Since the Japanese beetle is here to stay, and to spread, these differences are worth considering where plant materials are being selected for new ornamental plantings. In our bulletin on Japanese beetle (Cornell Extension Bulletin 770) we have to warn the reader that planting chestnuts may bring him trouble with the Japanese beetle, trouble which he would not have with flowering dogwood, ~Cornus florida~, or the common lilacs, ~Syringa vulgaris~, which are immune to this pest.
It may be, however, that some of the chestnuts carry immunity factors. In the U. S. Department of Agriculture Circular No. 547, published in 1940, "Feeding Habits of the Japanese Beetle," by I. M. Hawley and F. W. Metzger, ~Castanea crenata~, the Japanese chestnut, is listed with beech and chestnut oak as "generally lightly injured." I understand you consider the nut of this species poor, but if resistance factors are in the genus, there can be hope of finding or developing a chestnut resistant to Japanese beetle.
We might be able to do with chestnuts what has been done with poplars. The common poplars range from the Lombardy, ~Populus nigra italica~, which is heavily damaged by the beetle, to the white, ~P. alba~, which is immune. The forest geneticist, E. J. Schreiner, has written an article, "Poplars can be bred to order," which appears on pages 153 to 157 in "Trees," the Yearbook of Agriculture for 1949, published by the U. S. Department of Agriculture. Schreiner provides an interesting diagram of random planting of 102 poplar hybrids, in plots of 50 trees each, representing 30 parentages. He writes, "Japanese beetle infestation was heavy in ~1947~; as late as September 9 beetles were as numerous as 10 to 12 per leaf on the most susceptible plants. Although the insects were feeding everywhere on the sparsely scattered weeds growing under the hybrids, beetle feeding was found on only nine hybrids, representing four parentages. Three of these parentages include hybrids that were entirely free of beetle feeding during the entire infestation." Among five hybrids of ~P. charkowiensis~ and ~P. caudina~, three were highly susceptible, one moderately susceptible and one was non-susceptible.
Japanese beetles, when infesting rows of plants of the same variety, usually occur unevenly on the individual plants. Some of the factors have to do with the vigor or color of the tree. In my observation on peach, I have repeatedly seen a sickly, yellow and half-wilted tree with thousands of beetles in it, while other similar but healthy trees in the same row averaged only a few hundred beetles. You can make one branch of a tree more attractive to the insects than the rest of the branches by partly girdling it or permitting borers or cankers to damage the base of the branch. This observation suggests that the increased sugar content raises the attractiveness of the leaf. It coincides with what is already known that extracts of plants preferred by the Japanese beetle have, in general, a higher sugar content, or more of a fruit-like odor than those not attacked. (Metzger et al, Jour. Agric. Research, ~49~ (11): 1001-1008. 1934. Washington, D. C.)
There are other observations you can easily make yourselves. The Japanese beetle avoids shade, except on the hottest days, and its feeding in dense trees shows up most in the tops; its feeding on uniform plantings tends to show up most in the edge rows. Nursery-size trees are more extensively defoliated than larger ones. At this point we must consider that the insect usually has to fly into a planting from the outside, for it breeds chiefly in lawns and meadows. If the foliage mass of the nut planting is small and the grass areas nearby are large, the beetles are likely to do heavier damage than where the planting is very large and grass areas negligible. A small planting in a suburban area, beside a large golf course, cemetery or dairy farm, is going to be more heavily attacked than a large one set in a clearing in the woods.
~Control of the adult:~ The safest, most direct measure is to pick or knock the beetles off the plants, preferably in the early morning, when they are cool. They may be dropped in a pail with a little kerosene in it. Some plants can be shielded with thin nets which can be placed on them by day. We do not recommend Japanese beetle traps. These yellow traps, which are baited with geranoil and other essential oils, can draw beetles in from a considerable distance but we have found that, possibly because many beetles miss the trap, the population of beetles remains high near the trap, in spite of heavy daily catches. Although the use of one trap to the acre on a block 10 miles square would probably get results, the use of a few traps on a small nut planting is likely to be disappointing.
A MEMBER: Will birds or any kind of poultry eat them?
DR. ADAMS: Yes, poultry will eat them, as far as they can reach. Certain birds, of course, will feed on them to some extent, but birds, in summer, seem to have plenty of other things to eat, and they certainly leave plenty of beetles in plain sight uneaten. We can see that the birds are a fairly constant helpful factor, but are not to be relied upon to prevent injury occurring in a beetle outbreak.
Rotenone, which, I believe, is one of your main insecticides in nut culture, is fairly effective on Japanese beetles. It kills the beetles hit with the spray and gives protection for several days thereafter. If you apply it often enough, rotenone can take care of the plants so that they don't become disfigured by the beetles. Using cube powder, you may apply five ounces of 4% rotenone in 10 gallons of water. Of course, in many cases there is no objection to using DDT wetable powder or dusts, unless you are afraid of a mite problem arising after DDT is used. If DDT can be sprayed on the plants, it needs to be applied only about three times during a summer, or sometimes only twice. For plants that are growing very fast, the new growth, of course, has to be kept treated. You may prefer to spray once heavily over all the plants in July and then, after that, keep the beetles off by spraying or dusting the new growth, during August. For more directions see U.S.D.A. Farmers Bulletin No. 2004.
Now, there are new chemicals that will kill Japanese beetles very quickly. Parathion will kill them, but its toxicity necessitates great care in handling and, on peaches, we find it protects the plants for only a few days. Chlordane, which has a very important use in connection with these insects in the grub stage, is not recommended above ground; it is too brief in its action. Methoxychlor may be used instead of DDT. It is less effective, but much less poisonous, and should be applied more frequently.
Now, the other aspect of control is to try to reduce beetle production over the whole area so that you don't have so many beetles flying in to the plants during the summer and you don't have to spray so frequently, if at all. This is the phase to which I wish to give particular attention, after we consider the life history.
~Life history:~ The Japanese beetles in the adult stage are in evidence here from late June to late September, or, roughly, for the summer season. The adults lay their eggs in the soil, mostly in lawns, mowed grassy fields and pastures. The adults die but the eggs give rise to tiny, bluish-gray larvae which feed chiefly on grass roots. The larvae grow through the fall and spring, and, if more numerous than about 40 to the square foot in September, or about 25 in April and May, can cause severe lawn damage.
MR. CORSAN: That's the stage when the pheasants and starlings eat them.
DR. ADAMS: Yes, in the grub stage.
MR. CORSAN: I see thousands of starlings gorging themselves.
DR. ADAMS: Yes, scratching birds, crows and skunks can take them out; the starlings make a hole the size of a pencil point to do so. In our survey areas grub populations sometimes seem to drop rapidly in May, when the birds are feeding their nestlings. In June, the surviving larvae mostly change into pupae, and by July they are appearing as beetles. From the lawns and grassy fields they readily fly to weeds, shrubs, grapevines and trees. They fly at least a few hundred yards, if need be, to find their host plants. Well kept, sunny, lawns with good, moist soil, which carry 40 grubs to the square foot in the fall may still have plenty at transformation time in early summer. A lawn of 5,000 square feet could thus produce 100,000 beetles. Yards, roadways and pastures commonly produce as many as six beetles to the square foot, which means a quarter million to the acre.
