characters which can be weighed or measured. It cannot be concerned with
flavor and other characters upon which there may be disagreement and
which depend upon personal preference.
3) Characters must be avoided which vary with the treatment of the
samples themselves such as color of kernels.
4) It must give a score that will separate samples on small differences.
Considering the problem from these angles and scrutinizing the older
schedules, a number of ideas came out. First of all, why include the
shells? If shells are discarded a number of problems would be solved,
such as the cleaning of the nuts and adjustments for shrivelled and
empty nuts. Also, why reduce any of the weights or measures to
percentages which only add to the complexity of the score? The actual
amount of kernels recovered reflects both the size of nuts and the yield
of kernels. Plumpness of the kernels is reflected in the total weight of
kernels and does not need to be considered separately.
The important elements in a score were considered to be:
1) The crackability of the nuts of the variety. This is measured by the
weight of kernels obtained in the first crack.
2) The yield of the variety. This is measured in the total weight of
kernels.
3) The marketability of the product. This can be measured by the number
of pieces in the sample. In general, the smaller the number and the
larger the size of the pieces the better the marketability.
With this general background in mind, many samples were tested and the
results published in the 1945 report[1]. In order to secure the data
needed the kernels of the individual nuts in the samples were weighed
separately.
NOTE: All samples were cracked with the (John W.) Hershey nut
cracker.
Some of the conclusions drawn from these tests were as follows:
1) Using kernel weights only gives a rapid and accurate test of
differences between varieties.
2) Ten nuts are adequate for a single sample.
3) The location of the tree with reference to climate and soil is
probably the most important single factor influencing kernel yield. No
evidence was obtained, however, to indicate that the varieties ranked
significantly different at different locations.
4) If reasonable care is used in cracking the differences due to
different operators tend to be non-significant.
The statistical proof that a ten-nut sample is adequate and that
differences between operators are not significant are two findings that
are important in setting up a schedule.
During the past year further testing has been done, in which scores were
computed from ten-nut samples.[A] The samples had preliminary cool, dry
storage to assure comparable moisture content. Enough nuts were cracked
in each sample to secure ten that were well filled. Empty nuts were
recorded. The following data were kept for each sample:
1) The weight of the kernels recovered in first crack in grams.
2) The total weight of the kernels in grams.
3) The number of quarters and number of halves recovered.
Scores were computed as 1) the weight of the first crack in grams plus
2) half of the total weight of the kernels recovered in grams plus 3)
the number of quarters divided by four and, 4) the number of halves
divided by two. In this score, it was considered that the crackability
of the sample was measured by the weight of the first crack; the yield,
by the total weight of kernels secured from the sample; the
marketability by the number of quarters and halves. From the use of this
schedule scores were secured ranging from 83.9 for the variety Thomas
grown in Maryland to 37.4 for the variety Huen, which is a small nut
giving relatively small kernel yield.
Analyses of the data to determine the percentage of the score that was
derived from each component showed that crackability as measured by the
weight of the kernels recovered in first crack gave an average of 54% of
the score with a range of 49 to 58 for the different samples; yield, as
measured by total weight of kernels divided by two, 31% with range of 27
to 34%; marketability measured by number of quarters divided by four 14%
with range of 10 to 22% and number of halves divided by two 1%. The
percentage of the score derived from the number of halves was so small
as to be negligible. It seemed better, therefore, to base the score on
only three elements, namely, the weight of the first crack, the total
yield of kernels and the number of quarters recovered from the sample.
On this basis the problem becomes that of deciding the weights that
should be given to these three components. The score as set up
emphasizes the crackability of the variety much more than its
marketability. This seems logical because the value of a variety is in
large part dependent upon the ease of recovery of the kernels on first
cracking. Several different combinations of the weighting of these three
components were considered and it was decided that the most logical was
to weight the elements as follows: 1) The weight of first crack in
grams. 2) The total weight of the kernels divided by two and 3) the
number of quarters recovered divided by 2. If there are halves, each
half would count as two quarters.
Table I. Average scores from 18 black walnut samples cracked by three
operators and computed by two scoring systems.
