SampleTreatmentWt 1 nutgrams% kernel1st crack% kerneltotalQuartersnumberPenaltyScoreRemarks9*Dry16.925.827.198—0.572.71 shr., 5 bnd. qtrs., 7 halves10*Dry16.823.825.295—3.083.51 empty, 4 shr., 7 bnd. qtrs.12*Dry16.224.525.597—2.086.14 shr., 8 bnd. qtrs., 13 halves24*Dry16.224.825.786—3.084.22 empty, 2 shr., 4 bnd. qtrs., 8 halves17*Dry17.324.827.397—0.589.71 shr., 9 bnd. qtrs., 12 halves21*Dry15.922.025.596—4.078.21 empty, 6 shr., 14 bnd. qtrs., 17 halves8*Dry16.625.226.999—1.588.83 shr., 6 bnd. qtrs., 10 halves15*Dry16.625.526.799—1.589.83 shr., 5 bnd. qtrs., 12 halves23*Dry16.425.226.296—3.087.06 shr., 4 bnd. qtrs., 10 halves11Soaked16.927.028.2100—1.593.5Soaked 1 hr., moist 18, dried 12 hrs.,3 shr., 5 bnd. qtrs., 25 halves16Soaked16.827.128.2100—0.894.3Soaked as above, 1 shr., 5 bnd. qtrs., 16 halves4Dry16.223.626.498—3.582.97 shr., 10 bnd. qtrs., 15 halves5Dry17.123.625.093—3.083.11 empty, 6 shr., 5 bnd. qtrs., 10 halves18Dry17.025.326.697—2.088.64 shr., 6 bnd. qtrs., 8 halves19Dry16.321.523.785—4.575.13 empty, 3 shr., 9 bnd. qtrs., 8 halves3Dry15.424.727.097—3.085.06 shr., 8 bnd. qtrs., 5 halves7Dry16.025.725.794—3.586.17 shr., 6 halves, end reversed in cracking22Dry17.424.125.894—2.585.45 shr., 8 bnd. qtrs.
SampleTreatmentWt 1 nutgrams% kernel1st crack% kerneltotalQuartersnumberScoreOperator 1Thomas—Jones, Pa.14.628.830.39596.8Thomas—Baum, Pa.14.325.627.010089.0Thomas—Worton, Md.16.428.230.89497.6Average16.425.828.191.091.2Operator 2Thomas—Weber, Ind.22.022.223.84783.0Thomas—Jones, Pa.17.526.731.45592.1Thomas—Baum, Pa.17.024.026.57285.5Thomas—Worton, Md.16.719.526.46475.3Average18.323.127.059.583.9Operator 3Thomas—Jones, Pa.18.116.227.15269.2Thomas—Baum, Pa.16.119.126.66874.4Thomas—Worton, Md.18.017.827.26173.3Average17.417.727.060.372.3Operator 1Ten Eyck—Weber, Ind.18.020.527.55778.5Ten Eyck—Jones, Pa.15.421.123.29979.1Ten Eyck—Baum, Pa.14.326.330.29391.3Ten Eyck—Worton, Md.15.028.031.08394.8Average15.724.028.083.085.9Operator 2Ten Eyck—Weber, Ind.19.124.426.53884.8Ten Eyck—Jones, Pa.16.424.624.66484.3Ten Eyck—Baum, Pa.15.825.726.55486.0Ten Eyck—Worton, Md.15.425.528.75586.2Average16.725.026.652.785.3Operator 3Ten Eyck—Weber, Ind.16.817.324.65769.4Ten Eyck—Jones, Pa.15.221.123.38477.4Ten Eyck—Baum, Pa.15.018.319.76968.4Ten Eyck—Worton, Md.15.725.230.17688.5Average15.720.524.471.575.9Operator 1Ohio—Weber, Ind.17.228.529.78998.0Ohio—Jones, Pa.16.428.729.99699.2Ohio—Baum, Pa.14.231.131.199101.9Ohio—Worton, Md.13.730.830.88899.5Average15.429.830.493.099.6Operator 2Ohio—Weber, Ind.19.125.128.35989.3Ohio—Jones, Pa.17.227.327.56491.9Ohio—Baum, Pa.15.027.428.16390.1Ohio—Worton, Md.14.926.129.15887.4Average16.526.528.261.089.7Operator 3Ohio—Weber, Ind.17.721.427.76580.8Ohio—Jones, Pa.17.222.928.27484.5Ohio—Baum, Pa.15.024.929.38187.5Ohio—Worton, Md.14.622.428.76680.3Average16.122.928.571.583.3
Table 4 gives the results of tests of similar samples of three varieties from four different sources by three different operators. The tests are not satisfactory because pretreatment was not uniform and there is insufficient data on penalties which are omitted. Some samples of the varieties Ten Eyck and Thomas contained empty nuts and shrivelled kernels which would preclude equal scores. The variety Ohio was uniformly filled from all sources. In the variety Ten Eyck there is a difference of 10.5 per cent in total per cent kernel in samples from the Baum orchard. This was related to 6 empty nuts in the sample cracked by operator 3. In the variety Ohio in which the kernels were plump the greatest variation between duplicate samples in total per cent kernel is 3 or only about 10 per cent of average total per cent kernel.
