BUREAU OF PLANT INDUSTRY. 79 



NUT-PROPAGATION EXPERIMENTS. 



In an effort to discover some practicable nnrsery method of propa- 

 gating walnuts and hickoi-ies in the Middle and Northern States, cer- 

 tain experiments in greenhouse propagation were undertaken with 

 the Persian walnut, the pecan, and two species of hickory. 



The essential feature ot these experiments, which were planned and 

 carried on by Mr. William P. Corsa, of this office, consisted in the 

 control of conditions of temperature and humidity during the period 

 when the newly set grafts were undergoing the callusing process. At 

 the same time special precautions were taken to protect the newlj^ 

 grafted trees from injury by certain insects and fungi which thrive at 

 the relatively high temperature considered necessary for successful 

 callusing of these species. 



The stocks used were mainly one-year-old seedling trees, and sev- 

 eral allied species were tested under similar conditions for each kind 

 of scion used. These were planted in pots after being grafted and 

 callused, and were permitted to start and continue in growth until 

 the climatic conditions warranted their transplanting to the open 

 ground in early May. Tip to this point the results obtained were, on 

 the whole, encouraging. Later developments in the open ground con- 

 siderably reduced the proportion of successful grafts, apparently 

 through the destructive effect of the intense heat of the sun upon the 

 newly planted grafted ti'ees. 



The experience gained in these experiments will be utilized in future 

 work along similar lines, as the subject is considered one of great 

 importance in view of the growing interest in nut culture in the 

 United States. 



CARD CATALOGUE. 



The work on the card catalogue of fruits has been continued during 

 the year by Prof. W. H. Ragan, who has it in charge. 



The varieties of the important tree fruits and grapes in the stand- 

 ard pomological works published in America having been catalogued, 

 the listing of such varieties as have been listed or described only in 

 nursery catalogues, horticultural periodicals, horticultural society 

 reports, and similar publications has now been taken up. 



EXHIBIT AT THE PAN-AMERICAN EXPOSITION. 



The exhibit prepared for the Pan-American Exposition by tlie office 

 consisted of four distinct features: 



(1) A comprehensive collection of fruit models, illustrating the more 

 important varieties of the several fruits grown in the United States. 

 This consisted of more than 1,000 specimens, representing about 850 

 named varieties belonging to 62 distinct botanical species. 



(2) An exhibit illustrating the standard commercial grades of apples 

 as adopted by the National Ai)ple Shippers' Association and now gen- 

 erally recognized throughout this country and Canada in commercial 

 transactions in this important fruit. 



(3) A collection of named varieties of pecans from the Gulf States. 



(4) A collection of photographs illustrating certain characteristic 

 features of the horticulture of the United States. 



As the material for this exhibit is drawn largely from the working 

 collections of the office, and as the work of preparation and instal- 