Scoring Systems[3]
--------------------
Variety Source Year I II
points points
Thomas Maryland '46 83.9 93.1
Snyder Ithaca, N. Y. (A) '46 81.8 89.2
Ohio Maryland '46 79.5 88.9
Thomas Ithaca, N. Y. (A) '46 76.4 85.5
Norris Tennessee '45 76.1 83.9
Stambaugh Ithaca, N. Y. (A) '46 75.9 81.0
Stambaugh Ithaca, N. Y. (A) '46 74.0 83.2
Thomas Tennessee '45 71.5 79.6
Thomas Ithaca, N. Y. (B) '46 65.7 74.6
Cornell Ithaca, N. Y. (C) '46 59.3 67.6
Stabler Maryland '45 56.9 64.5
Cresco Ithaca, N. Y. (A) '46 55.8 65.2
Seedling No. 1 Geneva, N. Y. '46 52.7 62.2
Seedling No. 3 Geneva, N. Y. '46 50.6 59.0
Brown Ohio '45 49.7 59.4
Stabler Tennessee '45 47.5 51.4
Seedling No. 2 Geneva, N. Y. '46 44.4 52.2
Huen Iowa '46 37.4 44.9
Least significant difference (5%) 6.3 6.6
[Footnote 3: Score I=Weight (grams) 1st crack + Total weight (grams) +
--------------------
2
Number quarters + Number halves
--------------- -------------
4 2
Score II=Weight (grams) 1st crack +
Total weight (grams) +
--------------------
2
Number quarters
---------------
2 ]
Calculating the percentage of each component in the total score on this
basis gives crackability 48%, yield 27%, marketability 25%. This
schedule gives relatively more weight to marketability as against the
other two components. The average scores of 18 samples cracked by three
operators and calculated on both the above described schedules are given
in table I.
The table shows that the rank of the different samples was not changed
materially by using only the three components, except in a few cases in
which there were an appreciable number of halves. The Stabler has many
one-lobed nuts which increase the number of halves recovered. It is to
be noted that with both schedules the least significant difference at
the 5% level is about 6 score points.
Table II gives the score calculated by schedule II for five samples,
each cracked by six operators. The difference between operators is not
significant but the difference between varieties is highly significant.
Table II. Scores from five samples of black walnuts each cracked by six
operators according to scoring schedule II.
Operators
----------------------------------
Variety Location Year 1 2 3 4 5 6 Average
Snyder Ithaca, N. Y. '46 89.2 87.3 78.9 94.4 87.5 91.5 86.5
Thomas Ithaca, N. Y. (A) '46 83.5 79.2 83.1 78.0 84.2 83.8 83.6
Thomas Ithaca, N. Y. (B) '46 73.1 67.4 73.4 74.1 69.6 83.8 73.6
Cresco Ithaca, N. Y. '46 66.0 69.2 63.1 67.2 68.5 60.2 65.7
Brown Ohio '45 62.5 51.0 65.4 60.4 48.1 64.8 58.7
-------------------------------------------------------------------------
Average 74.9 70.8 72.8 72.8 71.6 78.8 73.6
Least significant difference (5%) for variety averages 6.2
A third scoring system, involving 1) weight of kernels in grams for the
first crack, plus 2) total weight of kernels, 3) all divided by the
number of marketable pieces (as counted following sifting on a 1/4"
round hole screen) was tried, and the resulting ranking of the varieties
was very similar to that obtained with systems I and II. The results
from this system appeared to be the most precise, but it was not
considered as generally acceptable as system II, since the latter would
be easier to record and calculate.
It is the opinion of the authors that Schedule II gives a score that
estimates very well the relative merit of the samples tested as to
crackability, yield and marketability. It is simple to use and the only
equipment required is a scale accurate to 1/10 gram. Calculations are
reduced to a minimum and the characters used are not dependent on
judgment of the individual making the test. It should be pointed out,
however, that differences in score of less than six points are not
significant on the basis of testing done to date. As more tests are made
this value may be reduced. The schedule should serve as a measure to
establish differences between varieties, particularly when a
considerable number of tests are made. It can also be relied upon to
measure differences due to the location of trees of the same variety,
variation of the same variety from year to year in the same and in
different locations and differences of a similar nature. In ranking
varieties which have scores within the limits of variability, it will be
necessary to use judgment as to small differences of appearance. No
scoring schedule can be expected to entirely eliminate the judgment of
experts. Also it must be realized that characters other than the nuts,
such as bearing habit, hardiness, yield of trees, disease resistance
and the like must be considered in finally establishing the value of a
variety.
