know. I was fortunate in securing for the 1919 contest enough specimens
of the greater portion of those hickories which have been propagated
experimentally to a considerable extent so that some information on this
point can be given. The printed slip which I will pass around gives the
results of these tests and will give a better idea of the different nuts
than can be done in any way except by passing around samples. It will be
noted from the slip that the nuts run very close indeed and it is very
probable that another year these nuts would not show exactly the same
results for it has been clearly shown that nuts vary greatly from year
to year. There are other characteristics of hickory nuts which are of
great importance which are not shown in the annual contests. These are
the bearing records of the tree, its ability to stand various diseases
and most of all how it will work out when grown in orchard form. This
can only be told by experience. From the fact that, in the 1919 contest,
of the ten varieties of the experimentally propagated hickories there
was only a difference of five points between the highest and the lowest,
it shows that the merit of each nut is sufficient so that all of these
should be tested out in orchard form. In other words we should not for
example select the Vest and Manahan as the best that we have and
propagate them to the exclusion of the others. It is probable that there
will be great differences in the orchard behavior of these various
hickories shown as this is done and that then we shall be able to select
the most desirable varieties. Some tests made recently on nine standard
southern pecans the Schley, Burkett, Moore, Alley, Delmas, Moneymaker,
Pabst, Stuart and Vandeman show a great difference between the highest
and lowest in the number of points awarded, this difference being 10
points as against 5 in the cast of the hickories. The Hatch bitternut
and Stanley shellbark noted on this slip are here not because it is
believed that, as market nuts, they will compare with the first ten
mentioned but because they are the best nuts we now have which are not
shagbarks or of which the shagbark is not one parent. It is believed
that those nuts will be valuable for hybridizing purposes.
There is one matter suggested by the slip on which I will touch although
it is not properly within the scope of the subject set for this paper
and that is the possibilities of hickory breeding. Of the ten hickories
noted on the slip as receiving 70 to 75 points, four, it is agreed, are
hybrids. The examination which I have made of the others leads me to
believe that more of them are, but four out of ten with the possibility
of more is sufficient to cause us to take notice. There are some nine
hickory species native in the north eastern United States and they
hybridize to a considerable extent. Some of these species show most
remarkable differences in characteristics. The shagbark is unexcelled
for quality of kernel. The shellbark bears nuts as large as the largest
black walnut. The bitternut bears nuts with a thinner shell than any of
the finest southern pecans and with a larger proportion of kernel. What
we know about practical plant hybridization leads us to believe that we
can combine the good qualities of these various species of hickories.
Think of what it would mean to have hickories equal in quality of kernel
to the best shagbark, of the size of the largest black walnut with a
shell thinner than the thinnest shelled pecan we have even seen, and
with a larger proportion of kernel.
While the hickory is the nut which has given as the most trouble in
propagation and gives us the most trouble in transplanting and grows the
slowest, it is certainly difficult to find one which gives more promise
either in growing the fine hickories we now have or in breeding up
better ones. I am convinced that as soon as we can furnish the fine
hickories we now have in commercial quantities they will command prices
equal to those paid for the finest pecans.
* * * * *
THE PRESIDENT: I will call upon Mr. J. F. Jones, of Lancaster,
Pennsylvania, who has the subject of "Selecting and Handling Scions."
SELECTING AND HANDLING SCIONS
J. F. JONES, NUT SPECIALIST, LANCASTER, PENNSYLVANIA
In the selection of scions of nut trees for grafting the propagator
should keep in mind the fact that the wood selected must be full of
vitality and must be of solid, well matured growth, that will stand the
maximum amount of exposure and hardship after being grafted, as the
grafts and stocks of nut trees callous or heal very slowly in comparison
to fruit trees, and the scions must be of solid, well matured growth if
good results are to be obtained. These requirements usually go together
however and if we select scions of solid, well matured growth, we
usually get scions in which the tree has stored the maximum amount of
"starch" or vitality.