~Chemical control in the grub stage:~ In New York we suggest that on a home property the more valuable sections of permanent lawn be grub-proofed with chemicals as soon as there are 5 to 10 grubs to the square foot. This grub-proofing has two effects: (a) it stops beetle production from that lawn, and (b) it prevents the lawn grass being damaged by the grubs of this and other annual grub species and by the birds and animals, including moles, which damage grubby turf. For grub-proofing I prefer to use chlordane. It may be applied in a spray, at 8 ounces of 50% wettable powder to 1,000 square feet, or it may be purchased in the more bulky 5% form and applied dry with a two-wheeled lawn fertilizer spreader. For each 1,000 square feet I take 5 pounds of 5% chlordane and, since it tends to clog the spreader, I mix it in a cardboard drum with 5 pounds of a dry, granular material such as the activated-sludge fertilizer known as "Milorganite." The ten pounds of mixture is then spread on the 1,000 square feet, half east and west, half north and south.
If applied in the fall or early spring there will be no beetles coming out in July and no grubs for several years. DDT at 6 pounds of 10% DDT to 1,000 square feet will give an even longer grub-proofing effect. Our plots so treated in 1944 are still grub-free. The possible trouble with DDT is that it is too nearly permanent, and if you should plow up a piece of lawn treated with it and try to raise tomatoes or strawberries, you might find the soil too toxic.
~Biological control in the grub stage:~ The chemical grub-proofing of the sunny parts of the front or main lawn on a property is desirable for the reasons stated, but it does not usually stop more than a fifth of the beetle production around the property, because there are usually plenty of neighbors' lawns, pastures, public grounds, and other beetle-producing turf areas nearby. How are you to reduce the beetle crop on these places, mostly on ground you don't control? Here is where biological control comes in, something which I feel will appeal to you in this group. The parasitic insects known as spring Tiphia, imported from the Orient and well established on hundreds of estates, golf courses, and cemeteries around Philadelphia and New York, may be introduced in your vicinity when grubs reach about 5 to the square foot. The parasites, which are like flying ants, appear above ground in spring and feed on honey-dew. The female burrows in the soil and attaches her eggs singly to Japanese beetle grubs. A maggot hatches and consumes the grub. I have charge of the distribution of these parasites in New York. I like to liberate at least one colony in each village or town division. Some of you may help me plan the liberation for your vicinity, possibly on a cemetery near your place. The colonies enlarge to about a square mile in 10 years, and may cut beetle production by 50%.
Another biological agent which can be added to grub-carrying turf is the bacterium causing Japanese beetle grubs to turn milky white and die. A powder is made from diseased grubs and talc and this milky disease spore inoculum is applied with a teaspoon in dots or spots over the turf. The important point is that the spore powder must be used on a plot where there are grubs to get the disease, and not on chemically grub-proofed soil. Milky disease spore powder is sold under three brand names, "Japidemic," "Japonex" and "Sawco-Japy." One-half pound, suitably applied, will cost you about $2.50 and be an act of good citizenship, for the disease slowly spreads to any grubby soil in surrounding properties. I can supply addresses of the producers and detailed reprints of my studies.
Discussion
MR. McDANIEL: Does this disease affect any other beetles we have inAmerica, besides the Japanese?
MR. ADAMS: Yes, one other species; it causes some sickness in the grubs of the turf pest known as the Oriental beetle.
MR. McDANIEL: How about the green June beetle?
DR. ADAMS: No, unfortunately, it doesn't work on that beetle, which is a pest on Long Island and in the South.
A MEMBER: How much area would a (1/2-pound) can like that treat?
DR. ADAMS: It depends. You can apply a half-pound to a quarter acre, or any smaller space you want to put it on. If you want to put spots down closer together, say every three feet, it will treat about 1,000 square feet. It suggests on the label that you do. But if you treat a plot on a large field, I'd recommend you put it out at about a teaspoonful every ten feet. In other words, I wouldn't put less than a half-pound on the plot set aside for it on my place. The application is just a starter to introduce the disease in the area, and it doesn't matter too much whether you spot it at 10-foot intervals on a pasture or put it at fairly close intervals on an area about the size of this room. The point is that it mustn't be broadcast, because that spreads the spores too thin. Grubs don't get the disease if they eat only a few spores. We assume that where you put the spots down on the ground the grubs under those spots will get the disease and wander off and die. When a grub dies, it multiplies the number of spores up to many millions. That portion of soil becomes infective, and more grubs going through the infective portions carry the disease to intervening areas until the whole piece of turf is unhealthful to these grubs. Droppings of birds feeding on sick grubs spread the disease.
MR. FRYE: One application is all that's needed?
DR. ADAMS: One application is all that's needed. Control is slight at first, but increases with the passage of the years.
MR. CORSAN: Quail feed on them. Why can't we have quail around the farms instead of shooting them?
DR. ADAMS: I would be for that, but we have to find other methods for a lot of people. Besides, we need something that will intercept some of the grubs in the fall, before they get big. After all, by the time the quail are interested in them, they have already done some damage in the ground. In the ground the grubs can do two kinds of damage. They can make turf loose so it can be rolled back like a rug. Second, if you should plow up a piece of sod that has many grubs in it and try to plant row crops or nursery stock, they may eat the roots off the planting in the spring.
DR. McKAY: I'd like to ask what effect low temperature has on them and how far north you think will be their limit?
DR. ADAMS: The soil temperature at which the grubs begin to die in hibernation is 15 degrees, and I have never seen the soil temperature that low here under turf. (I operate a soil thermograph on my lawn.)
A MEMBER: How far down do they go?
DR. ADAMS: They hibernate at 4 to 8 inches in the ground. It's rare to have it drop below 27 degrees at these depths.
MR. STERLING SMITH: What do you mean, Fahrenheit?
DR. ADAMS: That is Fahrenheit.
A MEMBER: That's frozen solid. That's at 32 degrees.
DR. ADAMS: The deeper soil will drop only a few degrees below freezing. The soil here usually remains no lower than 32 degrees, except within an inch or two of the top.
A MEMBER: Do you think soil temperature is going to be a limiting factor?
DR. ADAMS: I think the limiting factor northward is the coolness of the summers. In Northern Japan their life history gets altered because of the shortness of the summer, and I think in the Adirondack area they won't be serious for that reason.
MR. WEBER: Will this spore powder kill other kinds of grubs that are in the sod?
DR. ADAMS: Not to any practical extent. It does not control the grubs of the "June bugs," or brown June beetles, or what are called "white grubs."
MR. LOWERRE: Would the DDT kill the parasitic wasps?