An examination of these data show the following points of interest: (1) that the duplicate samples showed considerable variation in weight of single nut and total per cent kernel, characters not dependent on personal skill or judgment. Operator 2 did not crack the whole sample of 25 and may have selected the larger nuts, thus securing a greater weight per nut with all varieties. The superior filling of the nuts of Ohio appears to be related to the fact that in the orchards in question this variety was observed to hold its leaves longer than the others which lost their leaves in late summer before harvest by leaf blight. Shrunken kernels are a logical result of early defoliation.
In the per cent of kernel obtained in first crack operator 1 recovered a higher per cent than operator 3 in all of the eleven possible comparisons and higher than operator 2 in 9 out of 12 possible comparisons. This probably is the result of soaking the samples by operator 1 and not by the others or possibly due to greater skill or care in cracking. The number of quarters recovered by operator 1 is greater in all cases than that obtained by either operator 2 or 3. This is also a result of soaking or skill or both. The score of operator 1 was in all tests of duplicate samples higher than that obtained by operator 3 and higher than the scores of operator 2 in 9 out of 12 comparisons.
The scores of the different samples are apparently mainly determined by the per cent recovered at first crack and the number of quarters, at least the only cases where the scores of operator 2 exceed those of operator 1 are where the per cent first crack and the number of quarters are greater for operator 2. This is related to the presence of empty nuts.
The data obtained for the variety Thomas by operator 1 and 2 show for the most part the same relative scoring of samples from different sources. For example with both operators the score of the samples from the Weber orchard was lower than that from the Jones and Baum orchards and the sample from the Jones orchard scored higher than that from the Baum orchard. In the samples from the Worton orchard the relative scores are reversed. The scores o£ operator 3 are quite out of line. With the variety Ten Eyck the differences between scores of samples from different sources are not consistent. Operator 2 obtained scores that were essentially alike for all four samples whereas the scores of operator 1 show differences of more than 10 points. This is related to empty nuts in the sample. With the variety Ohio there is reasonable uniformity in the scores obtained by all operators. This was the only variety with well filled nuts and for that reason alone the score would be less variable.
SampleTreatmentWt 1 nutgrams% kernel1st crack% kerneltotalQuartersnumberPenaltyScoreRemarksOperator 1Ohio No. 1Dry16.826.127.697—4.88.55 bnd. qtrs., 18 shr., 8 halvesOhio No. 2Soaked16.727.327.899—1.593.52 bnd. qtrs., 1 shr., 1 emptyOperator 2Ohio No. 6Dry15.926.326.793—1.90.21 emptyOhio No. 13Soaked15.925.826.493—1.89.01 emptyOhio No. 14Soaked15.725.226.396—.589.01 shriveledOhio No. 20Soaked16.725.326.494—1.88.91 emptyOperator 1Grundy No. 1Dry23.824.124.699—.593.71 shriveled, 2 bnd. quartersGrundy No. 2Soaked23.224.224.2100—.597.21 shriveled, 2 bnd. quartersOperator 2Grundy No. 322.424.024.088—2.89.22 emptyGrundy No. 4Dry23.524.725.598—.595.01 shriveledOperator 1Adams No. 1Dry14.218.324.570—0.70.035 bnd. qtrs., well filled, good qualityAdams No. 2Soaked14.417.323.778—2.567.12 empty, 20 bund. qtrs., 1 shr.Operator 2Adams No. 3Dry14.618.124.077—367.53 emptyAdams No. 414.319.625.478—372.32 empty
The average scores of all samples of each variety are Ohio 90.0, Thomas 83.4, and Ten Eyck 82.4. These are not out of line either with the scores obtained for these varieties elsewhere or the relative merit of the varieties.
