RESULTS OF FIELD OBSERVATIONS
BARK—Most of the shagbark hickory trees observed were found to have a smoke-gray, shaggy bark from 20 years of age to maturity. However, among the 158 individual hickory trees observed, there were found 7 trees which had a bark much more blackish than the normal shagbark type and with closely furrowed bark consisting of inter-lacing scaly ridges more similar in character to that of Carya ovalis (Wangenh.) Sarg.
The trees found growing under timberland conditions rather than as open field or hedgerow trees did not have the characteristic shaggy bark except for the upper trunk which had been exposed to the weather conditions of the forest canopy. Where the trunks of the trees were somewhat protected from direct rays of the sun and force of the wind, the bark was smooth, gray and but slightly plated with none of the shagginess typical of open field grown shagbark.
BUDS AND TWIGS—The buds of shagbark were observed to divide themselves into two general groups based upon terminal bud shapes and two more groups based upon the sizes of the attenuated apex of the outermost bud scales. In all cases the bud scales were observed to be pubescent though the degree of pubescence varied considerably in the outer scales only.
The two general bud shapes were globose-ovate and narrowly elliptical. The broadly oval (Fig. 1a) type of buds were smaller, generally under 1/2 inch in length while the elliptical (Fig. 1b) type of buds were usually over 1/2 inch in length.
[Illustration: Fig. 1a Fig. 1b
Shagbark Hickory Terminal Buds (1-X)]
The long attenuated apex on the outer bud scales of the elliptical type of buds is evident in Figs. 1b and 2b.
[Illustration: Fig. 2a Fig. 2b
Shagbark Hickory Terminal Bud Scales (1-X)]
The number of lateral buds at one position varied considerably with the usual number being one (Fig. 3a) bud located just above the lobed leaf scar. On exceedingly vigorous sprout growth, or on very vigorous terminal growth twigs, it was found that 2, 3, 4 and occasionally 5 superposed buds might occur (Fig. 3b).
Twigs of shagbark varied considerably both in the rapidity of growth and in color. Frequently the color seemed to be associated with the incident rays of the sun and orientation of the twig on the branch seemed to largely control color.
Twigs upon the same tree would vary from gray to reddish brown to yellowish brown or tan. The majority of observed trees had a reddish brown as the predominant color. Terminal shoot growth of as much as 40 inches was observed and as little as 2-3 inches in very slowly growing mature trees.
[Illustration: Fig. 3a Fig. 3b
Shagbark Hickory Lateral Buds (1-X)]
[Illustration: Fig. 4a Fig. 4b
Shagbark Hickory Leaves (1/3X)]
The degree of pubescence on the surface of the twigs varied considerably and was found to frequently follow group location patterns. Thus nearly all of the individuals growing in one field might be found with dense pubescence on the twigs while a similar group several miles away might have, for all practical purposes, no pubescence on the twigs. In general, the most rapidly growing trees (or twigs) had the least amount of pubescence on the twigs.
LEAVES—There was extreme variability found with the leaves of the 158 individual trees observed. All trees were found to have compound leaves, but the leaflet numbers varied greatly. The typical number for shagbark is 5, but 3 to 7 were found; three leaflets were common, 5 were abundant and 7 leaflets were rare. Six cases of leaves with 7 leaflets were obtained from the vast number of leaves checked on the 158 trees; thus the frequency of occurrence is quite low for the group as a whole. Where 7 leaflets were observed, 5 of the leaves were normal pinnately compound leaves (Fig. 4a), while one leaf consisted of five palmately arranged leaflets plus two normal pinnately compound leaflets (Fig. 4b). The leaflets on each tree were fairly uniform in shape but the shape of leaflets between trees varied considerably. Thus one tree might have 5 leaflets quite broadly ovate to obovate in shape while another equally valid shagbark would be found with narrowly elliptical to lanceolate leaflets similar to those of red hickory (oval pignut hickory), Carya ovalis (Wangenh.) Sarg.
