Chapter X: Section X: Amendments to By-Laws (3)

______________________________________________________
| |
| HARVEST DATA |
|______________________________|
| |
| 1926 and 1935 Planting[3] |
Length |______________________________|
Date Harvest | |
Year Harvest Period | Yield No. Trees Av. Yield |
Began in Days | in Lbs. Bearing per Tree |
_______________________|______________________________|
| |
1932 | 14 3 4.7 |
1933 | 7 7 1.0 |
1934 | 80 16 5.0 |
1935 8-29 22 | 222 22 10.1 |
1936 8-26 33 | 379 25 15.1 |
1937 8-26 37 | 278 18 15.4 |
1938 8- 6 42 | 480 21 22.9 |
1939 8-15 42 | 995 26 38.3 |
1940 8-27 38 | 740 34 21.8 |
1941 8-14 51 | 1,467 38 38.6 |
1942 9- 3 41 | 876 32 27.4 |
1943 9- 9 26 | 1,335 38 25.1 |
1944 8-15 44 | 560 29 19.3 |
1945 8-18 34 | 1,450 27 53.7 |
1946 8-20 41 | 1,455 28 52.0 |
1947 8-26 43 | 1,975 27 73.1 |
_______________________|______________________________|

_______________________________________________________________
|
| HARVEST DATA
|_______________________________________
|
| 1938 and 1940 Planting[4]
Length |_______________________________________
Date Harvest |
Year Harvest Period | Yield No. Trees Av. Yield Range in
Began in Days | in Lbs. Bearing per Tree Yields
_______________________|_______________________________________
|
1941 8-14 51 | 44 63 .7 .1-6.9
1942 9- 3 41 | 30 46 .7 .1-5.2
1943 9- 9 26 | 357 108 3.3 .1-29.7
1944 8-15 44 | 716 136 5.3 .1-37.0
1945 8-18 34 | 3,025 208 14.6 .1-50.7
1946 8-20 41 | 1,447 173 8.4 .1-48.3
1947 8-26 43 | 6,615 188 35.2 .1-108.5
_______________________|_______________________________________

[Footnote 3: 28 trees planted in 1926 and 16 planted in 1935, at spacing of 25 to 40 feet.]

[Footnote 4: 274 trees planted in 1938 and 60 in 1940, at spacing of 25 feet on square.]

The yield's produced in the 1938 planting have been outstanding, as indicated by the data in Table I, The trees began bearing when younger and developed heavier production than those of the 1926 planting, whether judged by age of tree or years of bearing. Many of the trees have produced nuts of outstanding size, attractiveness, eating quality, and keeping quality. There has been the usual degree of variation common to any collection of seedlings, but the best trees in this planting have been superior to any previously seen. Nut size has varied from 23 to more than 100 to the pound; the color of the nuts has varied from light tan to deep mahogany, and a few are nearly black. All have been of good eating quality. The keeping quality has varied materially, some keeping very well and others quite poorly.

Bur opening, has likewise varied so that at one extreme the nuts drop entirely free from the burs on some trees and at the other extreme the burs drop with the nuts in them and considerable work is required to remove the nuts. It is out of this group of trees that the three seedlings have been selected that the U. S. Department of Agriculture is considering worthy of variety status. These have not yet been officially released and no official description is yet available. The yield data for these three selected Seedlings are given in Table II.

Table II. Yield data by years, of three seedlings tentatively proposed for variety status, Philema, Georgia.

------------------------------------------------------------------------- Tree Proposed Yield in Pounds by Years Total yield No. Nuts (in Lbs.) per Lb. --------------------------------------- No. Name 1941 1942 1943 1944 1945 1946 1947 1948 from Planting ------------------------------------------------------------------------- 7880[5]Meiling .2 3.6 20.9 36.9 23.9 73.1 36.9 195.5 38-43 7919 Kuling 4.0 3.8 5.8 6.5 13.8 34.2 50.2 38.2 168.5 35-43 7930 Nanking .1 3.8 28.0 37.8 1.0 87.7 54.6 213.0 30-43 -------------------------------------------------------------------------

[Footnote 5: Meiling ("Beauty") is the first name of Mme. Chiang Kai-shek.]

The trees of the "FP" designation and, of other species were grown to fruiting, but have since been removed or topworked in entirety because of their lack of desirable characteristics and because they produced pollen for cross-pollination which would result in undesirable progeny when the _Castanea mollissima_ nuts were used for seed. Furthermore, a number of trees of the three-letter designations have been removed or topworked because they produced very small nuts, or showed poor keeping quality, or because of some other undesirable characteristic. Therefore, the nuts now being produced in this experimental orchard are of pure _C. mollissima_ inheritance of the best type, and, as such, represent some of the best and purest seed nuts available in this country today. This procedure is being continued so as to maintain the quality of the nuts for seed purposes at its present standard.

Unfortunately, many of the nuts offered in the general trade for seed purposes at the present time are coming from orchards composed of a mixture of species or types comparable to the 1938 Philema planting before culling. This is very undesirable because of the great variability in the nuts produced by trees with such an origin. When grafted or budded trees of the newer and improved varieties are available to orchardists chestnut growing for nut production may be based on the same sound practices as the other fruit industries.