References Cited
1. Atwood. S. S. and L. H. MacDaniels. Tests of black walnut varieties
for differences in kernel yields. N.N.G.A Rept. 36: 44-50, 1945.
2. Berhow, Seward. Black walnut variety tabulations. N.N.G.A Rept. 36:
38-43, 1945.
3. Bixby, W. G. Judging nuts. N.N.G.A. Rept. 10: 122-133, 1919.
4. ----. The 1929 contests and the method of testing used. N.N.G.A. Rept.
22: 42-63, 1931.
5. Drake, N. F. Judging black walnuts. N.N.G.A. Rept. 22: 130-137, 1931.
6. ----. Black walnut varieties. N.N.G.A. Rept. 26: 66-71, 1935.
7. Kline, L. V., and S. B. Chase. Compilation of data on nut weight and
kernel percentage of black walnut selections. Am. Soc. Hort.
Sci. Proc. 38: 166-174, 1941.
8. Kline, L. V. A method of evaluating the nuts of black walnut
varieties. Am. Soc. Hort. Sci. Proc. 41: 136-144, 1942.
9. Lounsberry, C. C. Measurements of walnuts of United States.
N.N.G.A. Rept. 31: 162-127, 1940
10. MacDaniels, L. H. Report of committee on varieties and judging
standards. N.N.G.A. Rept. 28: 20-23, 1937.
11. ----. Is it possible to devise a satisfactory judging schedule for
black walnuts? N.N.G.A. Rept. 30: 24-27, 1939.
12. ----, and J. E. Wilde. Further tests with black walnut varieties.
N.N.G.A. Rept. 34: 64-82, 1943.
Test Plantings of Thomas Black Walnut in the Tennessee Valley
SPENCER B. CHASE, Tennessee Valley Authority
Native black walnut occurs abundantly throughout most of the Tennessee
Valley. Practically every farmer has at least one "favorite tree" and
each fall he collects nuts from that tree and stores them for cracking
during the winter. In some sections of the Valley walnut cracking in the
home is of considerable importance. Each year, some million and a
quarter pounds of kernels are cracked out at the five modern cracking
plants located in or adjacent to the Valley. Utilization of the crop is
becoming more and more complete.
In early studies of native nut trees, TVA recognized the possibilities
of black walnut, especially the improved varieties. Here was a tree that
produced not only valuable nut crops but also cabinet wood without
equal; in addition, it was a desirable pasture shade tree. Black walnut
has long been a favorite among farmers, but few of them had ever heard
of =improved= black walnuts. Along with TVA, the state agricultural
extension services saw the advantages of the improved varieties and were
eager to test them under Valley conditions. And so it was that a
cooperative testing project was developed. TVA produced the trees and
the seven Valley state extension services distributed them to farmers
for test planting.
The Test
The Thomas walnut was used in these test plantings for several reasons.
In the first place, it produces large, rather thin-shelled nuts with
good cracking qualities. Few varieties are more easily cracked with a
hammer or a hand-operated cracking machine. In addition, fast growth is
characteristic of the variety and it should produce merchantable sawlogs
earlier than the common walnut. Despite its northern origin, 5-year-old
plantings at Norris, Tennessee, seemed well adapted to Valley
conditions. No other variety at the time offered as many advantages.
Test planting was begun in Tennessee in 1939 and then it was extended to
the other Valley states as more trees were propagated. For the most
part, planting sites were selected by extension foresters and county
agents. If the tests were successful they would automatically become
demonstrations, so special attention was given those areas where walnut
cracking in the home was an important enterprise. Many of the test
plantings were located in communities that had been organized for the
study and application of improved farming methods. In general, farmers
planted the trees in low, fertile spots not suitable for other uses,
along fences, or in pastures if they could be protected from livestock.
Through 1946, 9,614 trees were planted in 3,286 test plantings. They
were scattered all over the Valley, in 92 of its 125 counties. The
number of trees per planting varied with the availability of good walnut
sites. Generally, there were 2 to 4 trees in each planting.