HOW TO JUDGE SCIONS
The experienced propagator of nut trees can quickly distinguish between
good and poor scions for grafting, but the beginner, not knowing the ear
marks of good scions, often fails to select the best scions for
grafting. The common mistake made by the beginner in the selection of
scions of nut trees, is in selecting the smaller growth. The smaller
growth is usually more pithy and lacking in vitality and gives poor
results in grafting. Poor scions are usually characterized by pithy wood
and a light colored, thin bark. The buds are usually farther apart than
they are on good scion wood, though this is not always true, as good
scions sometimes have the buds set well apart, except near the
terminals. The distinguishing marks of good scions are solid, well
matured growth, and a thick, dark colored bark. The buds are also larger
and usually set closer together.
WHEN TO CUT SCIONS
Scions must be cut while the tree is still dormant and, in the case of
trees that the wounds bleed when the tree is cut, as do the English and
Japan walnuts, under certain conditions, we must guard against cutting
scions soon after severe freezing weather and before the tree has fully
recuperated. This semi-sappy condition of the trees following low
temperatures that freeze the wood, seems to be a provision of nature to
restore the moisture or sap lost from evaporation, and although more
noticeable in some species of trees, notably the English walnut, this
condition undoubtedly exists in other species of trees to a greater or
less extent and we always try to avoid cutting scions of any kind soon
after hard, freezing weather. I have found scions of the English and
Japan walnuts, cut from trees in this condition, to be practically
worthless for propagation, although the scions may have been cut in late
winter, long before the sap gets up in the tree, naturally.
HANDLING AND KEEPING SCIONS
Scions of nut trees for grafting should be handled carefully to avoid
rubbing off the buds, although this is not so important with nut trees
as with fruit trees, for the reason that the more important nut trees
such as the various walnuts, pecan and hickories have compound buds and
if the larger buds should be destroyed the secondary buds may be counted
upon to grow. The scions should be tied in bunches of a convenient size
to handle and, after being well tied and carefully labeled, should be
packed in paper lined boxes that will prevent evaporation of moisture in
the parking material. Any material that will absorb and hold moisture
and that will not heat when bulked, will answer the purpose for packing
scions, but we have found sphagnum moss to be the best material for this
purpose. This material can be obtained from the local florists or
dealers in cut flowers usually. Sphagnum will absorb a good deal of
moisture without actually becoming wet and will also hold this moisture
and give it off more slowly than any other packing material with which I
am familiar. This is especially important in keeping scions of nut trees
in good condition for grafting, because, if packed too damp, the scions
are soon spoiled for grafting, even if kept at a low temperature.
As a precaution against fungi, we usually use bordeaux mixture, two
thirds standard strength, to dampen moss for packing scions, especially
if they are to remain in storage several months.
Our rule is to use moss only slightly damp to the touch and if used in
sufficient quantity, say two or three times as much bulk as we have of
scions, we find no trouble in keeping scions in perfect condition for
months. In fact, as an experiment, we have carried pecan scions in cold
storage and without re-packing for fifteen months and then get a fair
stand of grafts to grow.
We usually advise putting scions in cold storage where convenient,
especially if they are for use in late May or June, but this is not at
all necessary if the scions are packed in moss only slightly damp. In
fact scions kept in an ordinary cellar at a temperature around 50
degrees have given us better results on the average the past two years
than have those from cold storage.
* * * * *
The association adjourned until 2 p. m.
AFTERNOON SESSION, FRIDAY, OCTOBER 8, 1920, 2 P. M.
THE PRESIDENT: We very fortunately have with us a gentleman from the
Bureau of Entomology, Mr. F. E. Brooks, who will talk to us about nut
insects for a time and we will be very glad to listen to him.
MR. BROOKS: I believe your program is full for this afternoon and I
shall keep you but a few minutes.
