Northern Nut Growers Association Report of the Proceedings at the 41st Annual Meeting Part 32

In southern Connecticut the 1950 season for vegetative growth and development was excellent except for the dry period in September. The chief fault lay in much more cloudy weather than usual,[31] and the deficiency in sunlight coupled with a slightly lower average temperature in the spring, and cool nights, combined to delay the chestnut flowering season for as much as ten days. The main body of our cross pollination experiments did not begin until July 4, whereas last year it began on June 23 and 24, and was nearly completed by July 4.

[31] For example, the report of the U. S. Weather Bureau at New Haven, Conn., for May, 1950, says, "The feature of the month was the lack of suns.h.i.+ne which r.e.t.a.r.ded the growth of crops in this area." See also report of the New York City Station for April, 1950.

This year 103 crosses were made, not all different combinations, but each one with either different or reciprocal parents. The princ.i.p.al combination was a cross of j.a.panese chestnut with Chinese-American or American-Chinese, a mixture that in recent years has given excellent results. This year also, as in the past, our CJA's were crossed with American chestnut.

[Ill.u.s.tration: Fig. 1. Cross pollinating Chinese chestnuts. Sleeping Giant Plantation, Hamden, Conn. Trees near left of center and at left, with drooping catkins, are j.a.panese-American hybrids. Photo July 13, 1950, by B. W. McFarland.]

~Cooperation with Italy.~ A considerable part of the cross pollination work this year has been undertaken for the benefit of the Italian authorities, namely experiment stations at Florence and Rome. This has been done at the suggestion of the Division of Forest Pathology, Beltsville, Md., which has been working along the same line.

As is now generally known, the chestnut blight was discovered in Italy in 1938, and has been making rapid headway in a country 15 percent of whose forests are in chestnut. To the Italians the chestnut means much as an article of food. They use the timber also, and the various ages of coppice growth in many ways[32]. Particular effort this year has been directed toward the breeding of promising nut-bearing types for them and especially resistant strains that bear large nuts like the cultivated European chestnut.

[32] Graves, Arthur Harmount. Breeding Chestnut Trees: Report for 1946 and 1947. 38th Ann. Rept. Northern Nut Growers a.s.sn. p. 85. 1947.

Now, we have found that many of our Chinese chestnuts are practically immune to the blight. Even if the disease does appear, in most cases it is in the outer bark only, and is soon healed over. Moreover, the Chinese chestnut has a large nut, comparable in size to the cultivated Europeans with pollen from our best Chinese trees, and at the same successful crosses of the European and Chinese are made.

Last fall, as a result of an article in the _New Haven Register_ by Mr.

A. V. Sizer, I learned of two European chestnut trees of bearing age in New Haven back yards. So, this summer we have crossed these Europeans with pollen from our best Chinese trees, and at the same time have taken the pollen from one of them (in the other the pollen was sterile) and applied it to the female flowers of our Chinese trees. Most of the resulting nuts have been sent to the Italian scientists in the hope that some of them will develop into desirable nut-producing, disease-resistant hybrids. Some will be retained for testing here. If the resulting trees are not sufficiently blight-resistant, they will be crossed again with the Chinese.

In the summer we received by air mail from Dr. Aldo Pavari, of the _Stazione Sperimentale di Selvicoltura_ in Florence, Italy, two tubes of pollen of the European chestnut, _Castanea sativa_, of the varieties _pistolese_ and _selvatico_. These pollens were also applied to our best Chinese trees. They resulted in 12 good nuts which have been s.h.i.+pped to Dr. Pavari.

Further, we have on our Sleeping Giant Plantation, Hamden, Conn., several hybrids, now 16 years old, of the Seguin and the Chinese chestnuts, the former species being also a native of China, but dwarf and everblooming and remarkably prolific. These hybrids are excellent as nut producers, since they inherit the large-sized nut of the mollissima parent, combined with the increased productivity of the Seguin parent.

Furthermore they are extremely blight-resistant.[33] These hybrids have therefore been intercrossed among themselves this year, chiefly for the benefit of the Italian people. One hundred and eight nuts from reciprocal crosses of these hybrids were s.h.i.+pped to Italy. Also, in response to a request, we sent nuts of our best Chinese and j.a.panese trees and of the _mollissima-seguini_ hybrids to M. C. Schad of the _Station d'Amelioration du Chataignier_, Clermont-Ferrand, France.

[33] These hybrids will shortly be put on the market, under the sponsors.h.i.+p of the Conn. Agr. Expt. Sta. and the Division of Forest Pathology, U.S.D.A. As regards the everblooming habit of the Seguin parent, that character seems to be lost or at least partly suppressed. A second flowering of one of the hybrids usually occurs in August.