The Results
Getting survival and performance data on these widely scattered
experimental plantings presented quite a problem. Examination of a few
plantings showed that trees given reasonable care had survived and were
beginning to bear nuts. So in 1946, the farmers who had planted the
trees were polled by mail for an overall evaluation of the plantings.
Questionnaires asking for information on survival, growth, and bearing
were sent by the state extension foresters to 3,274 farmers. The return
of questionnaires was excellent. Forty-two percent came back and
three-fourths of them were filled out completely.
=Survival and Mortality Causes.= Eighty-one percent of the 1,373 plantings
reported on were still active in 1946; that is, they still had at least
one living tree. Survival reports received on 3,831 trees planted showed
that 2,439 or 64 percent of the trees were living in 1946. Survival was
best in the portion of the Valley north and east of Chattanooga; 84
percent in Virginia, 71 percent in North Carolina, and 66 percent in
eastern Tennessee. South and west of Chattanooga survival percent was
lower: 62 in Georgia, 61 in western Tennessee, 54 in Kentucky, 45 in
Alabama, and 26 in Mississippi (Table 1).
Causes of mortality, as reported, were classified in five categories;
losses prior to establishment, livestock and destruction, drought,
insects and disease, and unknown (Table 1). Cause of mortality was
listed as unknown for 42 percent of all trees reported dead. Field
experience leads us to believe that most of the trees in this category
probably succumbed to improper planting or complete neglect following
planting. Many persons do not follow planting instructions; they often
substitute their own methods with disastrous results.
Among the reported known causes, drought killed most of the trees--29
percent. We know black walnut is very susceptible to dry weather after
transplanting. Weather records for the area show that the early growing
season of 1941 was exceptionally dry; 1942 was also drier that average;
in 1943 and 1944 near drought and drought conditions prevailed
throughout most of the Tennessee Valley. Weather is usually blamed when
a tree dies without apparent cause, but in this case the reported
mortality due to drought appears reasonable.
Livestock, mowing, fire, and intentional removal were reported to have
caused 13 percent of total mortality. Cows are curious animals and newly
set trees seem to arouse all the curiosity in their make-up. Horses and
cows apparently do not relish the foliage of walnut trees but they do
bite at it, and in so doing usually break down the branches to such an
extent that the tree dies. Some trees were accidentally destroyed simply
because they had been forgotten. The next highest mortality cause
reported was pre-establishment loss; this was blamed for 9 percent of
the deaths. Losses resulting from delayed planting were placed in this
category, also those where the report was "trees failed to leaf out."
Insects and diseases were reported as causing 7 percent of the
mortality.
=Growth and Bearing.= Those who plant improved black walnut trees
naturally want to know how soon they will begin bearing. This survey
shows that bearing begins much earlier than most people thought. Trees
in 32 percent of the plantings established between 1939 and 1944 were
bearing by 1946. Of these 342, 113 began bearing 2 to 4 years after
planting; 120 bore their first crop after 5 years; 109 began bearing
after 6 to 8 years (Table 2). According to the reports, the earlier
plantings were slower to come into bearing than the later plantings.
This probably is not a true picture. We suspect that after six or eight
years the actual date of first bearing had been forgotten in many cases.
Growth was reported in terms of total height for each tree. These
heights were then converted to annual growth rates for trees 3 to 8
years old and placed in arbitrary classes are follows: low (less than 1
foot) medium (1 to 2 feet), and high (over 2 feet). Test plantings in
North Carolina had the highest growth rate; those in Mississippi, the
lowest. In other states, growth rates fell between these two and were
quite similar for the most part (Table 3). Average for all trees was 1.6
feet per year. Trees averaging less than one foot of height growth per
year were slow to come into bearing. Only 14 percent of the trees in the
low growth rate class were bearing. On the other hand, 71 percent of the
trees with a high growth rate had come into bearing. Growth of black
walnut, following recovery from transplanting shock, depends on site
conditions and tree care. Trees set in fertile soil with an adequate
moisture supply and kept free of livestock and other damage make rapid
growth. Trees set in poor, thin or droughty soil do not make much growth
if they survive at all. Black walnut is very sensitive to any wounds
and, if subject to mechanical or livestock damage, growth is retarded.