A little more than a year ago the problem of insects affecting the nut
crop of Northern United States was assigned to me by the Bureau of
Entomology. I wish to say the work has been very delightful to me from
several standpoints. In the first place, it has brought me into
association with a delightful group of workers. I want to express to you
the pleasure I have had in meeting the various nut growers of the
northern part of this country and noting the hearty way in which they
are ready to co-operate in solving the nut insect problems. The field of
work is interesting because there appear to be in sight no insect pests
that promise to embarrass or overwhelm the nut grower. We have a few
quite serious insect problems, perhaps none more serious than that
occasioned by our old acquaintance, the "chestnut worm." That problem,
however, is being solved rapidly in many localities by the chestnut
blight.
Thus far in the work, I have devoted most of my time to a study of the
species attacking the fruit of nut trees, and I may mention three groups
that have been given special consideration. First, the group to which
the chestnut worm, or chestnut weevil, belongs. There are two very
similar species of these weevils which attack chestnuts, one which
attacks hickory nuts and pecans, one which attacks hazel nuts and
numerous species which attack acorns. The adults of these weevils are
medium-sized beetles, yellow, brown or gray in color, and all have
enormously long snouts. The mouth is located at the point of the snout
and the beetles use these snouts to bore through the covering of the
nuts after the kernel is partially or fully formed. When the puncture
into the nut is completed one or more eggs are inserted by means of an
extensile, thread-like tube, or ovipositor, of the same length as the
snout. The eggs hatch into the familiar worms found in ripe chestnuts,
hickory-nuts and hazel nuts. The large hole in the shell of the nut is
made by the full grown worm as it escapes to enter the ground, where it
completes its transformation into a beetle. An interesting thing in
connection with these weevils is that each species confine its attacks
to one particular kind of nut. Even those species that attack acorns
show a decided tendency to distinguish between oak species and confine
themselves as groups very largely to particular species or botanical
groups of oaks. There is, therefore, no danger that any of these weevils
will multiply, for example in an oak forest, and then migrate into
nearby plantations of chestnut, hickory or hazel. Hazels might be used
for interplanting among chestnut or hickory trees with no danger that
the hazel nuts would become infested by the weevils that develop in the
chestnuts or hickory nuts. This habit of the weevils is greatly to the
advantage of the person who would plant a particular kind of nut outside
its natural range, or at a considerable distance from any other trees of
its kind. He could do so with reasonable assurance that the weevil
attacking his species of nut would not occur upon his trees until
brought into the locality by artificial means.
There is another group of weevils, nearly related to the common plum
curculio, the species of which attack immature nuts. In this group the
snout is much shorter than in the group just described, and the insects
are considerably smaller. There is one species, _Conotrachelus
juglandis_, that confines its attacks to the young fruits and shoots of
walnuts of the butternut group, another, _Conotrachelus retentus_, that
seems to attack exclusively the black walnut fruits from the time they
set until they are half grown, still another, _Conotrachelus affinis_,
that appears to attack only half-grown hickory nuts. Another species,
_Conotrachelus aratus_, feeds abundantly in some localities within the
leaf petioles of hickory. At least two other species of the group
commonly attack acorns. Those injuring walnuts lay their eggs on the
concave side of crescent-shaped punctures which they eat in the husks of
the young nuts. The larvae developing from the eggs cause the nuts to
drop within a few weeks and the larvae enter the ground to complete
their transformation. There is a divided tendency with some of these
species to attack the young wood and leaf stems of the introduced
species of walnut. Dr. Morris states that he has had young Japanese
walnut trees killed by _C. juglandis_ feeding in the grub stage within
the branches. He has, however, found that the pest succumbs to an
arsenate of lead spray.
Species of this group are apt to have alternating periods of increase
and decrease and a year of great abundance may be followed by a year of
comparative scarcity. This variation is due, at least in part, to the
fact that the larvae, as they feed within the tissues of their host
plants, often become rather heavily parasitized by certain two-winged
and four-winged flies, the parasitized larvae dying before they reach
the adult stage. Nature in this way does considerable toward holding the
pests in check, but artificial means of control will often need to be
considered.