~Other crosses.~ Two Chinese-American trees in our plantation at the White Memorial Foundation near Litchfield, Conn., bore a considerable number of female flowers this year for the first time. They have been crossed with the fine j.a.panese tree of Mr. A. N. Sheriff at Ches.h.i.+re, Conn., figured in my report for 1948-49. (P. 92, fig. 3, of 40th Rept. of N.N.G.A.) From them, 75 nuts were harvested of the combination CAxJ.

Four crosses were made on the trees at Redding Ridge, Conn., in the cooperative plantation of Mr. Archer M. Huntington, resulting in 73 nuts. Also, the resistant Americans on Painter Hill, Roxbury, Conn., were again crossed with CJA's and Chinese from our Sleeping Giant Plantation and from these were obtained 247 nuts. Finally, we have this year succeeded in making a cross between _Castanea henryi_, the Henry Timber c.h.i.n.kapin from southern and central China, which is said to attain a height of 90 feet, and _C. mollissima_, the Chinese chestnut.

Since _henryi_ blooms very early, much before our _mollissima_, the Division of Forest Pathology mailed us pollen of _C. mollissima_, which reached us just in time to be applied to _henryi_. Seven good nuts of this cross were gathered.

Altogether, as the overall result of our cross pollination work, we harvested 1259 nuts, more than twice as many as obtained in any other year since we began this work in 1930.

------------------------------------------------------ TABLE 1

Heights of Some of Largest Trees, as of Oct. 1, 1950.

All at Sleeping Giant Plantation, Hamden, Conn.

Species or Height Hybrid Location Age in yrs. in ft. Remarks ----------------------------------------------------------------------- J A Row 4 Tree 10 19 30 Repeatedly inarched J A " 4 " 4 14 33 Grafted on j.a.p.

stock, Apr. 1937 J A " 4 " 12 19 29 Repeatedly inarched J " 7 " 5 20 23 C " 1 " 4 24 30-3/4 CJA " 60 " 39 13 29 CJA " 61 " 48 13 24 CJA " 8 " 8 4 14 Grafted on Chinese stock, spring, 1947.

Fruited this yr.

1st time.

------------------------------------------------------------------------ J=_Castanea crenata_ A=_Castanea dentata_ C=_Castanea mollissima_

~Nuts, Scions and Pollen Received.~ During the fall of 1949 we received nuts from New Hamps.h.i.+re, Ma.s.s., Conn., N. Y., N. J., W. Va., N. C., Ohio, and Ill. Scions were received in March and April from Mr. R. M.

Viggars of the Bartlett Tree Expert Co. station at Wilmington, Del. (_C.

dentata_); and from Messieurs Schad and G. A. Solignat, _Centre de Recherches Agronomiques_, Clermont-Ferrand, France, (_C. crenata_ and _sativa_.) During June and July, pollen of _C. dentata_ came from Mr. E.

J. Gra.s.smann, Elizabeth, N. J., Mr. Paul Maxey, Montcoal, W. Va., Mr.

Malcolm G. Edwards, Asheville, N. C.; _C. mollissima_ and _dentata_ from the Division of Pathology, U.S.D.A.; _C. sativa_, vars. _pistolese_ and _selvatico_ from Dr. Aldo Pavari, _Stazione Sperimentale di Selvicolture,_ Florence, Italy; and _C. pumila_ and _dentata_ from Mr.

Alfred Szego, Flus.h.i.+ng, N. Y. This list is presented as evidence of the widespread interest in our work. It is a pleasure to acknowledge this cooperation and to thank the many donors. We are especially glad to report that several "catches" have been made with the C. sativa scions from France and those of the tall _mollissimas_ at Mt. Cuba, Del., from Mr. Viggars.

May I again caution those who send us nuts not to allow them to become dried out. The embryos, when dried, are killed. The nuts should be wrapped in moist cotton, peat moss, or something similar, and mailed to me not later than a few days after harvesting, at 255 South Main Street, Wallingford, Conn.

~Insects, bad and good.~ The cankerworms were rather destructive in May at our Sleeping Giant Plantation (not at the others) but fortunately later than usual. The mite, _Paratetranychus bicolor_, attacked the leaves of some of the trees on the Sleeping Giant Plantation rather late in the season, so that on September 8 we sprayed with the Station's power sprayer, using Aramite effectively. Shade and humidity seem to favor the spread of this pest. j.a.panese beetles appeared but have never been very destructive with us. As happened last year, we sprayed twice for the weevils, August 14 and September 8, with excellent results.

This spring in early June, four hives of bees were placed in one of our Sleeping Giant Plantations by bee experts of the staff of the Conn.

Expt. Station. Improved results in pollination and the resulting nut harvest cannot be affirmed with only one season's trial.