Cases of exceptional growth and bearing were reported. One in eastern
Tennessee is worthy of brief description. There were two trees in this
planting set approximately 40 feet apart. One was on the edge of a
garden; the other, in a chicken run. In seven years the first tree grew
to a height of 32 feet--an average growth of 4.5 feet a year. It began
bearing in 1943 and produced a crop of nuts each year up to the time of
the survey. The 1946 crop, reported as a light one, yielded 3.5 pounds
of kernels. The other tree, shown in Figure 1, was 18 feet tall, having
averaged 2.5 feet a year. It also began bearing annual crops in 1943,
and in 1946 it had a very heavy crop for its size, yielding 2.5 pounds
of kernels. Here are two Thomas trees of the same age planted
practically side by side; one is almost twice the size of the other, but
they both began bearing annual crops three years after planting.
=Field Survey in Sample Area.= To check on the adequacy of the
questionnaire survey, 108 test plantings in eastern Tennessee were
visited and inspected. Forty of these had been reported on by mail; 68
had not. In general, the trees had been planted on the best sites
available. Some were set out in farm orchards (Figure 2); a large number
were planted in yards as combination nut and shade trees (Figure 3).
Field examination of the 40 plantings which had returned questionnaires
revealed conditions very similar to those reported (Table 4). Survival
was found to be 75 percent compared with a reported 77 percent. Average
tree height was reported as 9 feet; actual height averaged 11 feet.
There was some hesitancy in reporting tree deaths caused by livestock; 4
percent was reported while 23 percent was found. Such mortality was
usually listed as unknown on questionnaires.
Information collected by field examination of 68 plantings which had not
returned questionnaires and the 40 plantings which had returned
questionnaires is shown in Table 4. Trees were found to be 2 feet taller
in the 68 plantings but these trees averaged one year older than trees
in the 40 plantings. Trees in the 68 plantings averaged 13 feet in
height compared with 11 feet. Average age at first bearing was very
similar. And here is a revealing discovery; livestock, mowing, and fire
were responsible for 47 percent of the tree mortality in the 68-planting
group, compared with 23 percent in the 40 plantings. This is perhaps one
reason why the persons involved in these 68 plantings did not return
questionnaires; it also explains most of the poorer survival. A large
number of trees were planted in pastures and elsewhere without adequate
protection from livestock. Even when cattle guards were used they were
generally too small or weak for tree protection. Severe livestock damage
resulting in poor growth and eventual death of trees was encountered
frequently. We are inclined to believe that livestock accounted for a
much higher percent of tree mortality than that reported in this survey.
The high percent return of questionnaires in this survey, followed by a
field check in a sample area, provides a good picture of Valley-wide
plantings. Since survival was found to be lower in plantings which did
not return questionnaires, an actual overall survival of 64 percent may
be slightly high. Other spot checks in the field will give more
information on this point.
Discussion
Interest in improved black walnut is mounting in the Valley. As the test
plantings came into bearing farmers were quick to see the superiority of
these nuts over the wild ones to which they had been accustomed. Word
spread from farm to farm, and as a result there has been an increasingly
large number of inquiries about sources of improved varieties and
cultural treatments. The interest was reflected in the questionnaire
survey. Nineteen percent of the questionnaires returned contained
unsolicited comments of one kind or another. A large percentage of them
showed evidence of interest such as: "the nuts are large and easy to
crack," "where can I get more grafted trees?" Only 7 percent implied
disinterest: "the trees are slow growing," "the nuts are faulty."
This test-planting project will be completed in 1948. The plantings have
already yielded much valuable information on the Thomas variety; they
will yield much more as the trees become older. Further studies are
planned on nut yield, nut quality, and tree growth in relation to the
varying conditions existing in the Tennessee Valley.
Summary
Farmers in the seven Tennessee Valley states established 3,286 test
plantings of Thomas black walnut in cooperation with state extension
services and TVA during the period 1939-1946. A questionnaire survey in
1946 showed 81 per cent of the plantings still active and 64 percent of
the trees living. Tree growth averaged 1.6 feet per year. Age at first
bearing varied from 2 to 8 years, with 5 years most frequently reported.