Because of the variability obtained in the tests shown in Table 4, another series of tests of similar samples by different operators was arranged in the summer of 1943. The samples of Ohio were some of the same lot reported in Table 3. The varieties Grundy and Adams grown in Michigan were carefully sampled to give comparable lots. The results of these tests given in Table 5 show no greater variability between the scores of the two operators for any one variety than between tests by the same operator and indicate that it is possible for different operators to obtain comparable scores on duplicate samples provided great care is used in treating and cracking the samples.
The differences in average score between the different varieties is consistent and apparently gives a correct indication of their relative merit. Grundy shows an average score of 93.7, Ohio 89.7 and Adams 69.2. The high score of Grundy is related to the large size of nut and high per cent first crack. The low score of Adams is related to small size of nut and low per cent first crack resulting from a large number of bound quarters. The kernels of this variety were plump, filling the cavity of the shell full and shattered on cracking.
In Table 6 are given the results of 54 tests of 38 selections or clones. In general it appears that the score is a fair indication of the worth of the sample. Low scores are related mostly to low per cent first crack and to the presence of empty nuts or shrivelled kernels in the sample. It is evident also that if a sample is too dry with many varieties a low score will result. Just what soaking treatment is most expedient is not too clear. Soaking 12 hours and drying 24 proved to be a satisfactory practice. The method followed by Mr. Stoke of soaking for 5 minutes and keeping the sample in a wet burlap sack for 24 hours is all right but is cumbersome if many samples are to be tested. Soaking one hour and holding 24 hours in a closed container like a coffee can give good results but percentage should be figured on dry weight and kernels should be air dried for 24 hours before weighing.
One weakness in the schedule is that it tends to give a small nut an advantage if the per cent kernel obtained in first crack is high. Thus a sample of the Mintle grown in Iowa which weighed but 13.6 grams per nut and total per cent kernel of 32 scored 101.1 points chiefly because the per cent first crack was 31.5. The same variety grown at Ithaca weighing 13.7 grams per nut but with 23.9 per cent first crack and 24.3 total scored 83.8. Possibly a penalty could be taken for nuts weighing less than 18 grams. On the other hand a large nut like the Grundy weighing about 23 grams would have a 10 point score advantage over Mintle and this may be enough for this character.
The six samples of Thomas grown on different trees in Ithaca, N. Y. in 1942 show great variation in score as has been the case in other years. Poor scores are related to shrunken kernels and such samples come from trees that are making poor growth because of poor soil conditions and competition with weeds. Also shriveled kernels are the result of defoliation by early frosts which may be very local and affect some trees and not others.
VarietySourceTreat-mentWt 1 nutgrams% kernel1st crack% kerneltotalQuartersnumberPenaltyScoreRemarksAdamsBecker, Mich. '42D14.711.321.44452.4Poor; 62 bound quartersBentonSmith, Wassaic, N.Y.S-513.226.828.294-2.088.5Plump kernels, good flavor, 2 empty nutsSample No. 1 (23)'42D-8Sample No. 2 (24)'42D12.923.123.674-3.075.33 empty nutsBontzSnyder, IowaS-1218.720.322.085-10.068.8Nut long like Ohio.Shell chamberProminent spur;oily; poor to med. extr.; few shrunken'40D-12BootheStoke, Va.S-1615.324.529.287-2.585.1Good quality; flavor good,28 blind qtrs.; ext. poor'40D-10BurrowsSnyder, IowaS-1217.513.524.435-0.359.9No data'40D-4CalhounBecker, Mich. '42D15.426.028.59490.6End cracks, 2 empty nuts, 3 shr.CayugaIthaca, N.Y.S-1213.826.126.7100-3.585.9kernels, good extr.middle tree'42D-24ClimaxBecker, Mich. '42D17.225.327.39090.8Some shrunken kernelsCornellIthaca, N.Y.S-1216.524.925.18089.0(20)'42D-24100%No empty nuts, kernels fullvery good extr., good colorCreitzStoke, Va.S-1518.822.023.8100-1.383.4'404-4Excellent