DR. ADAMS: Turf treated with chlordane or DDT is grub-proofed and is not of any use to the flying parasites as a place to lay eggs, or for bacteria to multiply. So we don't want to put chemicals on top of biological control plots. For instance, on an average home property I would treat the front lawn, the more valuable piece, with chemicals so that it would be 100% grub-proofed to protect the turf and to take that much turf out of beetle production. Then on the back lawns or grassy fields adjoining, I would apply at least a half-pound of this milky disease material, and in that way provide a complete treatment; the parasites can be added on some large public turf area nearby. And don't think you are going to stamp the Japanese beetle out just by spraying all the adult beetles you see each summer on the cultivated plants, because there are lots more on the shade trees, weeds and vines.
A new book, "The Insect Enemies of Eastern Forests," contains a great deal of information on the insects feeding on nut trees. Unfortunately, it isn't indexed to crops, so you can't look up "walnut" and find what insects bother you. You have to know what the insect is, and you will find it with its insect family. That is U. S. Department of Agriculture Miscellaneous Publication 657, by George E. Craighead. Price $2.50, from the Superintendent of Documents, Washington, D. C.
MR. CORSAN: What in the world has become of the black walnut caterpillar, that big, black fellow with the grey hairs?
DR. ADAMS: Maybe they are at a low point in a cycle. Mr. Bernath will show you a few of them.
MR. CORSAN: He might show me a few of them, but I have been pestered with them for years, and this year I haven't got any.
DR. ADAMS: I suppose natural conditions have taken care of them for a while, but they will come back again.
(Applause.)
DR. MacDANIELS: Thank you, very much, sir. We will take a few minutes recess now.
(Whereupon, a short recess was taken.)
Editor's Note: The following paper which was delayed, was originally scheduled for our 1949 Report.
Insecticides for Nut Insects
E. H. SIEGLER United States Department of Agriculture AgriculturalResearch Administration Bureau of Entomology and Plant Quarantine
Fortunately, the growers of nuts do not have to combat a large number of injurious insect species. However, some species do at times cause a heavy loss of nuts and may also damage the vegetation growth of the trees. Injury by insects will vary from year to year, due to various causes, and insects frequently show varietal host preferences. Timely use of insecticides is the most effective means of combating many harmful species.
Until the beginning of World War II a rather limited number of insecticides was available, such as lead arsenate, cryolite, nicotine, mineral oil emulsions, and rotenone. Some injurious insects were satisfactorily controlled through the timely application of one or the other of these materials, or combinations of them; others survived in damaging numbers in spite of all attempts to suppress them.
During and since World War II, both in the United States and abroad, work on insecticides has been stepped up markedly. As a result, many new insecticides have been developed and are available for general use.
The first of the new insecticides about which we heard was DDT. Actually, the compound itself was not a new one, since it was prepared by a German student chemist in 1874. However, no use was found for it until 1939, when a Swiss chemist found it promising as an insecticide against the Colorado potato beetle. It was first tested in the United States a few years later.
Since the successful introduction of DDT, promising new insecticides have become available more frequently and in greater numbers than ever before. Among these materials are certain chlorinated hydrocarbons related to DDT. These include methoxychlor and TDE, neither of which is, on the whole, as useful as DDT but both of which are of value and have an important advantage over DDT in that they are reported to be less toxic to warm-blooded animals. Other new chlorinated hydrocarbons include benzene hexachloride, synthesized in 1828 and first tested against insects in France in 1941 and discovered about the same time in England; chlordane, developed in the United States a few years ago; and toxaphene. Several organic phosphorus compounds, including hexaethyl tetraphosphate, tetraethyl pyrophosphate, and parathion, have also been developed.
Technical benzene hexachloride is a mixture of several isomers, the gamma isomer being the most toxic to insects. The practically pure isomer is known as lindane. A handicap to the general use of benzene hexachloride on fruit is its tendency to cause off-flavor condition when applied too close to harvest. Lindane is less likely to cause off-flavor in fruit than technical benzene hexachloride but may not overcome this fault altogether.
The organic phosphate insecticides, like DDT, were first found of value in Europe and were introduced into the United States after the close of World War II. Parathion in particular shows great promise for the control of many insect pests. Although these compounds are very poisonous and must be handled strictly in accordance with the manufacturers' recommendations, a recent announcement by Arnold J. Lehman, of the Food and Drug Administration, indicates that their residues are not likely to be harmful. He has stated that "parathion is not stored in the tissues to an appreciable extent—it is rapidly destroyed by the tissues of the body which in turn is an added mechanism for the prevention of tissue accumulation." Residues of hexaethyl tetraphosphate and tetraethyl pyrophosphate persist for only a short time and residues of parathion drop to a low level within 10 to 14 days after application. This information, however, does not make it unnecessary for the user to observe strictly all warnings and precautions issued by the manufacturers of parathion and of other organic phosphates. Serious effects and deaths have occurred though excessive exposures to parathion.
General Information Regarding the Use of the New Organic Insecticides
~Handling the insecticides.~ All the new organic insecticides, the organic phosphates in particular, are to some degree toxic not only to many insects but to man and animals as well. Even the most toxic ones can be used, however, without harmful effects on the operator, provided all the cautions issued by the manufacturer are properly followed. Special care must be taken in handling concentrated insecticides preparatory to making diluted spray or dust applications.
~Spray concentrations.~ DDT has been used more extensively than any of the other newer insecticides and for this reason there is considerable information relative to the spray concentrations known to be effective against insects susceptible to it. For spray purposes DDT is generally employed at the rate of 1-1/2 to 4 pounds of 50 percent wettable powder per 100 gallons of water.
Parathion is being used at 1/2 to 1-1/2 pounds of 15 percent wettable powder per 100 gallons of water for mites and up to 2 pounds to 100 gallons of water for insects more resistant to it. The occurrence of injury to the foliage and fruit of some varieties of apples when this insecticide is used is under investigation.
Benzene hexachloride (10 percent gamma isomer, wettable) is being used at 2 to 4 pounds, and sometimes less depending upon the insect, per 100 gallons of water. Wettable mixtures containing 25 percent of lindane (approximately pure gamma isomer) are used at dosages which would give an equivalent quantity of the gamma isomer in the diluted spray.
Chlordane is usually employed at the rate of 2 to 3 pounds of 50 percent wettable powder and toxaphene at 2 to 4 pounds of 40 percent wettable powder per 100 gallons.
These insecticides are also being sold for use as dusts, either ready to use or in a more concentrated form which can be reduced to dusting strength through the addition of inert material.
~Spray Residues.~ Spray residues are not important on nut crops, but on fruits it is important to time the insecticide applications so that harmful residues are avoided. Animals should not be allowed to graze vegetation beneath trees recently treated. Instructions on the packaged insecticide should be followed.
~Effect on beneficial insects.~ Since the more potent of the newer organic insecticides are toxic to many parasitic and predatory insects, all of which help to reduce the populations of injurious species, these insecticides, if used, must be largely relied upon to effect control by themselves. Often no immediate assistance is forthcoming from beneficial insects after these materials have been used.
Nut Insect Investigations
Except for studies on the chestnut weevils, nut insect investigations by the Bureau of Entomology and Plant Quarantine are being conducted primarily on the pecan at southern laboratories. Many of the remarks in this paper are therefore based on information obtained from these laboratories. In view of the short time the new organic insecticides have been available, work to determine their place in nut insect control programs is largely in the experimental stage. Much further work will be necessary before detailed instructions can be given for their general use.