[Illustration: Fig. 5a Fig. 5b Fig. 5c
Shagbark Hickory Fruits (1/2X)]
The margins of the leaflets were generally finely serrate and disposed to be ciliate—i.e. with a fringe of hairs along the serrate margins. The presence of cilia tend to differentiate shagbark hickory from red hickory in the field. This feature is a consistently good one if a hand lens is available but the degree of ciliation varies considerably from tree to tree and during different parts of the growing season. The presence of cilia on the margin of the leaflets should not be used as a means of differentiating shagbark from shellbark hickory, Carya lacinoisa (Michx. f.) Loud., since shellbark also has a ciliate margin on the leaflets.
FLOWERS—The female flowers of shagbark are found on short 1 to 5 flowered spikes produced on the current season's growth. Most of the flowers are around 1/3" long, sessile and covered with a tawny tomentum. Each flower tends to have two yellowish green stigmatic lobes but three-lobed stigmas may be found and one case of a 4-lobed stigma was observed. Various amounts of an amber, or yellow scurfy, substance was also observed on the new flowers. The male flowers occur on 3 parted, slender, glandular-hairy aments from the basal portion of the current season's growth. The aments are usually 3-4 inches long with individual flowers consisting of 4 stamens with their surrounding bract and calyx lobes. The anthers are yellowish or greenish yellow. Occasionally a two branched ament may be found but this seems to occur when one branch of the ament has failed to develop due to an injury of some sort. One case of an unbranched ament was observed.
Both female and male flowers are found to be mature after the leaves have grown to nearly their fully expanded mature size. There are more male aments to be found on the lower branches than female spikes of flowers, which would tend to aid in cross pollination of the flowers by wind action. In general the stigmatic lobes are not quite mature at the time that the bulk of the pollen is being shed, yet individual trees, at a considerable distance from another pollen bearing shagbark tree, will bear considerable quantities of nuts indicating self fertility.
FRUIT—The husk of the shagbark is extremely variable in size, shape, thickness and opening habits. In general the husk consists of 4 segments which split along 4 sutures and fall apart at maturity dropping the nut to the ground. In many cases the husk falls to the ground with the nut and does not break apart until it reaches the ground. A few of the trees examined had husks which were not quite deciduous to the base and were retained on the tree until after the nut had been released. One tree among the 158 examined consistently had a 5 parted husk.
The husks varied considerably in thickness, the dried measurements ranging from 1/8 to 1/2 inch with the bulk of the measurements averaging around 1/4" thick. Two trees had husks so thin as to be more typical of red hickory while only 6 trees had husks 1/2 inch thick or more.
The overall shape of the husk around the nut ranged from globose (Fig. 5a) to ovoid (Fig. 5b) to obovate (Fig. 5c).
It would seem that the shape of the nut enclosed within the husk might be predetermined by examination of the husk itself. The obovate husk shape could most frequently be depended on to produce either elliptical or obovate nuts but this was not an absolute certainty. The thickness of the husk effectively concealed the true shape of the nut beneath; the thinnest husks most nearly conforming to the true nut shape.
The size of the mature shagbark hickory nut and husk ranged from as small as one inch in a tree which had a seed barely 3/8" wide to as large as 2-1/4 inches. The size of husk and nut is variable and adjacent trees which may have developed from the same parent seldom have similar nuts in the area examined.
The nut itself exhibited the greatest variability of all features examined on the test trees. These trees exhibited striking dissimilarities in:
(1) nut size (2) nut shape (3) shell color (4) thickness of shell (5) sweetness or palatability of nutmeat.
One tree was discovered with a nut which might have caused a taxonomist to coin the name Carya ovata var. microcarpa due to the very small dimensions of about 3/8 x 3/8 x 3/4 inches in width, thickness and depth. Even the squirrels of the area did not feel that this tree deserved their attention The largest nut obtained had overall dimensions of 1 x 3/4 x 1 inches in width, thickness and depth. The majority of average sized nuts were roughly 3/4 x 1/2 x 3/4 inches.
The nut shapes have fallen into a general pattern which include the following normal types:
Type A—The normal 4 angled nut, nearly rectangular in cross section
(Fig. 6a).
Type B—An elliptical form, nearly oval in cross section (Fig. 6b).
Type C—A smooth oval nut, oval or elliptical in cross section (Fig. 6c).
