896 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Crown gall. — The study of the crown-gall of orchard trees, small 

 fruits, and other plants has been continued, because of its economic 

 importance to orchardists, farmers, and nurserymen. 



The conclusions reached have been published in a bulletin recently 

 issued, the illustrations of which show graphically the advance which 

 has been made. The bacterial organism producing the disease, which 

 had been isolated repeatedly but never found microscopically in the 

 plant cells before, has now been demonstrated successfully. The in- 

 fectious nature of the organism isolated has been proved by hundreds 

 of inoculations, and many cross inoculations show its ability to pro- 

 duce galls on other plants than the one from which it was isolated. 

 As the bacterium is a soil organism which gets into the plants through 

 wounds due to careless grafting, borers, nematodes, etc., planters 

 should aim to keep their land free from it by refusing to plant in- 

 fected stock. Nurserymen should plant on uninfected land and care- 

 fully avoid heeling good stock into soil which previously received in- 

 fected plants. 



PATHOLOGICAL COLLECTIONS AND INSPECTION WORK. 



The work of the past year has continued under the supervision of 

 Mrs. Flora W. Patterson. 



Extent of the collections. — An inventory has been made show- 

 ing more than 60,000 specimens. The acquisitions include two rare 

 and valuable old sets of exsiccatse. About 300 permanent mounts 

 have been made from pure cultures and other interesting subjects. 



Many identifications have been made for the Office of Grain Stand- 

 ardization and the Bureau of Entomology, with a view to the 

 economic application of such information, and the work on soil 

 fungi or species possessing cellulose-destroying properties has re- 

 ceived attention. 



The constant demand for a semipopular bulletin for the identifi- 

 cation of common poisonous and edible mushrooms has been recog- 

 nized, and the preparation of such a publication is near completion. 



Inspection work. — The work of inspecting all suspected plants 

 which are introduced by the bureau is performed for the Offices of 

 Foreign Seed and Plant Introduction and of Crop Physiology and 

 is rendered more effectual by the extensive indexing of foreign and 

 domestic pathological and mycological literature, which provides 

 up-to-date information concerning diseases indigenous to localities 

 of prospective importations. 



FRUIT-DISEASE INVESTIGATIONS. 



The fruit-disease work of the bureau has continued in charge of 

 Mr. M. B. Waite. 



Work in California. — Work at Watsonville and other points in 

 California on the powdery mildew of the apple has made satisfac- 

 tory progress. The difficulty of preventing this disease by spraying 

 has led to important advances in the discovery and use of new fungi- 

 cides. Various diseases of the apricot, cherry, peach, and plum 

 have also been studied. 