Insects Attacking the Nuts
~The Pecan weevil.~ The adult of the pecan weevil[8] is a snout beetle that attacks not only pecan throughout the South but also hickory in the eastern half of the United States. During mid-season, previous to the formation of the kernel, nuts are frequently punctured for feeding purposes. This results in failure of the nuts to complete their development. The principal injury, however, is caused by grubs that develop from eggs laid in the nuts after the kernels have formed. This is usually during September on pecans in the South. The grubs feed on the kernels and may consume them completely (Fig. 1).
[8] ~Curculio caryae~ (Horn).
Applications of sprays containing 6 pounds of 50 percent DDT wettable powder per 100 gallons of water just previous to and during the oviposition period have proved effective against this pest.
[Illustration: Fig 1.—Nut infested with larvae of the pecan weevil.]
[Illustration: Fig. 2.—Larva of the butternut curculio in Japanese walnut shoot.]
[Illustration: Fig. 3—Adults of the walnut husk maggot on black walnut.Enlarged.]
[Illustration: Fig. 4.—Adult of a leaf-footed bug. Enlarged.]
[Illustration: Fig. 5.—Defoliation caused by the black pecan aphid.]
Nut curculios. Several species of curculios, such as the butternut curculio[9] (Fig. 2) and the hickorynut curculio,[10] infest the fruit of these and other nut trees. Their life histories and methods of attack are somewhat alike and for the purpose of this report the butternut curiculio is given as an example. This insect lays its eggs in both the young shoots and nuts, which usually drop as a result of the injury. The larvae then develop to maturity within the dying tissues after which they enter the soil and transform to adults. Subsequently they leave the soil to pass the winter above ground protected from low temperatures by weeds or other vegetation.
[9] ~Conotrachelus juglandis~ Lee.
[10] ~Conotrachelus affinis~ Boh.
Lead arsenate, 4 pounds per 100 gallons of water, has been relied upon in the past for control of various nut curculios. Among the newer insecticides, benzene hexachloride (6 percent gamma), 4 to 6 pounds per 100 gallons, has shown promise against a shoot curculio on pecans when applied soon after the trees start growth in the spring.
~Hickory shuckworm.~ The hickory shuckworm[11] is another serious pest of pecan and hickory nuts. Early in the year, previous to the hardening of the shells, the kernels are eaten. This injury causes many of the nuts to drop. In the fall, the later generations tunnel within and feed upon the shucks only. The affected nuts are usually smaller than normal; in addition the shells are often stained and are more difficult to separate from the husks.
[11] ~Laspeyresia caryana~ (Fitch).
Extensive experimentation in the control of this insect has been carried out without much success. No effective insecticide treatment can be recommended for its control.
~Walnut husk maggot.~ The adult of the walnut husk maggot[12] is a fly (Fig. 3); it is related to other injurious fruit flies such as the apple maggot, Mediterranean fruit fly, and the oriental fruit fly, which has recently been found in Hawaii. Adults emerge from the soil and fly to the trees in midsummer. Egg laying follows in 1 to 3 weeks, the eggs being deposited on the husks of several kinds of nuts. The maggots feed within the husks. Not only is the quality of infested nuts lowered, but, in addition, the husks are more difficult to remove. A closely related species is particularly damaging to the Persian or English walnut in California.
[12] ~Rhagoletis suavis~ Loew.
Lead arsenate, 2 to 4 pounds per 100 gallons of water, in combination with an equal quantity of hydrated lime is quite effective in destroying the adults of the walnut husk maggot when applied at the time they are present.
~Stinkbugs and leaf-footed bugs.~ There are a number of stinkbugs and leaf-footed bugs (Fig. 4), in addition to the species mentioned,[13][14] which are responsible for important injuries to pecans, filberts, and other nuts. These insects puncture the immature nuts with their beaks. The punctured areas become spongy, somewhat dark in color, and are bitter to the taste; on pecan the typical injury is referred to as black pit and kernel spot.
[13] ~Nezara vizidula~ (L.).
[14] ~Leptoglossus phyllopus~ (L.).
Crops of favorable host plants such as cowpeas and soybeans should not be planted in or adjacent to nut orchards subject to attack by these sucking bugs. In general, orchard sanitation should be practiced.
[Illustration: Fig. 6.—Galls produced by the pecan phylloxera.]
[Illustration: Fig. 7.—Injury to young pecan tree by the fall webworm.]
[Illustration: Fig. 8.—Larvae of the walnut caterpillar.]
[Illustration: Fig. 9.—Caterpillar of the hickory tussock moth.]
[Illustration: Fig. 10.—Rose chafer beetles on chestnut blossoms.]
Insects Attacking the Foliage
~Black pecan aphid.~ Pecan trees at times suffer sufficient damage from the black pecan aphid[15] to cause considerable defoliation (Fig. 5) during the latter part of the season. The injury to foliage in its earlier stages consists of irregularly shaped yellowish areas which turn brown when the tissues die.
[15] ~Melanocallis caryaefoliae~ (Davis).
This aphid is usually controlled with nicotine sulfate (40 percent nicotine), 3/8 pint plus summer oil emulsion, 2 quarts per 100 gallons of spray. Parathion and benzene hexachloride have given good results in experimental work but are not yet generally recommended.
~Pecan phylloxera.~ The pecan phylloxera[16] is related to aphids. It attacks principally the vegetative parts of the tree such as the leaves, petioles, and shoots on which galls (Fig. 6) are produced. Pecans, hickories, and other species of nuts are subject to infestation.
[16] ~Phylloxera devastatrix~ Perg.
In the past a spray of nicotine sulfate (40 percent nicotine) 13 ounces combined with either lime-sulfur solution, 2-1/2 gallons per 100 gallons of water, or lubricating-oil emulsion, 2 quarts per 100 gallons, applied in the late dormant period has been the standard recommendation. In recent experiments in the South with some of the new organic sprays, benzene hexachloride and some of the dinitro compounds have indicated good promise.
~Fall webworm,~[17] ~walnut caterpillar,~[18] ~and hickory tussock moth.~[19] The caterpillars of these species (Figs. 7, 8, 9) are frequent pests on the foliage of nut trees. They often defoliate entire branches.
[17] ~Hyphantria cunea~ (Drury).
[18] ~Datana integerrima~ (G. and R.)
[19] ~Halisidota caryae~ (Harr.)
The best time to apply control measures is as soon as possible after the caterpillars hatch. The insects can be readily destroyed with lead arsenate, 3 pounds, or DDT (2 pounds) of 50 percent wettable powder, per 100 gallons, applied when they appear. Other new organic insecticides may also be effective but have not been widely tested.
~The rose chafer and Japanese beetle.~ Adults of the rose chafer[20] (Fig. 10) and the Japanese beetle[21] are voracious feeders on the foliage of nut trees and must be destroyed if severe injury is to be avoided.
[20] ~Marcordactylus subspinosus~ (F.).
[21] ~Popillia japonica~ Newm.