Type D—An obovate nut, oval to angled in cross section (Fig. 6d).
Type E—A fat globose nut, broadly oval to orbicular in cross section (Fig. 6e).
[Illustration: Type A Type B Type C Type D Type E
Fig. 6a Fig. 6b Fig. 6c Fig. 6d Fig. 6e
Normal Fruit Forms of Shagbark Hickory (1X)]
[Illustration: Type F Type G Type H
Fig. 6f Fig. 6g Fig. 6h
Abnormal Fruit Forms of Shagbark Hickory (1X)]
In addition to the afore mentioned 5 normal types, three abnormal types were encountered:
Type F—A smooth or angled nut, triangular in cross section—found
in the same trees as normal nut forms (Fig. 6f).
Type G—A smooth or angled nut square in cross section—found
on the same trees as normal nut forms (Fig. 6g).
Type H—A Siamese twin form occurring very rarely on the same
trees as other normal forms (Fig. 6h).
Type A was the commonest form of nut found in the Onondaga County area. It roughly exceeded Types B, D and E by a 2:1 ratio. Type C exceeded Types B, D and E with a ratio of about 7:5 in frequency of occurrence. Types B and D were the two most easily cracked nut forms when using a hammer and anvil for a cracking device. It should be noted at this time that all of the abnormal fruit types were found in conjunction with normal fruit types. Thus, one individual tree used as a collection might produce both a normal nut type (A, B, C, D or E) and an abnormal nut type (F, G or H). Occasionally a few nuts in a collection from one tree might be classed as a second normal type. This was rare however (5 cases) and only occurred in "borderline trees" which were then classified and recorded as per the dominant nut type for the tree. It should be noted here that the nut type did not vary from year to year for the trees examined. Also the frequency of nut crops varied considerably; less than 1/4 of the sample trees produced nuts each year. Most of the trees produced crops in alternate years, and a very few have not fruited in the third year following a heavy nut crop.
The 158 trees examined provided the following distribution by fruit types:
———————-+—————————+————————————————
| Number of | Number of abnormal types found
Fruit Type | Individual Trees | in conjunction with
| | normal types
—————-+—-+—————————+————————————————
| | | F G H
—————-+—-+—————————+————————————————
Normal | A | 54 | 5 2 1
| B | 23 | 2 1
| C | 36 | 1 2
| D | 21 | 7 1
| E | 24 | 4 1
—————-|—-+—————————+————————————————
| | 158 collections |
—————-+—-+—————————+————————————————
Abnormal | F | 15 | 15
| G | 8 | 8
| H | 4 | 4
———————-+—————————+————————————————
27 collections
Shell color of the nuts varied between a brownish white and a pinkish white color when fully dried. From the trees used as a sample, there were 14 which might be classed in the brownish white categories, and the remainder (144) as pinkish white or creamy white. Types B and C were the ones which most frequently were found with the brownish white nutshell color. Type A was typically pinkish or creamy white in color.
Nutshell thickness varied somewhat. In all but 2 cases, the nuts were too hard to crack with the teeth. The thin-shelled ones are comparatively thin only, being about like paper-shelled pecans with the shell thinnest on the sides of the nut. It is not suggested that these two thin-shelled nuts be exploited as paper-shelled shagbarks since they are poorly formed nuts and of small size. One of the two trees might be a hybrid since it does not have a ciliate leaflet margin although the buds, bark and leaves are typical of shagbark hickory. The minimum shell thickness observed for the side of the nut was 1/2 a millimeter (0.5 mm.) and the thickest was 2.0 millimeters. As previously stated, nut types B and D (the elliptical and obovate nut forms) were the easiest to crack. Nut type A was the most difficult and had generally the thickest shell.
The seed coat color range was from a light tan to a bronze color. The seed itself was in all cases sweet although certain of the nuts had a more pleasing taste than others. The nuts eventually became rancid though 3 years of storage in a heated room did not cause the bulk of the test samples to change in flavor. This is unlike the pecan which, stored in the same room with the hickory nuts, became rancid by the following year after collection.
