the Winkler hazel are dull red which is also true of
those on the hybrid hazilberts, another indication of hybridity.
The initial growth of the embryo nut is very slow in the Winkler as it
is in the filbert, as contrasted with the very rapid development of the
native hazel embryo which matures in this latitude about one month ahead
of the Winklers and some filberts. Although Winkler nuts are shaped like
hazels and have the typically thick shells of hazelnuts, their size is
more that of a filbert usually three times as large as a native hazel.
During the years between 1942 and 1945 many new hybrids between filberts
and hazels were produced. Four wild varieties of hazels, which had
unusual characteristics such as tremendous bearing and large size nuts
and others having very early maturing or very thin shelled nuts were
used as the female parents in making the crosses. Pollen was obtained
from other parts of the U. S. or from filbert bushes which were growing
on the place. Crosses included pollen of the Barcelona, Duchilly, Red
Aveline, White Aveline, Purple Aveline, the Italian Red, Daviana and
several hybrids between other filberts and hazels. By 1945 the number of
these plants were in the neighborhood of 2000 and by 1952 considerable
knowledge had been gained as to the hardiness, blight resistance to the
common hazel blight (known scientifically as cryptosporella anomala),
freedom from the curculio of the hazelnuts (commonly known as the hazel
weevil) and resistance to other insect pests. Also, considerable data
had been accumulated by cataloging over 650 trees each year for five
years; cataloging included varied and detailed studies of their growth,
bearing habits, ability to resist blight, curculio and other insects,
the size of the nut, the thinness of the shell and the flavor of the
kernel. Several books of all this detail were accumulated in trying to
nail down several commercial varieties that would be propagated from
this vast amount of material. Although some bushes produced good nuts at
the rate of as much as two tons to the acre, measured on the basis of
space that they took up in the test orchard, the most prolific kind
seemed to be the ones that had a tendency to revert to the wild hazel
type. The better and thinner-shelled types, more resembling the
filberts, seemed to be shy bearers so that there being a host of new
plants to catalog (more than 1000) which had not indicated their bearing
characteristics, we included these among the possible ideal plants we
were seeking. Although there were several plants that could be
considered commercial in the original group of over 650 it has been
thought that the waiting of a few more years to ascertain whether there
would be something better in the next 1000 plants to bear that would be
worthwhile waiting for and no attempt has been made to propagate the
earlier tested plants. Some of these 650 tested hybrids proved to have
nuts that were classed as Giants being much larger than the filberts
produced by male or pollen parent such as the Barcelona, Duchilly or
Daviana, and several times the size of the nuts of the female parent
which was the wild hazel.
[Illustration: _Wild Wisconsin Hazel discovered on Hazel Hills Farm near
River Falls. Note size of nuts in husks as compared to woman's hand.
This plant became the female parent in over 1,000 crosses by pollen
furnished from male blooms of Duchilly, Barcelona, Italian Red, White,
Red, and Purple Aveline and many other well known filberts. Photo by C.
Weschcke_]