Fortunately these insects may now be controlled by spraying with DDT, 2 pounds of 50-percent wettable powder per 100 gallons of water, when the beetles appear. In the case of the Japanese beetle a second application may be necessary if the infestation is heavy.
~Spider mites.~ Nut trees, especially those which have been sprayed with DDT, may become seriously injured by various species of mites.[22] DDT is very toxic to the natural insect enemies of plant-feeding mites and therefore the mites build up to injurious numbers.
[22] ~Tetranychus~ sp. and others.
Of the various miticides recently tested on pecan, a spray of parathion was the most promising. In some recent tests for the control of spider mites on chestnut trees, 1-1/2 pounds of 15 percent parathion wettable powder per 100 gallons of water was effective. Do not use parathion unless you observe all the precautions contained on the package label of the material.
[Illustration: Fig. 11.—Larva of the twig girdler. Enlarged.]
[Illustration: Fig. 12.—Adult of the flatheaded apple tree borer.Enlarged.]
[Illustration: Fig. 13.—Larvae of the flatheaded apple tree borer.]
[Illustration: Fig. 14.—Scars on trunk of pecan tree caused by cutting out flatheaded apple tree borers from their tunnels.]
[Illustration: Fig. 15.—Adult of the buffalo treehopper. Enlarged.]
[Illustration: Fig. 16.—Twig scarred as a result of egg laying by the buffalo treehopper.]
Insects Attacking the Trunk and Branches
A number of insects cause important damage to the trunk and branches of nut trees.
~Obscure scale and others.~ The obscure scale[23] infests a variety of nut trees. On pecan the chief injury results from attacks on branches under three inches in diameter.
[23] ~Chrysomphalus obscurus~ (Comst.).
The obscure scale and other scale insects can be controlled with lubricating-oil emulsion during the dormant period. However, nut trees are often susceptible to oil damage, especially at 3 percent concentration. Since healthy trees are more resistant to oil injury, it is therefore advisable to watch for scale infestations so as to spray them before the trees are weakened.
~Twig girdler.~ Nut trees are sometimes attacked by the twig girdler[24] (Fig. 11). This beetle lays eggs in the twigs, which are girdled so as to stop the flow of sap that would normally prevent hatching. The girdled twigs usually become detached from the trees and as a result the nut-bearing wood is reduced.
[24] ~Oncideres cingulata~ (Say).
The standard recommendation for control of this insect has been to gather and destroy the infested twigs in the orchard and from any infested trees nearby. Recent tests on pecan in northern Florida indicate that DDT and parathion may be effective against this insect. Three applications (the first on August 26 when the first girdled twigs were observed and the others on September 9 and 23) of DDT, 4 pounds of 50 percent wettable powder per 100 gallons of water, or parathion, 3 pounds of 15 percent wettable powder per 100 gallons, gave complete control. Further experiments will be required to determine the minimum effective concentration of spray and the number of applications needed for control. It is suggested that DDT be used for the control of this insect until more information is available on how to handle and to use parathion.
~Flatheaded apple tree borer.~ The adult beetle of the flathead apple tree borer[25] (Fig. 12) deposits its eggs throughout the summer season, preferably in the small grooves of bark on the unshaded portions of the trunk of pecan and other trees. The borers (Fig. 13) hatch and tunnel through the bark to the cambium layer. Young trees may readily be girdled (Fig. 14).
[25] ~Chrysobothris femorata~ (Oliv.).
To avoid this insect as far as possible, orchard sanitation should be practiced and the trees should be kept in a healthy condition. In some plantings wrapping the trunks with paper or burlap to protect against egg laying and maintaining low branches to shade the trunk have been helpful. Cutting out the borers with a knife has also been resorted to; trunk washes have likewise been used but have not been very effective.
~Buffalo treehopper and periodical cicada.~ Buffalo treehoppers[26] (Fig. 15) and the periodical cicada[27] weaken twigs by inserting their eggs in them. The injured bark becomes roughened as it heals (Fig. 16), and the growth of the limb is retarded.
[26] ~Ceresa bubalus~ (L.).
[27] ~Magicicada septendecim~ (L.).
Pruning of weakened twigs is recommended for wood injured by the cicada. If treehoppers are a pest, clean cultivation will help. Cover crops of cowpeas or clovers should not be planted. In preliminary tests two or three applications of tetraethyl pyrophosphate (20 percent), 3/4 pint per 100 gallons of water, have given promising results in controlling the periodical cicada. The first application should be made after the cicadas appear and the others as needed to prevent damage.
Observations on Effects of Low Temperatures in Winter 1949-1950 onWalnuts and Filberts in Oregon and Washington
Horticulturist, United States Department of Agriculture, AgriculturalResearch Administration, Bureau of Plant Industry, Soils, andAgricultural Engineering, Oregon State College, Corvallis, Oregon
In western Oregon and Washington, where the Japan Current is supposed to keep the winter temperatures moderate, something happens every now and then and we get really severe winters. We can't blame it on the "A" bomb because we had severe winter injury in 1919 and 1935 long before the "A" bomb.
The last two winters have been exceptionally cold, but this past winter of 1949-1950 was much more severe than the previous one.
In 1948-1949, the cold came rather suddenly in the latter part of December. In the past winter, 1949-1950, the real cold came on January 30, with temperatures ranging from 10 to 30 degrees below zero F. Most official temperatures were higher; but at Corvallis the official temperatures were taken at least 60 feet above the ground level, on the roof of the Agricultural Building, which is over a steam-heated building and is old enough to be not very well insulated. This cold continued in somewhat modified form for a week.
During the previous winter the lowest temperature recorded in the nut growing areas was about 10 to 11 degrees above zero F., and the severe cold lasted for only a couple of days.
In both winters the ground was fairly well covered with snow, but with considerably more snow this past winter than the previous winter.
No apparent damage to Persian walnuts was observed as a result of the cold in the 1948-1949 winter, but in certain low-lying areas catkins of Barcelona and Daviana filberts were killed, especially those of the latter. Considerable dieback of filberts occurred; but during the following growing season recovery was effected and at the end of the summer very little evidence of winter injury was visible.
The injury resulting from the cold weather of the past winter was much more severe than that of the previous winter. Whereas filberts were the only nut trees injured in 1948-1949, they escaped with relatively little damage in 1949-1950 in comparison with Persian walnuts.
On February 11, 1950, ten days after the really severe week, several walnut growers of long experience held grave fears for the entire industry. Peach and apple trees, which seem to exhibit winter injury more quickly than walnuts, showed so much damage then that walnut growers thought the injury to the Persian walnut would be even worse.
From February 11, 1950, to the present date (July 30) I have been making observations from time to time in different locations with special attention to walnuts and with some to filberts. It is thought that certain of these observations might be of interest to nut growers in other areas, even though there is nothing particularly new or startling about them. They do, however, tend to show how surprisingly well the Persian walnut trees can withstand severe cold if it occurs after they have once gone into dormancy.