A Method of Controlling the Chestnut Blight on Partially Resistant Species and Hybrids of Castanea

ARTHUR HARMOUNT GRAVES Connecticut Agricultural Experiment Station, New Haven and Division of Forest Pathology, U.S.D.A. Plant Industry Station, Beltsville, Maryland

This method has been in use since 1937 on our chestnut plantations, and has been so remarkably successful that we believe all chestnut growers should be thoroughly acquainted with it.

[Ill.u.s.tration: Fig. 1.]

Whenever chestnut trees are attacked by the blight fungus, suckers arise below the lesion, and if the lesion is at or near the base of the tree, as often happens, these suckers grow from the base of the tree, i.e. at the root collar. It is then a simple matter to cut out the diseased bark of the lesion with a sharp knife, paint over the wound, and graft the tip of one or more of these suckers _above_ the lesion, into the healthy bark. Of course the sucker must be long enough to reach the healthy part of the bark above the lesion. It is measured roughly by the eye and then cut off at a proper length, usually a little longer than seems necessary. The tip is then sharpened into two beveled surfaces coming up to a thin sharp transverse edge like a long wedge. (Fig. 1a.) The tip edge must be very sharp in order to push up easily between the bark and wood. Now, or rather, before tr.i.m.m.i.n.g the sucker, in the healthy bark above the blight lesion cut an inverted T, making the cut into the bark as far as the wood and then cut a gradual slope from the surface of the bark down to the horizontal part of the inverted T. Next, lift the bark gently from the wood above the horizontal cut and insert the end of the sucker. If the sucker, or scion, is slightly longer than the upper end of the cut, it can be bent outward at the same time that the scion is being inserted and thus a spring is secured making it easier to force the scion up between bark and wood. I should add that if the lesion is not at the base of the tree, suckers usually arise just below it in any case, and these can be inarched in the same way as the basal shoots.

[Ill.u.s.tration: Fig. 2

Fig. 2 Showing inarching method of controlling the chestnut blight a Chinese-j.a.panese hybrid chestnut, 13 yrs. old, infected toward base with Chinese type of blight, i.e. in outer bark only. Right: sucker inarched in spring of 1946; left, inarched spring of 1950. (The black figure resembling an arrow, about half way up, is accidental, being a cl.u.s.ter of labels.) b. Grafted tree (the large tree of j.a.panese-American chestnut on j.a.panese stock); graft made in 1937 where finger is pointing; left: inarch of 1947, itself inarched near base in 1950; right, inarch of 1949. c. j.a.panese-American hybrid chestnut with princ.i.p.al inarch made in 1943; other later inarchings showing in part.

All photos by Louis Buhle, Brooklyn Botanic Garden, and loaned courtesy of the Garden.]

The next step is to bind together the parts being grafted, winding strong, cotton string firmly around the cut with its scion enclosed, covering practically all of the vertical cut of the inverted T. Finally, melted paraffin--not too hot--is applied to the union, every part being carefully covered in order to exclude air and thus prevent drying out.

We use Clarke's melter which, with adjustment of the flame, will keep the paraffin at a temperature slightly above the melting point and thus will not get too hot. Grafting wax may also be used instead of paraffin.

The best time to perform the operation in Connecticut is during April or early May.

Our first scions or inarches, grafted in 1937, are now 6 inches in diameter at ground level and const.i.tute the main tree. If they become blighted, other suckers are inarched into them, and so on. The purpose of the inarching is to restore the communication between leaves and roots, which is so essential to the life and health of the tree, and which the diseased bark of the blight lesion interrupts, eventually causing girdling and death of the trunk or branch attacked. A series of these inarchings of different ages is shown herewith. (Fig. 2.) On our plantations we no longer dread the chestnut blight, since we can usually circ.u.mvent it by this method. However, with the American chestnut, because the fungus advances rapidly in this species, the girdling is often completed before the scions can take hold. Therefore, with that species or with the least resistant hybrids the method is often though not always ineffectual.

This method of grafting is not new. It is similar to bridge grafting and has been known and practiced for centuries. The only credit we can claim is for its application to the chestnut blight as a method of control.

MR. CHASE: We will now hear from Mr. George Salzer, Rochester, New York, "Experiences with Chestnuts in Nursery and Orchard in Western New York."

Mr. Salzer.

Experiences with Chestnuts in Nursery and Orchard in Western New York

GEORGE SALZER, Rochester, New York

My work with Chinese chestnut trees during the past ten years has been most interesting. The first trees were grown in our back-yard garden; then, when more seed was available locally, a building lot was purchased for use as a nursery. Seed is planted in the spring because when fall planting was tried, the rodents took most of the nuts.