In the topworking of "FP" trees at Philema with scions from other strains of _Castanea mollissima_ the degree of incompatibility has been so great, that the scion tops will have either blown out or died at the end of four or five years from grafting. At the present time this failure can only be attributed to the fact that the stocks were of mixed ancestry. On the other hand, scions of pure _C. mollissima_ placed on the same stock strains have made good unions and are entirely normal after as long as 13 years from grafting. This problem of incompatibility between stock and scion is one that yet remains to be completely solved.

The topworking of trees in the five-acre block at Philema has been generally successful where incompatibility is not a problem. Bearing-size trees topworked one spring will generally produce a few nuts in the second subsequent growing-season. Growth the first year after grafting will frequently be as much as 12 feet long and very stocky. Both cleft grafting and inlay bark grafting have been practiced, the latter method proving to be the more satisfactory from all standpoints. In this method of grafting scaffold limbs from 1 to 6 inches in diameter are cut off square across. Scions 6 to 8 inches long are prepared by making a slanting cut 2 to 3 inches long and ending about three-fourths through the scion at its basal end. A strip of bark just wide and long enough to receive the scion, with about one-half of the upper end of the bevel showing above the cut surface of the stub, is then removed from the stub. The scion is then nailed into place with 5/8-inch nails and painted over with melted grafting wax. Two or three scions are required for most stubs. This work is done just as growth is starting in the spring and the bark is slipping well. The scions may generally be cut directly from the trees, but sometimes they may need to be cut several days earlier and stored in damp material in a refrigerator to keep them dormant.

In south Georgia the Chinese chestnut normally begins growth soon after March 1, but in some years it has started as much as a month after this date. Between south and north Georgia there is a differential in the time growth starts in the spring of one to two weeks. This differential also carries over into the date of blossoming and the date the harvest period begins. In south Georgia pollination generally occurs during the latter part of April and early part of May, and the harvest period begins about 100 days later. The peak of harvest averages 185 days after the initiation of growth in the spring. Dormancy comes only after the first frost sufficiently heavy to kill the leaves, usually about two months after nut harvest is completed. This period between harvest and leaf fall is undoubtedly an important factor in the annual bearing habit of the chestnut in the Southeast since it permits the food reserves in the tree to be replenished after the crop is mature. This is true under favorable conditions but does not hold under conditions of crowding, low soil fertility, or premature defoliation. For best growth and production the tree should be in foliage approximately nine months out of the year.

+ORCHARD MANAGEMENT+

The planting of chestnut trees in the Southeast should be done as soon as possible after the trees become dormant in the nursery. They should be planted on fertile soil which is well drained but not subject to serious drought injury. The Chinese chestnut cannot withstand a high water table, or free standing water, but appears to be somewhat resistant to drought injury when once well established. The chestnut trees have not yet reached an age at which their largest potential size has been attained, but trees of 50-foot spread have been observed. It appears likely, then, that orchards should be planted at 50 to 60-foot distances on the square, unless closer planting and subsequent thinning is resorted to in order to build up high nut production per acre at an earlier age of the orchard. Planting distances of 25 x 25 feet, 30 x 30 feet, 25 x 50 feet, and 30 x 60 feet are recommended for this reason, but only if the orchardist will plan to thin the stand at 10 to 15 years of orchard age and at later intervals as required. In no case should the branches of adjacent trees be allowed to touch as under such conditions competition between trees will reduce the yield per tree and nut size, and induce alternate-year bearing.

In planting the young tree it is usually advisable to fill the hole in which the tree is to be set with top soil, packing it firmly around the roots as the hole is being filled. Usually no fertilizer is used at the time of planting, although mixing about a handful of bone meal with the soil around the roots has given a higher percentage of living trees and has increased growth the first year. A shallow basin around the tree to facilitate watering when necessary during the first growing season, or the application of a mulch around the tree, or both, will be helpful in obtaining a high percentage of living trees and good growth. Adding water at the time of planting is good insurance that the soil will be well settled around the roots. A wrap of newspaper tied loosely around the trunk of the young tree will aid in preventing winter injury and sun-scald.

Under conditions of little or no care the seedling chestnut tree will generally develop several trunks as a result of the forcing of multiple sprouts from near the ground line. The tree should be trained to one trunk, as such a form seems to be less susceptible to winter injury while young and makes a much more desirable orchard tree when older. Pruning of the young trees subsequent to the development of the head at a 4 to 5-foot height should be confined to the removal of crossing branches and those so near to the ground as to interfere with the necessary cultivation and harvesting work under the tree.

Most soils in the Southeast are somewhat low in fertility and must receive good care if chestnuts are to grow well. The annual application of commercial fertilizers is generally required as is the growing of a winter green manure crop, preferably a legume. One of the most satisfactory systems is to plant hairy vetch, Austrian winter peas, or blue lupine[6] in late October or early November, applying broadcast at the time of planting from 400 to 600 pounds per acre of a 0-14-10 or 0-14-7 fertilizer mixture. This green manure crop should then be disced in by April 15 of the following spring, with subsequent shallow cultivations at about six-week intervals through the growing season. The ground should be clean by the middle of August to facilitate harvesting the nuts. If such a system of culture is not feasible, as on too steep slopes or around buildings, mowing or mulching can be used to advantage, but the trees must be given annual applications of a complete fertilizer mixture, such as 4-8-6, 6-8-8, or 5-7-5. These should be made each year about a month before growth starts at a rate of 2 to 3 pounds for each year of tree age. This should be broadcast under and slightly beyond the spread of the branches.