The third group referred to is represented by a two-winged fly, about
the size of the common house fly, known technically as _Rhagoletis
suavis_, and commonly as the walnut husk-maggot. The fly is light brown
in color, with broad, irregular, dark brown bands on the wings. It
appears when walnuts are nearly grown and deposits clusters of small,
white eggs within punctures in the husks. Maggots hatch from the eggs
and at the time the walnuts drop these maggots are often found
converting the inner parts of the husk into a blackened, pulpy mass.
Infested nuts are disagreeable to handle and the husk does not part
readily from the shell. I have found the fly attacking black walnuts,
butternuts, Persian walnuts and Japanese walnuts, within the states of
West Virginia, Maryland, Pennsylvania, Ohio, New York, Connecticut and
Massachusetts. It probably occurs over the natural range of the black
walnut and butternut. It is proving to be a rather serious pest,
especially of the Persian walnut. Some of the infested walnuts appear to
drop prematurely and others adhere to the branches beyond the regular
harvest time. The shell of infested Persian walnuts parts poorly from
the husk and the nut is discolored, soiled and unmarketable.
The fly has rather interesting habits. I found that by pricking a nearly
mature black walnut with a pin, the wounds would almost invariably be
used in a little while by the female flies for depositing their eggs. In
one such wound, 180 eggs were laid within 24 hours. When the husk was
pricked a slight flow of juice would take place and the male flies would
soon find the spot, and, recognizing, I suppose, a suitable place for
the females to come to oviposit, they would stand guard at the puncture
awaiting the coming of the female. On one occasion I made minute
punctures in the husk of eight black walnuts and in a little while a
male fly was located at each puncture. Pairing took place usually as
soon as the female came and began to lay eggs. Sometimes a male would be
found at a puncture in the early morning and would hold its position
against all coming males throughout the entire day. When another male
would come to the nut the two flies would rear up facing each other and
engage in a brief sparring bout with their front legs. Usually, the
original occupant of the nut would be the victor. In some experimental
spraying of Persian walnut trees in Maryland and Pennsylvania the past
season with a sweetened arsenate of lead spray apparently good results
were obtained. In one case it seemed that the spraying was about 75 per
cent efficient in controlling the pest. In in another case, whereas last
year 75 nuts in 100 were infested, this year, after spraying only four
nuts in 100 contained the maggots at harvest time.
I desire to state to the nut growers that I am interested in any nut
insect problems that you may encounter and shall always be glad to
receive reports and specimens. Your co-operation in this work is greatly
appreciated and I hope we may continue to work together and that before
long we may have more definite knowledge of the means of preventing, to
some extent at least, the various forms of injury by insects to the nut
crop.
* * * * *
MR. RUSH: I cannot help but express a word of gratitude and appreciation
to my friend Mr. Brooks in helping me out of a serious difficulty that I
had in connection with walnut culture at Lancaster. A year ago I was
ready to throw up the sponge. In fact I might say that my whole crop
last year was destroyed by this husk-maggot. This year I have a very
fine crop. Last year it was practically worthless. This year I have very
few walnuts that were affected by the maggots, largely owing to the
successful spraying that he gave the trees at the proper time. I think
the future has a bright prospect for making walnut culture more
profitable.
THE PRESIDENT: We are certainly under obligations for the very
interesting talk and glad that Mr. Brooks could be with us.
The first thing on the program for the afternoon session, according to
the published program, I know will be of a most interesting character,
Top-Working Hickories, by Robert T. Morris.
TOP WORKING HICKORIES
ROBERT T. MORRIS, NEW YORK
At the present time when our views on the subject of top working trees
are based upon incomplete knowledge and experience perhaps it is unwise
to present a paper upon the subject which might be taken as
authoritative. On the other hand my experience to date is worth
recording for its face value, subject to change of view subsequently.
