Part 32 (1/2)

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.