It has not yet been found necessary to spray the trees for the control of any disease or insect. This does not indicate that control measures may not be required at some time in the future, for it is the history of horticultural crops when planted in any concentration that diseases and insects increase in number and degree of injury. As yet, the chestnut weevil has not been found at the lower elevations in the Southeast.

In a few plantings a condition causing some premature defoliation has been observed at infrequent intervals. The condition begins as a leaf scorch which may or may not develop to the point where the leaf drops. It is thought to be caused by some mineral deficiency or unbalance associated with erratic weather conditions, but the exact cause is yet unknown. A leaf spot disease has been observed but has caused no appreciable defoliation and no control measures have been thought necessary.

[Footnote 6: Blue lupine is winter-hardy only in the warmer coastal areas, not adapted north of Columbus, Georgia, Meridian, Mississippi, or Shreveport, Louisiana. Ed.]

+Harvesting and Nut Storage+

Harvesting of Chinese chestnuts has proved to have definite requirements if the nuts are to be obtained in the best possible condition. The nuts are quite susceptible to rots of several kinds and must be properly handled to keep losses at a minimum. They are also very easily and quickly injured by exposure to the sun, with the consequent, high temperatures and drying. If the nuts are to be stored for any length of time, as is necessary when they are to be used for seed purposes and as will be necessary when they are to be marketed for eating purposes during the Thanksgiving and Christmas holiday seasons, it is paramount that they be picked up from the orchard at not more than two-day intervals. Cleaning up all dropped nuts at daily intervals is most desirable.

At the end of each day the harvested nuts must be placed in cold storage at temperatures between 32 deg.F. and 45 deg.F. It has been found that a nearly air-tight container is required in order to maintain a relative humidity of 100% and prevent too much drying of the nuts. A 50-pound tin lard can with one 20d nail hole in the side near the lid has proven to be a good container for large quantities and these same cans also make good shipping containers merely by wiring on the lids. One-gallon friction top syrup cans with a single nail hole in the side make a good container for smaller quantities. In air-tight containers the nuts do not decay but germination capacity is quickly destroyed and bitter flavors develop quite rapidly. Nuts to be used for eating purposes shortly after harvest may be stored at lower relative humidities but should be placed in cold storage. A loss of about 15% in weight from the fresh weight of nuts is necessary to reach proper eating quality. Nuts dried to this extent are sweet and palatable but cannot be stored for any length of time and fail to germinate well when planted.

The experimental study of chestnut storage problems is being continued with the hope of working out still better methods. The manner of marketing chestnuts so that they will reach the consumer in a desirable condition also is still to be worked out, but it appears possible that retail cold storage and packaging in moisture-proof bags which are pervious to CO_{2} and O_{2} give promise at present. Probably the most promising aid to an increased storage life of chestnuts will come through the selection of trees for propagation and planting that produce nuts of superior resistance to storage rots. There is rather great variation among seedlings in this respect, some being-quite superior, although no completely resistant seedlings have yet been found.

+Discussion and Conclusions+

The perishable nature of the nuts of the Chinese chestnut has probably been the greatest drawback to an earlier acceptance of this crop as an adjunct to the horticulture of the Southeast. It has been only in the past few years that enough has been learned about the harvesting and storage requirements to permit the storing of these chestnuts so that they can be marketed in an orderly manner either for eating or for seed purposes. Storage losses through periods up to six months have been held to less than 10% for a mixture of nuts from all the trees at Philema. Storage tests of nuts from individual trees have shown a range in keeping quality from no loss after six months' storage to nearly 100% loss. By culling out the trees producing nuts with a high rate of spoilage under the best storage conditions it should be possible to reduce storage losses to a minimum. Every grower of seedling trees should follow this same process of culling out or topworking trees producing nuts of poor keeping quality if the industry is to grow and prosper, since otherwise the offering of spoiled nuts for sale to the consumer will soon destroy the demand for the nuts.

There is no question but that the Chinese chestnut tree is very well adapted to the Southeast. It has proven to be healthy, vigorous, and productive. Yield records at Philema show actual yields of more than 1,000 pounds per acre and potential average annual yields of 1,500 or more pounds per acre are not out of reason. In 1947, in the Brown tract at Philema, if all the trees that bore nuts had been collected into a solid block the yield per acre would have been nearly 2,500 pounds. Crowding of the trees in the Brown tract is becoming serious at 11 years of age with a 25 x 25 foot spacing. Alternate-year bearing is becoming apparent and the stand of trees must be thinned immediately. Because of such potential yields and because rather extended storage of nuts of varied keeping quality is now economically possible the future of the chestnut industry in the Southeast is very promising.

The selection and propagation of selected seedlings is desirable as a means of advancing the industry at a more rapid rate. The propagation of selected seedlings offers a problem because of lack of compatibility between some stocks and scions. Since the chestnut is almost completely cross-pollinated it may be necessary to develop special plantings of two or three selections as a source of seed nuts for the production of stocks. Such plantings might possibly produce seedlings of quite uniform and desirable characteristics, but this prospect, is not very promising. Certainly, the evidence points to the conclusion that scion selections must be worked on stocks of the same strains if incompatibility is to be held at a minimum.