Summary of Observations
The following observations concerning shagbark hickory may be made from this study:
(1) The buds of shagbark fall into 2 classes based on bud shape, (1) globose-ovate and (2) elliptical, the latter being the largest bud as a rule.
(2) The buds of shagbark fall into 2 classes based upon the length of the attenuated apex of the outer bud scales. The elliptical form of bud consistently had the longest drawn out apex.
(3) Normal buds of shagbark occur singly on the twigs above the lobed leaf scar; however, 2, 3 or 4 superposed buds may occur on very fast grown sprouts or terminal shoots of vigorously growing trees.
(4) The twigs of shagbark are pubescent but range in degrees from almost none to densely pubescent. The fastest grown twigs are apt to be the least pubescent.
(5) Leaves are compound with 3-5 leaflets commonly found and 7 leaflets rarely found.
(6) Leaflet shapes varied from tree to tree being ovate, obovate or elliptical.
(7) Leaflet margins with one exception were more or less ciliate.
(8) Most female flowers of shagbark have 2 stigmatic lobes, however, 3 stigmatic lobes resulting in triangular nuts are not uncommon.
(9) The typical male ament is three branched but one and two branched aments have been observed.
(10) The husk of shagbark varies in thickness from 1/8 inch to 1/2 inch in thickness when dry. The usual husk is 4-parted but one tree bore 5-parted husks consistently.
The average husk thickness is around 1/4 inch.
(12) There are three general fruit shapes, (1) globose, (2) ovoid and (3) obovate.
(13) There are at least 5 general types of normal nut shapes for
Onondaga County, N. Y. as listed in the text of this paper.
(14) Three abnormal nut types were also encountered growing
concurrently with the normal types.
(15) Nutshell color varied from brownish to creamy white. The darker colors were generally associated with the elliptical, oval or obovate nut forms.
(16) Nutshell thickness varied between 1/2 and 2 millimeters; the more angled the nut, the thicker the shell.
(17) All of the hickory nuts tested had sweet, edible seeds. The seed coats varied from a light tan to a bronze in color.
Conclusions
Within the single species of nut tree called shagbark hickory, Carya ovata (Mill.) K. Koch., in central New York, there exists a great degree of diversity. However, in spite of these differences, the examined sample trees may be placed without a question in their proper genus and species and the author would venture the opinion that the advisability of placing variety names on portions of the species is a doubtful and hazardous procedure until much more is known concerning the species than is known at present.
MR. PAPE: This paper is the result of the fact that some of us down in Indiana are losing 75 to 95 per cent of our hickory crop each year by the curculio, and what we are trying to do is work up a little interest with this paper, so at the conclusion of this we can get a discussion started and learn the experiences of other people. Maybe you will be able to help us down in Indiana.
The Control of the Hickory Weevil (Curculio caryae)
EDWARD W. PAPE, Marion, Indiana
It is our thought that if some effort were made to bring to this assembly, a digest of what has been done to control the Hickory weevil, we might arouse enough interest to carry on some experiments.
If, at the conclusion of this paper, we can get enough discussion, we will be able to avail ourselves of the knowledge and experiences of others who have made attempts to control this pest, it would be to our advantage.
The Pecan weevil of the south and the Hickory weevil are identical and we learn the following from the experiments carried out by G. F. Moznette, Bureau of Entomology, U.S.D.A.
Pecan weevil damage is of two types—(1) that resulting from attack before the shell-hardening period in July and August and causing all affected nuts to drop, and (2) that resulting from attack after kernel formation and usually causing the shuck of infested nuts to stick tight to the shell instead of opening normally. Weevil-injured nuts of the second type contain grubs which destroy the kernels, or they contain holes about one-eighth inch in diameter which mature grubs have bored and through which they escaped after destroying the kernels. The first type of damage often passes unnoticed and is due to the feeding of early emerging weevils, which puncture the immature nuts with their long lancelike beaks to feed on the juices within. Since all nuts punctured in this way before the shell-hardening period drop to the ground, the entire crop may be lost if weevils are abundant and the crop is light. Such damage may be heavy even when a large crop is attacked. The second type of damage is generally noticeable at harvest-time in October and November, and in seasons when large numbers of weevils have been present practically the entire crop may be wormy at harvest.