Generally speaking, the winter injury to walnuts has been spotty. No areas of great size have been either free of injury or severely injured. Usually, where a difference in severity of damage is found between areas close together, some reason for the difference can be found, but it is not always evident on the surface.
Injury to Walnuts
With the possible exception of southern Oregon, it is safe to say that 100 percent of the walnut trees in Oregon and Washington suffered some twig injury as a result of last winter's cold. In many cases the subsequent dieback of the twigs may extend only a few inches, but sometimes the injury involves not only the past season's growth but that of three or even four years back.
As might well be expected, this twig injury of necessity has meant the loss of many terminal and lateral buds which bear the female flowers; so for that reason, if for no other, this twig injury has assumed serious aspects.
In many cases the catkins were severely injured even where there was little or no twig injury. The catkins of the Persian walnut seem to be extremely sensitive to cold. Many Persian walnut trees in Oregon this year failed to produce any catkins at all. Some produced very few normal catkins, but some half-developed and deformed catkins. An examination of these partially injured catkins, however, revealed the fact that they did produce some pollen. It will always remain a mystery to me how as many walnuts were pollinated and set as there were, with the scant crop of catkins.
In practically every orchard examined, where the temperature got as low as minus 10 degrees F., the pith cells were blackened. This is not uncommon in other tree crops following severe winter injury. Fairly good peach crops have been borne in Georgia on trees that had the pith cells completely blackened.
In the case of walnuts this year, many growers were considerably worried by the fact that even the wood tissue outside the pith region was black and watersoaked. However, to date (July 30, 1950) this condition has not proven serious; as long as the cambium cells were not injured no real trouble has developed. In some cases under observation, even where some injury to the cambium cells was known to have existed, enough live ones have been left to effect recovery. Compared to peach, holly, and even apple trees the Persian walnut has put up a marvelous fight to recover from the injury sustained.
Factors Accentuating Winter Injury in Walnuts
After the several months of observation, certain factors appear invariably to account for excessive damage to walnut orchards. Elevation seems to be a principal factor. The hillside orchards or those on upland sites (soils) were far less injured than the river-bottom or valley-floor orchards, even though the latter may be on a better soil as far as fertility is concerned. My early prediction of 50 percent of a crop in the hillside orchards seems now to have been about 10 percent short, unless other factors become involved. On the other hand, my early prediction of 25 percent of a crop in the valley-floor orchards has been close to correct. Of course, certain valley-floor orchards with a combination of adverse factors won't have even a 5 percent crop.
Older orchards were more severely hurt than younger orchards with otherwise similar conditions. This is possibly due to the lack of vigor and of reserve material, resulting from crowding and competition for elements of nutrition.
The size of the crop the preceeding year seems invariably to have had an effect upon amount of damage done. The matter of reserves is again involved. Two orchards that bore a reduced crop last year because of spring frost injury have come through much better than some other similar orchards, at practically the same elevation and age, that bore a crop last year.
Two adjacent hillside orchards show considerable difference in degree of winter injury and crop prospects for this year. It is believed that this difference was due to the fact that in one orchard 35 percent of the crop was destroyed by blight last year, in comparison with a 1 percent loss in the other. The owners and I estimate that there is at least 20 percent larger crop this year in the orchard which had the heavy loss from blight last year.
In several orchards where different levels of fertilization have been used by the grower, it appears that the more liberal the application of fertilizer, particularly nitrogen, the less severe was the winter damage sustained.
At the college orchard in Corvallis, the one tree that got no additional nitrogen last year and that bore the heaviest crop of nuts is outstandingly the most severely winter injured of the 17 trees involved.
Only two varieties of walnuts have been studied, Franquette and Mayette, and some Carpathian seedlings in one orchard. Here in Oregon the Mayette seems to have generally withstood the winter injury better than the Franquette. It is my belief that they are just naturally a little more vigorous than the Franquette. Yet they never seem to overproduce as the Franquette sometime does. Last year was the "on" year for Franquettes and that might easily account for the generally apparent better condition of the Mayettes this year.
Carpathians Resist Winter Best
Near Ontario, Oregon, I saw 7 seedling Carpathian walnut trees early this spring. They were leafed out and the catkins were elongated before any Franquettes, even in the Willamette Valley, had started breaking buds. No sign of winter injury was apparent on the Carpathian trees at that time, yet Franquettes at the Malheur Experiment Station, a mile away, were obviously killed to the groundline. The owner, Mr. Peter Countryman, says these trees are often damaged by spring frosts but they always produce some nuts.
A letter dated August 4, from Mr. Countryman, indicates that a hard frost on the morning of April 24 when the temperature dropped to 22 degrees, did considerable damage to the new growth and catkins on the lower half of the Carpathian walnut trees. He estimates not to exceed one-third of a crop on these Carpathian trees this year; but he says that since the freeze the trees have made good growth, the new terminals being about 18 inches in length and the nuts on them are very large.
To sum up the walnut situation, then, the encouraging thing is that no walnut orchards have been called to my attention that were completely killed. Several badly neglected orchards and two orchards where it is said that the temperature dropped lower than minus 25 degrees F. are so severely damaged that it is impractical to try to save them, but even these are not completely killed.
Injury to Filberts
From the less comprehensive observations made on filberts following the severe winter just past, it appears in general that when the filbert tree has gone into dormancy it is more tolerant of cold than the walnut. The difference of one month in time of occurrence of the cold in the two winters seems to have had more bearing on the damage to filberts than the difference in temperature. In the Forest Grove, Oregon, area, and in Clark County, Washington, filbert trees, however did suffer severely from the cold last winter, but these two areas were the "cold spots" of the Northwest.
It seems as if the same factors that accentuate winter damage in walnuts work in a similar way on filberts, except that the elevation factor does not seem to be of so great importance. Age of tree, level of nutrition, and size of preceeding year's crop seem to be more important than elevation. Young filbert orchards, on either hillside or valley-floor sites, seem to be much less severely hurt than older orchards on the same sites. It is the acreage ofyoungfilbert trees that will make good the agricultural statistician's estimate of 40 to 50 percent of a filbert crop this year.
I have seen one 32-acre orchard of 24-year-old filbert trees that was injured beyond repair, but they were crowded and unfertilized. At the very same location a 14-acre orchard of 15-year-old filberts with adequate spacing was not seriously injured, even though the trees were not fertilized.
One other orchard in a poor location and on waterlogged soil, which has had little or no care, has likewise been lost. Filberts definitely were hurt in the two "cold spots" previously mentioned, but official reports of minus 18 degrees F. were common in that area.
There was a noticeable difference in damage to catkins between Daviana and DuChilly. Very few Daviana catkins produced pollen; but DuChilly seemed to be fairly normal.
Injury in filberts was confined mostly to the catkins and twigs. Excessive sucker growth up and down the main trunk and branches has taken place in the filberts, as is the case in walnuts.
In neither walnuts nor filberts was there much splitting of the bark on the trunk. This was probably because there was no sudden fluctuation in temperatures and sunshine was not excessive during the critically cold days.
It has been previously stated that the filbert is possibly more tolerant of cold than the walnut. In spite of this there probably has been more extensive damage to filberts than to walnuts; but it must be remembered that filberts are the principal nut crop in those two "cold spots." Not many walnuts are grown there, but the ones that are were likewise injured.