There is a further problem in the propagation of varieties on seedling rootstocks in the nursery. Only one propagator appears to be having much success in this art but others must learn it. Topworking of older trees by the inlay bark graft is generally successful and older seedling orchards can be worked over to improved selections without difficulty so long as the stocks are of compatible strains. Time will be required to work out the details of the solution for this problem but they will be worked out.

In the selection of improved seedlings for propagation the strictest attention should be paid to the important characteristics of tree vigor, precocity, productiveness, nut size, attractiveness, and keeping and eating quality, and type of bur opening. These characteristics have been previously discussed but it is well to emphasise their importance. The tree that comes into bearing at an early age seems likely to be more productive in later years. The nuts should be no smaller than 45 nuts to the pound and be attractive to the eye of the buyer. Most individuals prefer nuts with a bright and shining surface free of fuzz and with a fairly rich mahogany or chocolate color. Keeping quality is, of course, of great importance and should be carefully determined. Eating quality is generally good but distinctly superior selections may be found in the future. For the most part eating quality is dependent on the proper curing of the nuts. The type of bur opening is more important than usually considered, as it materially affects the satisfactory harvesting of the nuts. From the commercial standpoint it appears that the most desirable bur should drop from the tree with the nuts still in it but be well split so that the nuts can be readily removed. Such a bur type prevents exposure of the enclosed nuts to the hot sun while on the tree and reduces injurious drying to a minimum yet permits rapid gathering of the nuts in the burs for later mechanical separation. Nuts that drop free from the burs are more subject to injury by drying and require more hand work in gathering. Burs that do not split readily would be more difficult to separate mechanically; and mechanical aids will be necessary for the economical daily gathering of the nuts in commercial orchards.

If is encouraging to note that many of the present new plantings in the Southeast are being made by orchardists rather than hobbyists. Many home owners are planting a few trees but the acceptance of the Chinese chestnut for commercial production by men already growing other orchard crops portends the future success of the industry. The hobbyist has been of great service and should be given full credit for his far-sighted interest in a crop that now has commercial promise, especially in the Southeast. Much experimental work is still needed by both State and Federal agencies and by individuals. This work needs be concerned now more with details of refinement rather than with basic possibilities of the crop.

* * * * *

President Davidson: Mr. Carroll D. Bush, of whom I am sure you have often heard and whom very few of you, including myself, have met, of Grapeview, Washington, will now tell us something about the Marketing of Chestnuts on the Pacific Coast. Mr. Bush.

Marketing Chestnuts on the Pacific Coast

CARROLL D. BUSH, Grapeview, Washington

Mr. Bush: Friends of the Association: There are so many here that I have known through correspondence that I have welcomed this opportunity to say something to you today. I don't think that I will add very much to anything that has been said. I hope perhaps we will have some ideas from what we have been doing on the Coast.

We were in the nursery business near Portland, and during the war we went out of it, but we are working back in trees again[7], and all this time we have been preaching the gospel of nut trees, and we find that we can't preach a gospel unless there is some reward. There is no market for chestnuts in our section of the country, and yet we had quite a few of them around Portland. We could not talk about chestnut trees when there was no market. Buyers there had been offering as low as three cents a pound or not buying them at all, and we, ourselves, had quite a few nuts to sell. So I took a trip up to Seattle and found a commission man there that would take our nuts and arranged with him, and we have sent nuts to Seattle ever since that year and got a very good price. Then a neighbor had me send some of his, and we are still sending nuts.

+Introduced on Mid-West Markets+

The next year through Carl Weschcke of St. Paul I got in touch with a reliable Minneapolis firm. They evidently had been burned and they were somewhat skeptical. They said if we would send a sample there they would look them over. So I went out and picked up a mixed sample and shipped to Minneapolis, and they said if we could send nuts as good as the sample they could use some.

We began to send them. When we shipped them we made sure we sent nuts that were considerably better than the sample, and the rewards for shipping there were also very good. Then we went on to Chicago, and we have been shipping to Chicago over since. At this time I am out here to find a little more market for some of the nuts that we have in Oregon.

At first we put the nuts in cold storage at about 32 degrees, expecting to get a better price on the Thanksgiving market. We found out that we were making a mistake and that the earliest nuts on the market brought us our best price. So now we are shipping just as early as we can ship.

We first adopted the western cranberry box as being open enough to allow a little drying off and tight enough so that it wouldn't allow too much and yet we didn't get any mold. We were very much afraid of that, because a good many of the California chestnuts had molded on the way to market. Later we turned to the splint bushel basket, and lately we have been in favor of the half-bushel basket. There seem to be buyers who don't like to stock up more than a half bushel at a time, chestnuts being of a rather high price. They dry out too fast.

We found that cold storage above 32 degrees keeps chestnuts in good condition with little dry-out. One dealer in Oregon we know of wraps his cold storage nuts in waterproof paper, keeps them that way clear on into January. A very little mold will develop on chestnuts kept in storage from 32 to 35 degrees, but not enough so we take any precaution. We have had a few batches that people have stood in sacks on damp nights, and they started to mold, especially on the open end, and we find we can kill the mold with Clorox. We have just used a little Clorox in water. We think this would prevent mold from developing on all nuts if they were put through a chlorine bath. We haven't taken the trouble to do that. I might say our walnuts, and filberts have been put through a chlorine solution, and, of course, after a chlorine solution is used you have to put the nuts through water again and wash that off.