Since the weevils do not feed very much on the outer surface of developing pecan nuts, stomach poisons applied to trees have been of little practical value in control. In 1944, however, laboratory tests showed that DDT could kill the adults, and that it was worthy of field trial.
Field tests were made at Fort Valley, Georgia, with DDT and the conclusions drawn from these tests show that the effectiveness of two applications of DDT at the rate of 6 pounds of a 50-percent wettable powder to 100 gallons of water in reducing harvest infestations to 1 percent gives rise to the hope that this treatment, applied for several seasons, will eliminate a pecan weevil infestation in an orchard, or will reduce it to such an extent that spraying every year will not be necessary.
The time of the first application of DDT cannot be based on the time of the first drop of nuts, because other pecan insects also cause the nuts to drop during July and August. However, pecan growers who wish to make the effort can time the first application accurately by spreading a sheet on the ground beneath an infested tree and lightly jarring the branches to dislodge the weevils. When the weevils are disturbed they fall and "play possum" and can be easily collected. When a minimum of six weevils can be taken by jarring the branches on any one tree, it is time to make the first application.
While the above will probably give an indication as to what can be done, using DDT to control the Hickory weevil, for those who have large plantings and can afford the expensive spraying equipment necessary, it will be necessary to look farther for control methods for the small orchard, where expensive equipment is not feasible.
The following is part of a letter from Dr. C. C. Compton, Entomologist for the Julius Hyman and Company.
"It is our thought that since DIELDRIN is so highly toxic to Curculionids it might be possible to take advantage of the habits of this insect and control it by spraying the soil surface. The larval stage of this insect leaves the nuts and enters the soil sometime in the fall. It is believed that the larvae penetrate the soil rather deeply, to a depth of perhaps a foot or more and remain in the soil over winter. In the spring or early summer the larvae transform to adults and emerge to lay their eggs. In some regions at least the adults do not emerge until the second year after the larvae enter the ground.
It is our thought that if DIELDRIN was applied to the surface of the soil that many of the larvae would be killed upon entering the soil or would be killed at some later time when the adults emerge.
Dr. C. L. Fluke at the University of Wisconsin has been working for the past several years with DIELDRIN applied as an orchard spray for the control of plum curculio. In Dr. Fluke's work he applied the DIELDRIN to the orchard floor or cover. He has had some very promising results. Dr. Fluke has used two application rates, namely, six pounds and three pounds of DIELDRIN per acre. Since he obtained a high degree of control at the three pound level, it would seem worthwhile to investigate the possibilities of applying even a lower rate, say one and a half pounds per acre. In Dr. Fluke's work he applied the DIELDRIN to the soil in the orchard using a DIELDRIN emulsifiable concentrate containing one and a half pounds per gallon.
DIELDRIN is now available impregnated on a 30-60 mesh attapulgus clay. Such formulations are now available containing 5%, 10%, and 15% DIELDRIN. The DIELDRIN granules would appear to have certain advantages over liquid sprays where the grove has considerable ground cover. A high percentage of the insecticide is retained by the cover and does not reach the soil. The 30-60 mesh granules have the advantage of penetrating even the densest cover and their application results in a maximum deposit of the insecticide on the soil surface.
Groves or orchards under cultivation can be sprayed or treated with the granules. In either case it is advisable to disc the insecticide into the soil following application.
The granules are free flowing and can be applied quite readily with any fertilizer or distributor.
Without any field experience to go by it would seem that a 5% 30-60 mesh DIELDRIN granule formulation would be most convenient to use. By using a 5% DIELDRIN granule material you would obtain a dosage of 1-1/2 pound of actual DIELDRIN per acre by applying 30 pounds of granules per acre. Likewise, 60 pounds of the granules per acre would give a dosage of 3 pound of DIELDRIN. On the basis of work done with DIELDRIN for the control of the Japanese beetle, 3 pounds of DIELDRIN per acre will control this insect for more than 5 years. While it is not safe to assume that we could expect the same results in the case of the Hickory weevil, it does give us something to go by."