Editor's Note: Mr. Gellatly's following papers were read by title.
Effects of the Winter of 1949-50 on Nut Trees in British Columbia
Box 19, Westbank, B. C.
(Orchard at Gellatly, B. C.)
Our district is just recovering (in August) from the effects of the toughest winter we have experienced here in the past 50 years. This gave the weather test to the tune of -22° F., official. The unofficials were of 30 to 40 below—depending on distances and location from Okanagan Lake, a deep body of water three to four miles wide and eighty miles long. This lake rarely freezes over completely, especially near our section; so the open water acts as a thermostat during most winters. But the past one pulled a new stunt and it froze over completely giving zero winds a vast open sweep, so that to be near the lake was a disadvantage, for it was colder there than it was farther back, in more sheltered locations.
Heartnuts and Hybrids
The bright spot in the nut tree picture is our heartnut trees. They all came through in good shape, making rampant growths and carrying a heavy crop. These include: 2 Walters, 4 O.K. Heart, 1 Canoka, 1 Slioka, 1 Rover, 2 Calendar, 1 Westoka, 1 Nursoka, 1 Aloka, 1 Symoka, 15 select unnamed bearing seedlings, yet on trial. All are promising. Also we have three of the Elfin paper shell heartnut hybrids. I have failed to find a good pollinator for these Elfins, so they are shy croppers, although producing plenty of the female blooms. All of the above trees are 6 inches in diameter and up to 20 inches.
Then come the Buart nuts. I coined this name to designate the hybrids I had made having the butternut (~J. cineria~) as the pollen parent and Calendar heartnut (~J. sieboldiana cordiformis~) as the mother tree. Possibly the seven best of these are: Leslie, Dunoka, Fioka, Okanda, Kingsbury, Penoka, Flavo. These trees are all carrying crops and most of them are making good growth.
Filberts
Ackerman, Brag, Comet, Craig, Holder, Petoka, Carey, Baroka, Barcelona, Bawdin, Firstoka (Gellatly No. 1). These have made a good showing, as the majority of the trees or bushes under 4 to 6 inch crown diameter of these varieties, are doing well and carrying good crops, while many above these diameters suffered in varying degrees from slightly to severely, apparently regardless of variety, location, or soil on which they grew. It may be noted that all these varieties have been hardy in the past, but age was adding up and age evidently had somewhat to do with their inability to take the punishment they got this past winter. For all my large Bing and Lambert cherry trees were severely injured or entirely winter killed, as were nearby peaches, apricots, pear, and some apple trees, particularly in the larger sizes, while many of these younger trees were uninjured, except that they are fruitless this season.
Soft Shell Walnuts
(Juglans regia)
Broadview variety on Gellatly Farm, of 20 bearing trees, all suffered winter injury for first time in 20 years. This injury varied all the way from freezing back two to three feet of all higher branches and twigs, to an actual loss of one-third to two-thirds of entire tree and trunk. At date of writing all are staging a good comeback with no care but a "wait-and-see" policy as to final treatment. There was so much loss as to involve too much work if pruning and after care of sprouts were undertaken. It was decided to leave the dead limbs and branches as a protection to the fast growing new sprouts, which, without this protection, would probably have been badly damaged by wind and rain storms. Even large birds lighting on these new sprouts might break them down.
The dead limbs will be gradually removed later, as the new limbs harden up and take over. Many of these will be left as supports for at least two years, when I expect most of these trees will be back in production, if we get a return to normal (minus 10° F.) winters, many will produce in 1951, as the new wood is showing a good growth of catkins. Although all bearing trees on my place were injured, the younger trees in my nursery were not hurt to any noticeable extent. At Summerland Experimental Station, 25 miles south of Gellatly, grow two large Broadview walnut trees supplied by myself. I had grafted on these black walnut roots (~J. nigra~) at the ground line, in every respect like my own. These trees are carrying a good crop. One shows slight winter injury, the other none at all. The official low for their location was 22° below F. with nearby unofficials to 30° below.
Their present location is at least 200 feet above lake level, and on very well drained sandy loam. Mine are about 30 feet above the lake and on somewhat heavier loam. I note that trees on my more gravelly soil came through in the best shape at official-22° F., unofficial 24 to 28 below. My Broadview that made best survival had grown the previous year in a chicken yard. Ground was well scratched over and droppings incorporated in top 4 inches of soil. Tree was flood irrigated three or four times in dry season. On this tree only outer new branches were killed and tree gives every indication of being back in crop in 1951 season.
The crop record on this tree is from 1945 and reads '45—35 pounds; '46—75 pounds; '47—91 pounds; '48—36 pounds; '49—100 pounds. Weight is for clean, undried, and partly dried nuts at time of picking up. Some of the other Broadview trees have higher crop records, although of same age and size, with possibly a bit better soil, in same grove. One tree in six years, '44 to '49 inclusive, had an average of 74 pounds per year; another had an average for the same years of 104 pounds per year. Just recently I made a special trip to see how the parent Broadview tree had wintered. I found it had sustained severe damage to two-thirds of the upper part of the trunk and main branches. The lower third was staging a good comeback, despite unofficials of 35 to 40 below zero F. as reported by neighboring farmers.
The following varieties of soft shell bearing walnut trees were also winter injured: Munsoka, badly, top two-thirds of trunk; Linoka, badly, top two-thirds of trunk; Myoka (Jumbo type) one-third of top branches; Geloka (Jumbo type) frozen to ground line but sprouts two feet high now growing. On Sirdar (a Jumbo type long nut), only outer tips of branches were killed. This was a surprise to me, as it is a second generation seedling of Italian source. The parent tree grew and cropped well for many years on bench land at Sirdar, in southern interior of B. C. until the winter of 1935-36, when it was so badly damaged that the owner had it removed. I rather looked for a similar fate in this one. There is this difference: mine was not as old nor had it been cropping heavily as yet. The season here is barely long enough to develop fully the kernels of Sirdar.
Crath Carpathian Walnut No. 46
This walnut was grafted on black walnut (~J. nigra~) root in 1944 and planted here on low loam soil in 1945. It never has been hardy under our conditions, winter killing some every winter since it was planted. This past winter it was killed to below snow line 18 inches above union, whereas Broadview trees alongside, which are the same in every respect, never were injured until this past winter. Then only minor damage to soft new growth was done. So it looks as though Broadview is still the best bet for our conditions.
I am of the opinion that extreme temperature is not the sole determining factor in causing winter injury to nut or other trees. This opinion is based on the behavior of trees that have winter killed continuously while in certain soil, but on being moved to another spot having enriched soil of similar make-up and drainage located only 200 yards away, have never winter killed since removal, and have taken much worse winters, including the one just past.