cracker. Shell thin;good flavor mildCrescoIthaca, N.Y.S16.715.921.08067.0(6)'42EldridgeGeneva, N. Y.S-12Not promising at Ithaca(15)'42D-2421.124.024.596—10.80.0Dried in husk; kernels shrunkenFinneySnyder, IowaS-1219.518.022.482—12.562.4Shell thick; kernels shr.,spurs prominent.Tough to crack'40D-48FreelIthaca, N.Y.S12.117.919.68065.7Shell thick, kernel thin.Not a good nut(6)'42GallowaySnyder, IowaS-1216.422.323.294mdash;0.381.7Kernel smooth, flavor good.Extraction good'40D-24HarrisSnyder, IowaS-1218.523.825.6100mdash;12.576.4Dark color. All kernelswithered. Flavor poor.Extraction very good'40D-12HomelandStoke, Va.S-519.120.425.889mdash;12.581.7Smooth kernels; flavor good;closed suture'40D-16KarnesStoke, Va.S-1620.325.629.456mdash;12.591.8Tight in shell. Kernels oily,shatter. Flavor good.Shining pellicle'40D-7KornKorn, Mich.D16.819.027.962mdash;12.574.9Kernels fill cavity very full.Shatter.'39McCoySnyder, IowaS-1219.420.721.290—0.879.6Smooth kernel;some slight shrinking.Thick shell'40D-4McGeeBecker, Mich.D13.716.226.883—0.867.8Bound qtrs., hard pointednuts, hard cracking'40D-4MichiganKorn, Mich.D20.023.030.390—0.890.1Kernels plump, very good nut'39MintleSnyder, IowaS-1213.631.532.095—1.0101.1Flavor mild, extr. verygood. Very good nut,smooth shell'40D-12MintleIthaca, N.Y.S-1213.723.924.3100100No empty nuts, kernelsplump, good extraction'42D-24OhioSnyder, IowaS-1218.524.027.479—1.386.8Shell chamber smooth.Flavor sharp.Extraction fair.'40D-24RohwerSnyder, IowaS-1221.524.028.28492.0Kernel smooth, extr.fair. Kernels plump.'40D-48RohwerStoke, Va.S-1518.518.022.479—.373.3Fair extraction; flavor fair.Spur prominent.11 blind qtrs.'40D-3SchwartzSnyder, IowaS-620.321.825.686—3.082.2End cracked. Spurs prominent.Some shrinking. Nottoo good. 11 blind qtr.'40D-14SiffordStokes, Va.S-1623.623.725.6100—11.082.8Large nut. Goodextr. Kernels shrunken'40D-7SnyderJacobs, OhioD19.626.128.094—11.095.4Not entirely cured(4)'42D-7SnyderSmith, Wassaic, N.Y.D21.922.026.49188.211 bound qtrs. Kernels lg.rather dark, a good nut(14)'42SparrowIthaca, N.Y.S-1215.520.722.442—14.563.21 empty, all shrunken,end cracks; poor quality(11)'42D-2496%SparrowSmith, Wassaic, N.Y.D16.521.628.285—14.582.3Well filled, kernelsbright, good flavor,good nut(10)'42D-24SparrowSnyder, IowaS-616.125.131.284—14.590.3Flavor good; smooth nut,spur medium prominent.13 blind qtrs.'40D-19SperBecker, Mich.'42D16.220.025.69078.0Kernels somewhat shrunken'42D16.727.928.79896.6No. 4, 1942 not completelydried. Not recleanedStablerStoke, Va.S-514.520.222.880—9.065.3Flavor mild. Easy extr.12 blind qtrs. Many shrunken'40D-20StablerWilkinson, Ind.S-1214.925.727.277—3.084.6End cracks; 6 bound qtrs.2 empty nuts, 2shr. kernels'40D-24StambaughGraham, Ithaca, N.Y.(7)recleaned19.324.024.028—12.561.3All kernels shrunken.Poor quality'42S-12 D-24100%—3.0SterlingKorn, Mich.D19.825.225.99792.8Kernels plump. Very good nut'39TasteriteGraham, Ithaca, N.Y.(4)recleaned13.525.025.0100%86.0All kernels plump;quality fair'42S-12 D-24ThomasSnyder, IowaS-1217.222.925.691—1.083.9Good extraction. Some shrunken'40D-12 D-24ThomasWilkinson, Ind.S-1218.521.527.12677.7End cracks; 21 bound qtrs.,Kernels plump; oily, clinging'40D-24Thomas No. 1Ithaca, N.Y.D20.619.122.19679.4Some shrunkenTree 1 '42.Thomas No. 2Ithaca, N.Y.S-1½20.614.418.291—1.067.61 empty nut; some shrunkenNo. 2 '42D-6Thomas No. 3Ithaca N.Y.D20.419.122.196—1.079.2No. 3 '42Thomas No. 4 '42Ithaca N.Y.D20.115.516.882—16.036.24 empty nuts; all shrunkenNo. 4Thomas No. 5Ithaca N.Y.S-1220.523.424.090—8.080.54 empty nuts; 8 shr.kernels; 2 blind qtrs.(24)No. 4ThomasIthaca N.Y.S-1219.817.618.494—10.063.72 empty nuts; 16 shr. kernels(20)No. 6 '42D-24ThomasWilkinson, Ind.S-1220.521.125.469—7.075.33 empty nuts; 4 shr. kernels, 23 bound qtrs.'40D-24TroupGraham, Ithaca, N.Y.S-1216.016.018.016—20.051.0All kernels shr., 2 empty nuts, quality poor(4)'42D-24100%VailIthaca, N.Y.S-1215.320.821.8304 empty nuts, 6 shr. kern.,2 blind qtrs., end cracks(8)'42D-2494%—17.060.2VanderslootIthaca, N.Y.S-1227.513.416.658—3.064.41 empty nut, 4 shr. kern., 11 bound qtrs., ext. poorD-24WiardIowaS-1218.826.829.48395.4One of best, wellfilled. Smooth kernel,good flavor,good extraction'40D-12