We have on our place a nice washer. We have graded the European varieties, which we handle mostly, into three grades: standard, fancy, and extra fancy, by size. All our grading has been done by hand, except we expect to have a simple grader this year.

[Footnote 7: Mr. Bush informed the secretary by letter, early in 1949, that he did not then have any nursery stock ready for sale at his Eagle Creek, Oregon, nursery. From that location about 10 years ago he introduced, under numbers, three selections of Chinese chestnuts grown from seed imported in the early 30's. Two of these, in 1941, were named Abundance and Honan. The Abundance is now considered one of the most desirable varieties from Oklahoma to Pennsylvania, while Honan is slightly less desirable.--Ed.]

+"Sweet" Nuts Sell Faster+

We have a few "sweets." All of those on our farms are Riehl varieties, hybrids, I think. All of our European chestnuts have an astringent pellicle, heavy with tannic acid. We classify as sweets any of those that have a pellicle that is sweet enough to be eaten. We label these the sweets and mark them as they go into the market. And while, I say, we don't seem to get a better price for the sweets than for the European, they do sell faster. There are some people in the eastern cities that are grabbing these in preference to the large ones. While the large nuts sell very well, I suppose they go to the Italians and Europeans who are used to cooking them, and out on the West Coast nothing but the large nut goes; the larger the better. In the Seattle market we try to send in large nuts.

We also grade out all "cracks" by hand. They mold easily, and we have a lot of cracked nuts in our climate there, but we have been able to dispose of all of these through the Seattle market where they move off very fast and are lower priced.

+California Supplies Distant Markets+

Last winter we went to California and looked into the chestnut market there. We found them in the Sierras and found them growing in the Coast Range without irrigation, but the largest growers were in the San Joaquin Valley near Stockton. The largest grove was 30 acres at Linden owned by Caesar De Martini. He gave us our best insight into California chestnut growing. He used to grade and package his own, and he still has his cylinder grader. It has three different size holes, one inch, one and a quarter and one and a half. Anything that goes through the one-inch hole is discarded as a cull. That leaves three sizes, the size that goes through the one and a quarter, the one and a half, and the size that goes out the end, which is, of course, a class of jumbos.

All the chestnuts in California, I think, now go to buyers to do the grading and packing much as De Martini worked out. All of the California nuts have to be soaked in water just as Mr. Jones does, as they come to the packer dried out. The largest buyer that we found in California shipped about seven carloads, and he shipped them all over the world, the Philippines, Honolulu, Alaska, and other places where the chestnut hasn't been growing.

+Early Autumn Best Marketing Season+

Now, I am going to sum up what our experience has been and what we recommend as general from our experience. Your experience may be different. We clean the nuts, wash them, if necessary, grade them; large and small nuts do not sell well together. We would pack in baskets, half bushel for sweets. We are trying to make that half bushel basket the mark of the sweet nut in the markets where we sell, so that when a buyer comes in there and sees a half bushel basket he knows that's sweets. Then we ship as wet as possible, and they dry out on the way. And just as fast as we can get those nuts off the ground we pack them and ship them. Our greatest trouble now is, of course, the imported chestnut. They are beginning to come in in great quantities, and they hit the market in Chicago last year at about the 20th of October, and we tried to beat that line if we possibly can with our nuts, because just the minute the carloads of chestnuts come in on the East Coast the market drops right down.

Without question we could use some of the preparations that we use on filberts to put a gloss on the chestnut, run them through, I think it is a paraffin mixture, put a gloss on the shell and give us a better chestnut in the market, make it look nicer and, of course, make it sell better.

+"Stick-tight" Burs Preferred for Pacific Coast+

I disagree, I think, with two of the former speakers in regard to the chestnut that falls free from the bur. I would prefer a chestnut that sticks tight to the bur. We have threshers out there that thresh them out. We can pick up those nuts in the bur with a shovel or fork, throw them into the wagon, take them in the wagon, thresh them out. You have a cleaner nut, you don't have to pick around on the ground with rubber gloves that we use, which is easy enough, but it certainly adds a great deal of work as compared to threshing them out easily after they are once picked up.

I thank you.

* * * * *

President Davidson: Thank you, Mr. Bush. We are glad to have that western angle. It is going to be very useful to us.

Next on the program is a paper on the Control of the Chestnut Weevil, the author of which is absent, but I believe Mr. Gravatt is going to read that.

Chestnut Weevils and Their Control with DDT

E. R. VAN LEEUWEN

United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine, Division of Fruit Insect Investigations.

Failure of the American chestnut to resist the chestnut blight has resulted in the planting of a few blight-resistant species obtained from foreign lands. These foreign chestnuts would now be planted more extensively in certain districts, were it not for the fact that the nuts are injured by two species of weevils, for which heretofore there has been no practical control.

The 1947 season marks the fourth year of the experimental use of DDT for control of the chestnut weevils. During these years our knowledge of the spray and how best to use it has been advanced by conducting laboratory and field tests. Unfortunately, few chestnut orchards now exist in the Eastern States, and the scattered plantings consist mostly of a large number of Asiatic seedlings, some of which had to be top-worked to other Asiatic species and varieties. Many of these trees are grown for ornamental, shade, or timber purposes rather than for nut production. Owing to these conditions and to a series of spring frosts since 1945, it has been impossible to conduct insecticide experiments on an adequate basis of replicated plats.