Different species of hickory act differently when subjected to top
working methods. The bitternut may be cut back severely without giving
evidence of any great degree of shock. The shagbark on the contrary
makes slow recovery and many years are required for a cut-back shagbark
hickory to regain normal equilibrium between top and root. The pignut
and mockernut apparently stand midway between the bitternut and the
shagbark in respect to the trimming of the top. My experience with
shagbark includes the top working of trees ranging from a few inches in
diameter up to fifteen or twenty inches in diameter, and the cutting
back has included all stages from actual felling of the tree to cutting
off half of the top or less than half of the top. The idea of felling
trees completely was to graft stump sprouts or to insert the slot bark
graft into the stump near the ground. When this has been done the larger
hickories do not send up stump sprouts at all and the root dies
excepting in cases in which a slot bark graft has been introduced. The
graft grows slowly without a great degree of vigor and requires so many
years for balancing the root that the method has not been practical up
to the present time. The same statement is true of the shagbark hickory
which has been trimmed back very severely leaving nothing but the stubs
of large branches to be grafted immediately or for the purpose of
grafting sprouts in the following year. The bark of the shagbark hickory
is so hard that new shoots are choked severely and many years are
required before they have a secure hold upon the stock. My final
conclusion is that we may cut shagbark limbs having a diameter of three
inches or less for the purpose of leaving grafting stubs. If a large
number of grafts are inserted in such a topworked tree or in stock
sprouts which start and are grafted in the following year the work is
successful. In order to avoid the labor of topworking a large shagbark
tree in its entirety we may graft only one or two limbs and allow stock
sprouts to grow on other limbs until both stock sprouts and graft
sprouts have become well branched. Branches carrying stock sprouts may
then be removed a few at a time year after year, leaving the graft
sprouts in charge finally.
By means of the bark slot method of grafting grafts may be inserted in
any part of a hickory tree. The bark slot method consists in using a
chisel and mallet for cutting parallel lines the width of the scion in
the bark of the stock. The tongue of bark between the parallel lines is
pried outward with the point of the chisel until the scion has been
inserted next the wood and the tongue of bark is then allowed to return
to place, leaving the scion interposed between the tongue of bark and
the wood. Rules which apply to the shagbark may be applied to all of the
hickories with which I have experimented. When cutting back the limbs in
preparation for topworking it is well to leave as many as possible of
stubs or branches of small diameter. Branches of small diameter may be
grafted by ordinary cleft grafting methods but branches of larger
diameter should be treated by the bark slot method. At the present time
and in the locality of my country place at Stamford, Connecticut, melted
paraffin suffices in place of grafting wax and melted paraffin is
brushed over the entire scion, buds and all, as well as over the wound
in the stock.
The time for cutting back hickories in preparation for topworking is
probably important and in my experience to date, autumn cutting is
preferable. The reason is that a good deal of activity is going on in
the tree before it enters into a state of winter rest and wounds are
pretty well repaired. In winter cutting there is some danger of
incomplete repair and in the springtime the free flow of sap invites the
entrance of various enemies, bacterial and fungous. Summer cutting
according to the laws of plant physiology would cause more shock to the
tree than cutting at any other time, although practically I have done
this successfully. Without regard to season for cutting in preparation
for topworking it is very important to trim cut ends very smoothly with
a sharp knife in order to remove ragged tissue left by the saw. It is
difficult to persuade employees to do this and it will not be done as a
rule unless the owner looks after the matter personally. The smoothly
trimmed end of the cut branch should immediately be protected with white
paint, melted paraffin, or some other protective covering.
What are the disadvantages of the slot bark method of topworking
hickories? The scion does not have such a secure hold upon the stock as
it does in cleft grafting and it will blow out in a high wind unless it
is protected by braces. I have found it not harmful to a tree to fasten
laths to the stock for holding the growing scion, driving galvanized
iron nails through the lath directly into the stock. Unless growing
grafts are well braced by some method the entire season's work may be
lost in two minutes of a gale preceding a thunderstorm in summer. By the
slot bark method, in other words, we may catch more grafts and lose more
grafts than by any other method with which I am familiar, but the loss
may be avoided by proper attention.