In the light of the data presented some conclusions can be drawn on the various questions raised at the beginning of this paper. It is evident that if approximately the same score is to be obtained by one operator on duplicate or replicate random samples, great care must be used in sampling. There is a tendency in taking samples to pick out the larger nuts or in some other way fail to take a good random sample. Selections submitted for contests are likely to be quite misleading as to the value of the variety and reflect in considerable part the contestant's skill in selection rather than the merit of the clone. The Freel walnut seems to be an example of this. At least as grown at Ithaca it is very disappointing.
It is evident that if comparable scores are to be obtained the samples receive the same treatment particularly as regards moisture content. Samples should be dried sufficiently to show the shrinkage of poorly developed kernels but in no case be allowed to dry to the point of checking the shells. Uniform soaking practice is a step in the right direction. A green or partially dried nut will test much higher than one properly cured as evidenced by Snyder, sample 6 and Spear, sample 7 in Table 1.
It seems probable that no schedule can be devised that will eliminate the necessity for skill on the part of the operator. To obtain satisfactory uniformity in scores, it is essential that the operator be skilled in the use of the cracking machine and use continuous care in applying the necessary pressure and in holding the nut in the anvils. Undercracking or overcracking, reversing the ends of the nut in the anvil or failure to hold the nut vertical may affect the score.
The presence of empty or poorly filled nuts in a lot of nuts from which samples are taken at random introduces greater variability in the samples than that found in lots with all nuts filled. This is true because the chances of getting an equal number of empty nuts in 25 nut samples are small and the presence of each empty nut decreases the per cent kernel and also the numbers of quarters possible. Variations due to empty nuts could be eliminated by greatly increasing the number of nuts in the sample but this is not practical for the purposes this schedule is intended to serve.
The question of whether or not it is possible for different operators to obtain equal scores on duplicate samples is not satisfactorily answered by the data in table 4. As the data stand the scores are far from equal. There is, however, a consistency in the scoring of each operator and it is quite probable that with more uniform treatment of nuts before cracking and more careful sampling better agreement would be achieved. This is borne out in the data given in table 5 in which the variation in scores between the two operators was no greater than that obtained by the same operator.
From a study of the data secured it appears that the causes of variation in the scores of duplicate or replicate samples are the result of (1) lack of care in making replicate random samples, (2) differences in treatment of samples before cracking, particularly as regards moisture content, (3) differences in the skill or care of the operator making the tests, (4) presence of empty nuts or shrivelled kernels in the sample which introduces variation not compensated for in a 25 nut sample and further complicates the matter because assigning penalties for shrivelled kernels involves personal judgment.
The first three of these can be minimized or eliminated by care and skill. The fourth item is not so easy but procedure can at least be standardized. Increasing the size of the sample is not practical if much testing is to be done.
All things considered it would seem that the scores indicate fairly well but not accurately the relative merit of the samples and thus can be relied upon to determine the relative merit of a variety or clone, the suitability of the variety for growing in a given locality and the variability of a variety grown in the same region but under different conditions. To determine the merit of a variety as compared to another both must be grown under the same conditions. The over-all value of a variety can only be determined from samples of well filled nuts. In any case the more samples tested the better.
