From these early plantings we learned that (1) Asiatic chestnuts and hybrids are more likely to develop into forest trees when planted on cool, moist, fertile situations; (2) in their silvicultural characteristics they are more nearly like our native yellow-poplar, northern red oak, and white ash, than like our American chestnut and native chinkapins; (3) with respect to tolerance of shade, they are much like our northern red oak; and (4) neither the Chinese nor the Japanese chestnut has quite the same forest-type growth as that of our native American chestnut.

With this background of experience, the U. S. Division of Forest Pathology from 1936 to 1939 established a series of 21 climatic test plots on above-average sites on Federal- and State-owned forest land in eight Eastern States. Fortunately, we still had available suitable planting stock of the many kinds of chestnut, chinkapins, and hybrids for conducting such an extensive test. At this point we should also mention that from 1947 to date, the Division of Forest Pathology, in cooperation with the Connecticut Agricultural Experiment Station, also established 11 hybrid test plots in Arkansas, Connecticut, Illinois, Michigan, Ohio, Pennsylvania, South Carolina, Tennessee, and West Virginia. In 1930 the Brooklyn Botanic Garden also began breeding blight-resistant chestnuts of timber type, and in 1947 transferred this project to the Connecticut Agricultural Experiment Station.

The 21 climatic test plots ranged from one to two acres each, and were planted with more than 20 progenies represented, as well as forest-tree chinkapin and some hybrids. Nearly all of the 21 climatic test plots were fenced against deer and domestic livestock. The 11 hybrid test plots, approximately 1/4 acre each, were planted with 100 hybrids (50 furnished by each of the two agencies), and 50 Chinese chestnuts—P.I. 58602, the most outstanding Chinese chestnut from the forestry standpoint, thus far discovered. The climatic test plots were established on freshly cleared forest sites, with trees randomized, and planted 8 feet apart. In the hybrid test plots, the seedlings were planted under forest growth and the overstory trees were girdled; the seedlings were randomized in these plots, with spacing of 10 by 10 feet.

The 1- to 6-year period of testing for the hybrid chestnut, and the 14- to 17-year period of testing of the chestnuts planted in the climatic test plots are too short for final judgment of performance; however, certain characteristics are appearing with reference to blight resistance, winter hardiness, timber-tree form, early fruiting, and rate of growth. The present paper does not attempt to summarize all of the data obtained from all these climatic plots but rather to point out some striking results obtained from several widely separated climatic plots. Results from the hybrid test plots are not included in this discussion.

Discussion

A performance rating of 28 chestnuts, chestnut hybrids, and forest-tree chinkapins, tested in forest plantings for 12 to 13 years in Indiana, Iowa, North Carolina, and Pennsylvania showed that certain kinds always produce better trees than others. P.I. 58602 is the best Chinese chestnut tested thus far, as determined by performance in the above-mentioned test plots and in several plantations established in 1926. In the Middle Western States, all Japanese chestnuts, Henry (forest-tree) chinkapins, and the "ever-blooming" Sequin chestnuts have shown poor growth or have died. They do not appear to be winter hardy.

On the basis of these findings, the Division of Forest Pathology since 1946, has made available to Federal and State agencies only one introduction of Chinese chestnut—P.I. 58602—for planting as forest trees. They were distributed in lots of 50 trees, and used to establish 1/4-acre demonstration forest plots. All are located on public-owned land on favorable forest sites where Asiatic chestnuts would be expected to do well. The underplanting-and-girdling method was recommended in the establishment of all the plots.

Chinese chestnut P.I. 58602, because of its superiority in performance as a forest tree, is now also being used extensively at Beltsville, Maryland, in hybridizing work. Nearly all of the Japanese chestnut, Henry chinkapin, and Sequin chestnuts, as well as inferior hybrids in the climatic test plots during the past several years have died a natural death or have been destroyed. They have been replaced with Chinese chestnut (P.I. 58602) replants—thus gradually converting the climatic test plots into future Chinese chestnut "seed" plots of the very best Chinese chestnuts.

During the spring of 1953 several nurserymen members of the Northern Nut Growers' Association furnished the Division of Forest Pathology a total of 2,600 Chinese chestnut seedlings for tests to determine their suitability for forest planting. These and 600 seedlings of Chinese chestnut P.I. 58602 are now being tested for performance, in randomized plots, on favorable forest sites in North Carolina, Ohio, and Illinois.

Conclusions