It seems likely that the foregoing will create some interest and that by the time of the next annual meeting we should have the results from the use of DIELDRIN to control the Hickory weevil.
MR. PAPE: It is my thought now if we could get a little discussion here concerning what some of you have been doing to control this pest, we might get somewhere, or at least get enough suggestions or get enough parties interested to carry on some experiments in different parts of the country.
MR. SILVIS: What company makes Dieldrin?
MR. PAPE: Julius Hyman Company is the one that sent the most literature and Shell Corporation local agents handle it. Also in Indiana the Farm Bureau Cooperative store handles it. The cost in small quantities is two pounds for 85 cents.
MR. KYHL: Is Dieldrin poison?
MR. PAPE: It's poison like all of these modern sprays, but it isn't as dangerous as Parathion.
MR. STOKE: In Virginia I have had no experience with DDT, except with chestnut, and it takes three sprays at two-week intervals to control the pest.
DR. GRAVES: What time of the year?
MR. STOKE: Apply the last spray about two weeks before the nuts ripen. That means, with us, starting in late July. You have to figure it for your own region.
MR. GRAVATT: There is literature available from the Bureau of Entomology in Washington on spraying to control pecan and chestnut weevils. They have done quite a bit of research on it.
MR. STOKE: If this ground treatment is effective, I'd like to try it.
It's a lot easier.
MR. PAPE: That would be very nice if you would repeat the work in
Virginia. I know that the Pecan Growers will work on the problem in the
South. If we could get work done in the Central States, it would be an
advantage for all of us.
MR. STOKE: In my area the control of the pest is complicated by the presence of the chinquapin.
PRESIDENT BEST: We have a surprise feature this afternoon. Dr. Graves of the Connecticut Experiment station, who, as you know, is the father of a lot of this work on chestnuts, has consented to discuss with us certain new procedures that he used in grafting chestnuts.
DR. GRAVES: We have worked with this method of inarching blighted chestnuts so long and found it so successful that I felt it my duty to tell you people something about it. It's really a method of cure for the blight on Oriental chestnuts and their hybrids. I have not found it to work well on the American chestnut.
Now, suppose we have our tree, with a blighted area on the trunk. I am assuming that the blight starts near the base of the tree as it usually does.
When you see it, you cut it out with a sharp knife removing the bark to the wood. Blighted trees send up shoots from the base, below the blighted bark. So you take one of these shoots, sharpen it at the top and insert this sharpened tip under the healthy bark at the top of the blighted area. The shoot should be a little longer than the blighted area so that you can get a spring to the shoot as you push its tip in between the bark and the trunk. Even if it goes up above and breaks the bark a little bit, it doesn't matter. This inarched shoot renews the connection between the leaves and the roots across the blighted area.
You know the leaves make the food of the tree, which goes down in the bark to the roots. The reason blight kills these trees is that it begins to girdle and sometimes does girdle the tree and destroys the connection between the leaves and the roots, so the roots eventually die. But by this method of inarching you restore that connection between leaves and roots.
Now, you'd be surprised to see how well that's worked with us. We tried it first in 1937. We have been doing it now for 16 years. Every spring we take our trees that show the blight, our hybrids and Oriental chestnuts, and inarch, and the whole thing doesn't take more than a few minutes. Then after our shoot is inarched here, we tie it with old-fashioned string. The tips of the inarched grafts should be covered with grafting wax or paraffin.
The scion will probably send out shoots which should be removed. And another thing, cut the string when you know the graft has taken above.
If the blighted area is higher up in the tree, you can use bridge graft. This, you can see, is a kind of bridge grafting. But in bridge grafting, the scion must be anchored in the bark both above and below the lesion.
As I say, we have cured our hybrids. There doesn't need to be anybody losing a Chinese chestnut tree ever, using this method. No sense in it. You can usually do this grafting in the spring about April when the leaves and the buds are beginning to show their green.
Any questions?
MR. DAVIDSON: You say you paint the wood?
DR. GRAVES: Yes, with any ordinary paint. There is a tree wood paint, I know, that's better, but we use ordinary paint.
Meeting adjourned at 4:50 o'clock, p.m.