Although much is to be learned regarding time of application of the sprays and the proper dosage, the use of DDT can be recommended as a standard practice, because it has proved highly valuable in protecting chestnut trees from heavy losses due to the chestnut weevil. It is the purpose of this paper to discuss some of the experiments that have been made with DDT and the observations made on the time of egg deposition.

+Nature and Extent of Injury+

The worms attacking chestnuts are the larvae of two very similar species of weevils, one larger than the other. The adults are medium-sized beetles having extremely long, slender beaks. With these they drill through the husk of the nuts, making openings through which they insert their eggs into the nuts. From these eggs the familiar worms develop. Weevil injury varies greatly in different chestnut-growing localities. It is not unusual for 50 to 75 percent of the nuts to be wormy, and often infestation reaches 90 to 100 per cent. The small weevil does the most damage, but there are indications that this may not always be true. Because the mouth parts of the adult are situated at the end of an extremely long and slender beak, it can obtain most of its food from beneath the surface of the host plant. For this reason, stomach poisons applied to trees have not been eaten by these weevils, and hence have been of no practical value. As DDT kills by contact, it is necessary only for the body of the insect to come in contact with DDT.

+Life Histories of the Weevils+

In the vicinity of Beltsville, Md., the adults of the large chestnut weevil[8] leave the soil about August 15. The date will vary, of course, with season and locality. Both males and females soon begin to feed by piercing the burs with their long beaks. Mating begins soon after the weevils collect on the trees, and egg laying follows shortly. The eggs hatch within a few days and the worms develop within the nut. A few of the worms will complete their growth and leave before the nuts fall, but most of them emerge from the nuts after they have fallen. The worms then enter the soil, where they build cells and remain until they change to pupae the following summer. This weevil has a one-year cycle, or one generation a year.

The life history of the small chestnut weevil[9] is somewhat similar, except that in the vicinity of Beltsville the weevils leave the soil late in May or early in June, when the trees are in bloom. Several weeks later the females deposit eggs in the nuts. At Beltsville, egg laying begins late in August and continues for several weeks. After the nuts have fallen from the tree, the full-grown larvae leave them and enter the soil. Earthen cells are constructed at a depth of 4 to 12 inches, where some of the larvae remain for two winters.

The small chestnut weevil completes its life cycle in two years, and a small percentage requires three years, whereas the large chestnut weevil completes its transformation from egg to adult in one year. The large weevils pass the winter as larvae, whereas the small weevils pass one winter as larvae and the second winter as adults. With the few individuals of the small weevil which require three years for transformation, the first two winters are passed in the ground as larvae and the third in the same location as adults. This habit of the small weevil complicates control measures, as one season's spraying with DDT does not reduce the entire infestation of weevils.

[Footnote 8: +Curculio proboscideus+ Fab.]

+Proper Time for Spray Applications+

Application of DDT sprays at the proper time is very important. An examination in 1944 of many unopened chestnut burs disclosed the fact that eggs of the small chestnut weevil were being deposited many weeks before the burs would open. It was also noted that great numbers of the larvae were leaving the nuts soon after the burs cracked open. Evidently these full-grown larvae had hatched from eggs deposited several weeks before the burs split.

In 1945, 1946, and 1947, cloth bags were tied over developing burs at various intervals during the season to prevent further egg laying in the nuts. At harvest time, the bags were removed and the nuts examined. Occasionally adults were hidden among the spines of the burs and were inadvertently enclosed in the bags; therefore, all nuts in bags containing female adults that might have continued ovipositing were discarded. The data in Table 1 show the approximate time prior to which the nuts were infested.

Because of difficulty in obtaining sufficient burs for bagging, and other orchard conditions, the results of these studies were far from conclusive. They indicated, however, that many eggs had been deposited in the nuts before the burs had reached maturity. They also suggested that the seasonal histories of the two species are closely parallel. At Glenn Dale, Md., and Fairfax, Va., the small weevils predominated, constituting about 69 to 90 per cent of the total numbers taken. At Elkton, Md., only 42 per cent of the weevils were of the small species.

[Footnote 9: Curculio auriger Casey.]

Table 1. Results of studies to determine the time of oviposition of the
chestnut weevils.

Nuts Infested with

Date of Total Small Large Wormy
Bagging Nuts Chestnut Chestnut Nuts
Nuts Bagged Weevil Weevil
Year and Orchard
Number Number Number Percent
1945 July 9 52 2 5 13
Glenn Dale, Md. Aug. 1 46 4 2 13
Aug. 15 107 18 11 27
Fairfax, Va. Aug. 21 110 22 13 32
Sept. 12 123 63 11 60
1946 July 12 65 0 0
Glenn Dale, Md. July 18 40 0 0
July 26 67 0 0
Aug. 1 71 0 0
Aug. 9 29 1 0 3
Aug. 14 88 3 2 6
Aug. 23 53 18 2 38
Aug. 29 53 23 11 64
Fairfax, Va. July 26 98 0 0 0
Aug. 15 168 0 0 0
Sept. 4 164 139 16 95
1947 Aug. 15 54 5 1 11
Glenn Dale, Md. Aug. 25 38 8 0 21
Sept. 2 24 7 1 33
Sept. 9 42 18 4 52
Sept. 15 56 29 7 64
Sept. 22 90 27 11 64
Sept. 29 143 83 22 73
Fairfax, Va. Aug. 26 35 9 1 29
Sept. 10 58 25 4 50
Sept. 28 50 35 7 84
Oct. 7 217 177 22 92
Elkton, Md. Aug. 21 139 11 13 17
Sept. 4 83 22 25 57
Sept. 18 116 21 35 48
Oct. 1 108 31 44 69

