146 ANNUAL KEP0ET3 OF DEPARTMENT OF AGEICULTURE. 



only under quarantine greenhouse conditions at Washington. This 

 experimental work, however, is now being financed from the allot- 

 ment for Fruit-Disease Investigations. 



BiTTER-KOT OVERWINTERING. — During the past year spraying experi- 

 ments for the control of apple blotch and apple bitter-rot by various 

 fungicides have been continued. The special feature of this work 

 has been the discovery of the overwintering of the bitter-rot fungus 

 on various small and minor cankers and on cankers and injuries 

 produced by other causes, and the demonstration that when these are 

 removed full control of bitter-rot can be obtained. 



White-pine blister rust. — The work of eradicating the white-pine 

 blister rust has proceeded as heretofore, by assisting the State author- 

 ities in positive identification of the disease in questionable cases, 

 by helloing eradication efforts by personal examinations and sugges- 

 tions as to the most efficient methods, and by urging State officials 

 to a uniform and efficient general policy. One new outbreak of the 

 disease was discovered in a plantation of 50,000 nine-year-old trees. 

 At the request of the State officials, the diseased area was examined 

 and recommendations were made, which were followed in destroying 

 all the pines and many wild Eibes of the vicinity upon which the 

 disease passes one stage of its existence. A similar request from the 

 Dominion authorities of Canada was answered by a personal ex- 

 amination of the area and advice given as to the most efficient 

 methods to use. The total destruction of infected lots of white pines 

 is becoming recognized as desirable, and a strong public opinion is 

 developing in favor of it. 



Cotton diseases. — Cooperative breeding and dissemination of dis- 

 ease-resistant cotton and cowpeas in South Carolina, Georgia, and 

 Alabama have been continued. In South Carolina thirteen coopera- 

 tive breeders and twenty-three cooperative growers planted 579 acres 

 of wilt-resistant cotton and produced 5,005 bushels of select seed for 

 sale. In Georgia thirty cooperative breeders and five cooperative 

 growers produced C,750 bushels of wilt-resistant cotton seed for sale. 



Flax canker. — In the study of flax diseases an effort has been made 

 to determine the cause of flax canker, a troublesome disease in flax- 

 growing sections west of the Missouri Kiver. The attempts to isolate 

 a fungus thought by some to be the cause have thus far given negative 

 results. In the study of the flax wilt organism field plat experiments 

 and laboratory experiments have been conducted to determine the 

 physiology of infection. 



Cereal rusts. — Additional data on rust-resistant hybrids have 

 been accumulated and emphasis has been placed on determining the 

 relation of growth factors to rust epidemics and special work has 

 been undertaken at Akron, Colo., on this project. Extensive milling 

 and baking tests have been inaugurated with several rust-resistant 

 spring- wheat hybrids grown at St. Paul, Minn. 



Cereal smuts. — A careful experimental study is being made rela- 

 tive to the control of infection by the loose smuts of wheat and bar- 

 ley and some progress has been made in developing a means of pre- 

 vention. Methods for the prevention of bunt, covered smut of bar- 

 ley, and oat smut are being tested. Important data have been 