The fact that many of our introductions grow and thrive 150 to 200 miles north of here, where temperatures drop to minus 35° to 40°, with occasional drops to 54° below zero. Check this on your map of Interior of B. C. on 53° latitude at Quesnel, B. C. I see a geology map lists that district as sedimentary and volcanic rocks. My informant grows butternuts, chestnuts, and filberts. Another grower at Clinton, located on 50° latitude, central B. C. with temperatures to minus 40° F., grows Japanese and black walnuts, also Pioneer almond. We are sure that the same temperatures with our conditions would kill most of our trees.
Recipes
Walnut Honey Sandwich
1 Teaspoon crystallized Honey (the coarser the crystal the better) 3 Broadview walnut half kernels or quarters.
Place honey on one-half kernel, then stick the other half on the honey, making a small sandwich, or kernel covered ball of honey. This is a delightful confection.
Potato Nut Soup
1. Grate 1 tablespoon onion. 2. Grate 1 good-sized potato.
Place in double boiler, stir while adding boiling water, to a thin paste. Stir until cooked clear like corn starch pudding. Add hot whole milk to bring to creamy soup. At this stage add one-fourth cup filbert kernels. First put nuts through one of the new nut planing gadgets. These are better than the old grinder shredders or choppers, as shavings are so thin and soft they just melt in hot liquid. (Also delightful on ice cream or fresh fruit.) Have potatoes well cooked before adding milk or nut flakes. Cooking nuts too long sets up some chemical change that thins the creamy texture of the soup.
Description of Filazel Varieties[28]
[28] Since the Peace River hazel is apparently ~Corylus rostrata~ these filbert hybrids of Mr. Gellatly belong to a different category from the "hazilberts" of Mr. Weschcke and the "Mildred filberts" which had ~C. americana~ parentage.—J. C. McD.
The name (Filazel) I coined to designate those crosses I had made, having the Peace River hazel as the mother tree and Craig and others of our large filberts as the pollen parent.
Peoka
Has thin shell. Clean, well-filled kernel. Is heavy cropper and free husker. Nuts mature early. Are well filled by August fifth with shells starting to brown. Fully ripe by August tenth to fifteenth.
Manoka
One of the best of my first selections. Very attractive, heavy cropper, well-filled kernels by August first, shells coloring by August fifth. Ripe and falling August fifteenth.
Fernoka
Good cropper of roundish nuts, having short open husks and good clean kernels.
Myoka In clusters 1 to 6. Has short open husks. Leaves color well in the fall. Has ornamental value.
Fairoka
One to 7 nuts in cluster in fancy frilled and rolled back husk. Nuts roundish, of fair size and color. Flavor, good. Leaves color well in fall. Has ornamental value.
Maroka
Medium-sized nut exposed in clusters 4 to 6. Open husk, folded back.
Ureoka
Medium size for Filazel. Thin-shelled roundish nut, 4 to 6 in clusters.Very short, partially closed husk.
Orvoka
Two to 5 nuts in cluster. Clean kernels. Husk half-inch longer than nut.Has open side. Good cropper.
Brenoka
Long husk like parent hazel, but lacking prickles of the wild. Medium sized nut in clusters, 1 to 4.
Eloka
Two to 4 in cluster. Medium sized nut with clean kernels in open husks.
No. 500
Four to 10 nuts in cluster. Has short open husk. Good-sized nut ofBarcelona type. Is a good cropper of clean kernels. Shell heavy.
No. 502
Largest Barcelona type Filazel that has fruited to date. Clusters contain 4 to 8 nuts enclosed in heavy medium-length closed husks.
No. 503
One to 9 nuts in cluster, having clean, full kernels in thick shells enclosed in short open husks.
No. 505
One to 6 nuts in cluster, having closed, medium length husks. A good cropper.
No. 509
Two to 6 roundish nuts in long closed husks free of prickles so common on wild hazels. A good cropper. The parent hazels used for these crosses mature the nuts by the first of August and were winter hardy at-60° F. in Peace River, Alberta.
Other Hazels
Manchurian short bush hazel, distinctive clipped off top on leaf with some colored (of reddish hue). This bush retains leaves all winter, and would make a good protective covering for wild life. Has well-flavored, clean kernels fully developed by August seventh, 1950. Kernel is enclosed in heavy, squat shells encircled with distinctive short closed husk, as if folded together just covering nut. The leaf shape and markings carry through and appear in the young seedlings.
Experiments with Tree Hazels and Chestnuts
Corylus jacquemontii
(Smooth Bark) India Tree Hazel
Tree No. 1. Location—N.W. corner Lot 6, subdivision Lot 487, Scions from Kew Botanical Garden, England. Top grafted on Craig filbert 10 feet from ground line. This made good annual growth and compatibly well adjusted unions, which after many years are still in line and not readily detected except by difference in color and character of bark—the grafted top being smooth and lighter of color than Craig stock. Although stocks were bearing when cut for grafting, and scions were from bearing trees and had catkins on when received, grafts were trained to take over and become the main growth and leading tree from the Craig crown. This grafted tree did not produce catkins or nuts for four or five years, but branches on the stock went right on bearing, as did also other Craig sections on same root crown or filbert clump used for grafting above tree hazel. At date of writing, and following the severest winter of the past 45 years, when temperatures dropped to -24° F., followed by brief, bright sunshine and rapid rise of temperature, all ungrafted filberts of over three to four inches in diameter are dead or nearly so, while suckers 2-1/2 inches in diameter and smaller are quite sound and making good growth. So, also, are the stocks or sections top grafted to the tree hazel—even the larger 4 to 4-1/2 inches in diameter trunks. I ask why, as by all ordinary results the grafted trees should have been the easiest damaged. This tree, and the other sections of filberts on same crown, had cropped for three years past, so that from that angle they should have been on an equal footing. Only a few clusters of nuts grew on this ~Corylus jacquemontii~ this 1950 season.
Data on tree size: Height 32 feet—was grafted about 10 feet above ground line. Circumference of tree—12 inches above ground is 15 inches. At 4 inches below the graft, it is 10 inches, and the same four inches above graft union, which is very uniform, and if this combination could be reversed we would have an ideal non-suckering stock for commercial filbert orchards. ~Jacquemontii~ also buds well on cork bark ~C. colurna~ tree hazel.
Corylus jacquemontiiSmooth Bark India Tree Hazel onCork Bark Turkish Tree Hazel
Corylus colurna Stock
Tree No. 2 Location—S.W. corner of Lot 6, subdivision Lot 487. Budded August 15, 1941, at six feet from ground line, to one inch two year growth. Two years later top was removed and bud made to take over leadership. From then on it made good growth. Removal of top was not done at one operation, but first year leader was cut one-third way through, on long slope from bud downward on both sides, and allowed to callus over one year. Second year leader was cut further and when callused, top was then removed. This treatment gave good coverage of wound on trunk. Tree bore first crop 1949, eight years after budding. Nuts 1/2 inch in diameter, moderate shell of roundish form, well filled, with good flavor, clean kernels. August 4, 1950—Tree has a base circumference at ten inches above ground of 18-1/2 inches—at six feet above, 14 inches—below union circumference is 14 inches, while four inches above union it is 11 inches. No evidence of any winter injury after taking a-24° F. temperature. No crop this year, but has a good crop of catkins showing for 1951.