The following suggestions are made as to procedure:
1. In taking a random sample no selection as to size, uniformity, or any other quality should be made. Suggested procedure would be to scoop up about 25 nuts in a berry basket or with the hands from the main supply and reduce the sample to 25 without conscious selection. What we in the Northern Nut Growers' Association want is a measure of the merit of the crop of the tree or variety in question and not the value of a highly selected sample.
2. It is not practical to bring samples to a uniform moisture content before cracking is done. The following precautions, however, may be followed: (a) Take care to see that nuts are reasonably well cleaned and free from fragments of husk. Scrubbing or beating the nuts together in a sack will usually remove most of the loose material. Of course the best practice is to wash the nuts immediately after shucking. (b) Cure samples until they are dry enough not to lose more weight preferably in an unheated room. This takes at least a month or 6 weeks. (c) Avoid storing the samples in a heated room where they will become so dry that the shells will check or crack. If this occurs the normal cracking fracture of the shell is destroyed and a satisfactory test cannot be made. (d) Nuts that have become so dry that the kernels shatter may be moistened by soaking about 2 hours in cold or lukewarm water then holding them in a moist condition for 18-24 hours, followed by drying for 10-12 hours before cracking. Nuts that are to be soaked should be weighed before soaking and the dry weight used in figuring percentages. The kernels of soaked nuts should be dried for 24 hours before weighing, preferably under the same conditions in which the samples were stored before weighing.
3. Care and skill on the part of the operator are of the greatest importance, particularly in the thoroughness of cracking. The most important variable in the score is the per cent kernel recovered at first cracking. The score is reduced by undercracking the nut so as to leave the quarters bound or by overcracking to the point of smashing the kernels. If the nuts have a long point so that the rims of the anvils do not contact the shoulders of the nut, poor cracking will result. At the present time a cracker with interchangeable anvils is not available. Using different sized iron pipe couplings in a vise may help solve the problem. Some varieties will crack better with a hammer than with a cracker of the Hershey type with standard anvils. In cracking a sample for test theoperator should try to recover the most possible out of the first crack without using a pick or recracking.
4. The empty nut problem is probably the most difficult and is not satisfactorily solved by cracking nuts in excess of 25 until 26 filled nuts are secured. This necessitates weighing the sample after the nuts are cracked which is usually impracticable because of loss of parts of shells in cracking and because additional nuts are not available. Empty or shrivelled nuts in a sample are a serious defect which should count heavily against it. On the basis of experience it seems that a better method is to crack the random sample of 25 nuts and let the empty nuts and shrivelled kernels affect the score as reduced weight per nut, reduced per cent kernel and the penalty as well. Shrivelling that is obvious and which adversely affects the appearance of the kernels should be penalized. Possibly further experience will suggest a better way of handling this problem.
The proposed score of a sample is made up as follows:
1. The weight of a single nut in grams.
2. The per cent kernel of total weight of sample recovered after first crack x 2.
3. The total per cent kernel of total weight of sample divided by 2.
4. One tenth point for each whole quarter recovered.
5. Penalty of one score point for each empty nut in the sample.
6. Penalty of ½ point for every nut with shrivelled kernel.
The makeup of this score does not differ from that previously used except in the matter of procedure with empty nuts. It is felt that the items included are weighed in a realistic manner and that difficulties in scoring have been due to methods of handling the samples rather than in the scoring schedule itself. It does not seem likely that this schedule or any schedule will be valuable unless used by experienced operators who are willing to take the precautions indicated. Also it is apparent that wherever possible more than one sample of a lot to be scored should be tested and the average score used.
1. MacDaniels, L. H. Report of committee on varieties and judging standards. No. Nut Growers Assn. Proc. 28: 20-23. 1937.
2. MacDaniels, L. H. Is it possible to devise a satisfactory judging schedule for black walnuts? No. Nut Growers Assn. Proc. 30: 24-27. 1939.
3. 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.
4. Kline, L. V. A method of evaluating the nuts of black walnut varieties. Am. Soc. Hort. Sci. Proc. 41: 136-144. 1942.
5. Lounsberry, C. C. Measurements of walnuts of United States. No. Nut Growers Assn. Proc. 31: 162-167. 1940.
6. Drake, N. F. Judging black walnuts. No. Nut Growers Assn. Proc. 22: 130-137. 1931.
7. Drake, N. F. Black walnut varieties. No. Nut Growers' Assn. Proc. 26: 66-71. 1935. Nut Growers Assn. Proc. 30: 81-83. 1939.