+Spray Experiments in 1944+

Shortly after adults of the large chestnut weevil first appeared in the orchards in 1944, six trees isolated from other chestnuts were selected for treatment. Five trees were sprayed with from 1 to 5 pounds of technical DDT plus 1/2 pound of sodium lauryl sulfate to 100 gallons of water, and the sixth tree was left untreated as a check. A thorough application of a coarse, drenching spray at a pressure of 400 pounds per square inch was used in an attempt to force the DDT between the many spines of the burs. The DDT used was very coarse, and difficulty was experienced in getting a proper suspension. This formula was used, however, in preference to one which contained other ingredients that might have formed a protective coating over the particles of DDT. Heavy rains prevented later spray applications.

Adult weevils obtained by jarring untreated trees were then confined in screen cages placed over the lower branches of the trees. At the end of each cage was a cloth sleeve which was tied to the limb to hold the cage in place. The treatments used and the results are given in Table 2.

Table 2. Percentage mortality of chestnut weevils placed in field cages on trees at different intervals after they had been sprayed with with DDT, 1944.

Strength of
DDT (lb. per Small Chestnut Weevil Large Chestnut Weevil
100 gal.) 48 Hrs. 96 Hrs. 144 Hrs. 48 Hrs. 96 Hrs. 144 Hrs.

1 0 61 100 25 50 100
2 19 69 100 0 34 100
3 4 50 100 0 40 100
4 27 87 100 0 50 100
5 18 50 100 30 46 100
Check 0 0 0 0 7 7

Although the results obtained the first few days in the cages containing treated foliage were somewhat irregular, because of the small numbers of tests made, all weevils were killed within 6 days. The results indicate definitely that DDT is toxic to the adults of both species of weevils. No consistent differences between species were noted.

As the matured nuts dropped from the treated trees, daily collections were made, and one-third of each collection was used as a sample in determining the percentage of wormy nuts. At the time the nuts drop, the holes in the shell through which the eggs were inserted are very difficult to detect. The nuts were therefore held in wire baskets to permit most of the larvae to emerge before the final examination. All nuts not showing exit holes were cut open to find out whether they were wormy. The marked increase in clean nuts after all treatments indicates that DDT is a promising insecticide for use against the weevils. The treatment and infestation records for the sprayed trees and the check tree are given in Table 3, which also includes the results obtained in later years.

+Spray Experiments 1945 to 1947+

Spring frosts in 1945 destroyed 95 per cent of the crop of chestnuts in the Eastern States. Only six trees of different species and ages in the Government orchard at Glenn Dale, had sufficient nuts for experimental purposes. Applications of a 50 per cent DDT wettable powder in the proportions of 4 and 6 pounds plus 1/2 gallon of summer oil as a sticker to 100 gallons of water were made on August 20 and September 9.

Spring frosts again damaged the orchards in 1946, destroying about 80 per cent of the possible chestnut crop, and leaving only eight trees in the Government orchard that were suitable for experimental purposes. The remaining trees having a small scattered crop were disregarded. A mixture consisting of equal parts by weight of DDT and kaolin 41 was used in the strength of 2 pounds of DDT to 100 gallons of water. The time and number of applications were varied.

Table 3. Results of spray tests with DDT against chestnut weevils, 1944-1947.

Larvae Emerging from Sample
Reduction
Nuts Small Large Wormy of
DDT (per Application in Chestnut Chestnut Nuts Injured
100 gal.) Sample Weevil Weevil Nuts
Year
Pounds Number Number Number Percent Percent

Government Orchard, Glenn Dale, Md.

1944 1 Aug. 14 533 1896 21 44 42
2 646 402 45 25 67
3 712 421 5 18 76
4 951 814 5 22 71
5 1844 850 10 16 79
0 976 3238 100 76
1945 2 Aug. 20 & Sept. 9 660 434 38 30 57
3 305 285 58 22 69
0 297 1164 61 70
1946 2 Aug. 15 & 30, Sept. 11 621 131 12 9 90
2 Aug. 15 & 30 371 171 23 19 79
2 Aug. 30 & Sept. 11 292 87 21 26 71
2 Aug. 15 & Sept. 11 949 553 190 43 53
2 Aug. 30 1267 1407 98 43 53
2 Aug. 15 1212 3207 66 43 53
2 Sept. 11 368 1832 53 58 36
0 870 5364 134 91
1947 2 Aug. 13 & 29, Sept. 12 4084 3817 234 30 66
2 Aug. 13 & 29 2618 4255 151 52 40
2 Sept. 12 3029 9498 402 79 9
2 Aug. 13 2639 5049 198 51 41
0 974 4714 121 87

Van Reynolds Orchard, Elkton, Md.

1947 2 Aug. 21, Sept. 4 & 18 1153 264 64 14 84
2 Sept. 4 & 18 338 5 118 67 23
2 Aug. 21 & Sept. 18 149 18 59 34 61
2 Aug. 21 & Sept. 4 669 102 12 51 41
2 Sept. 18 324 63 129 77 11
2 Sept. 4 270 303 67 56 36
2 Aug. 21 500 192 127 57 34
0 338 152 118 87

Sprays containing DDT were applied in two orchards in 1947, the Government orchard at Glenn Dale, and the Van Reynolds orchard at Elkton, Md. Spring frosts injured 50 per cent of the chestnut crop at Glenn Dale and 70 per cent at Elkton, and as a result only a few trees suitable for tests were available. The remaining trees were not sprayed. Four pounds of the standard mixture of equal parts of DDT and kaolin were used to 100 gallons of water in all applications.

In Table 3 will be found information on the quantities of DDT used, the schedules followed, and the results obtained during the period 1944 through 1947.

These results indicate clearly the effectiveness of DDT in chestnut weevil control, in spite of numerous discrepancies brought about by the small number and variability of the trees available for the tests. As might be expected, programs of three applications were more effective than those of only one or two. Of the single applications, those put on during the latter half of August were much more effective than those made during the first half of September, presumably because most of the eggs had been laid by the early part of September.

These experiments gave fairly exact information on the relative abundance of the two species of weevils. At Glenn Dale the small chestnut weevil constituted 92 to 98 per cent of the population; at Elkton, 61 per cent.

The matured nuts that fell from count trees were collected daily, and one-third of each lot collected was used as a sample for determining the percentage of wormy nuts. It was possible, therefore, to obtain a rough estimate of the numbers of larvae produced on each tree. In 1946, from 1,863 nuts on a tree sprayed three times, 429 larvae emerged; and from a comparable unsprayed tree having 2,610 nuts 16,494 larvae emerged. In 1947, 1,350 larvae were produced on 9 trees with an average crop of 1,361 nuts sprayed three times, compared with 14,505 larvae from 2,922 nuts on an unsprayed tree. These figures indicate that DDT sprays bring about large decreases in the numbers of weevils and that the proper use of DDT sprays on all host trees over a period of a few years would doubtless reduce the infestation to a point where fewer applications would be necessary for effective control of the chestnut weevils.

+Tentative Recommendations+

For the benefit of those who wish to try DDT for chestnut weevil control, the following tentative recommendation is made:

Thoroughly apply +to all parts of the tree+ 2 pounds of DDT in 100 gallons of water. For example, use 4 pounds of a wettable powder that contains 50 per cent of DDT, or 8 pounds of one that contains 25 per cent of DDT. Make three applications, the first about 30 days before the first nut is due to drop, and the second and third after intervals of 12 days. Unless the entire bur, especially that portion near the stem end where most of the feeding punctures are made, +is thoroughly covered+ with a film of DDT, the weevils may feed without being affected by the insecticide. In handling DDT, one should use the same care as with such well-known poisons as lead arsenate, Paris green, calcium arsenate, and nicotine.

* * * * *

Mr. Gravatt: I might say that Mr. Van Leeuwen has used only a small section of our experimental orchard, and right near-by would be large sections not used. The weevils are not killed quickly by the DDT, they are somewhat resistant, and so we think quite a number of weevils come over and deposit eggs before they are killed by this DDT, because they don't lose any time getting to work on the nuts. He hopes to have much better results where the entire orchard is sprayed. This year we sprayed our entire orchard twice, and it is a real pleasure to go out there now and gather up nuts and not be eating weevils when we do eat them.

President Davidson: Well, Mr. Gravatt will now give us a talk on Diseases Affecting the Success of Tree Crop Plantings, and I am sure we all are on our toes to hear about that. Mr. Gravatt.

Mr. Gravatt: I only ask a few minutes to show a few slides.

(Slides shown.)

Diseases Affecting the Success of Tree Crop Plantings

G. F. GRAVATT and DONALD C. STOUT

Division of Forest Pathology, Plant Industry Station, Beltsville, Maryland.

Mass plantings of many trees of the same kind frequently result in an increase in the severity of insect pests and diseases. Leaf diseases, for instance, spread quickly through such plantings when weather conditions favor growth of the causal organisms. Plants on sites unfavorable to a specific tree species also are responsible for disease increases. Chinese chestnuts grown on a site where they are subject to early-fall and late-spring frosts will fail. Not only will crops be reduced by the killing of buds or blooms, but the twigs, or even whole trees, may be killed by freezing. The blight fungus develops rapidly on such injured trees and may mislead people into thinking that the blight fungus is the primary cause of the killing.

Still another factor that determines the damage by diseases, and thus the success or failure of nut tree plantings, is the ignoring of soil and fertilizer requirements. Trees weakened by drought, because they are on a site having a soil too shallow for good root growth, are much more subject to attack even by weakly parasitic fungi than those growing on a site with deeper soil. Innumerable dying twigs and branches with fungi growing on them are sent to the U. S. Department of Agriculture or State experiment stations with requests that the disease be identified, when the real trouble is lack of water for the roots. Weak trees are much more subject to winter injury than vigorous ones.

Trees require a good supply of plant food materials and water to produce profitable crops. Tho heaviest bearing chestnut trees we have observed were grown in an irrigated orchard in California and in a poultry yard in the East where chicken droppings actually formed a mulch under the trees. However, if you wish to kill a young chestnut tree quickly, just apply a very heavy application of chicken manure; the point is that trees must become adjusted to chicken manure by gradual applications.