756 



SCIENCE 



[N. S. Vol. XXXI. No. 802 



Studies on the Club Boot of Cabbage: Dr. Howard 

 S. Reed, Virginia Agricultural Experiment Sta- 

 tion. (Read by title.) 



The Curly Top Disease of Sugar Beets: Mr. 

 Hakby B. Shaw, Bureau of Plant Industry. 

 (Read by Mr. W. A. Orton.) 

 The various names by which the disease is 

 known are briefly referred to, then follows a 

 description of the symptoms observed to be char- 

 acteristic of it. The fact that the resisting power 

 of the beet varies according to the size of the 

 latter is referred to. 



The most important theories as to the cause of 

 curly top are mentioned, together with a review 

 of the writer's experiments covering many of the 

 theories set forth. 



Certain experiments with leaf hoppers com- 

 monly found on the beet, and the fact that the 

 leaf hopper, Eutettix tenella Baker, is the pri- 

 mary cause of curly top in beets, is recited. 



Observations were made to the effect that curly 

 top disease may develop in beets planted for seed 

 production the second season although no symp- 

 toms of the disease were visible when those beets 

 were harvested the preceding fall. This was dem- 

 onstrated to be the case, and experiments estab- 

 lishing this fact are described. This renders the 

 disease a double menace to the production of beet 

 seed. 



Four Years' Results in Selection for a Disease- 

 resistant Clover: Professor S. M. Bain and 

 Mr. S. H. EssARY, Tennessee College of Agri- 

 culture and Experiment Station. 

 The announcement was made by the authors in 

 1906 of the marked resistance shown by the 

 progeny of select clover plants to the Colleto- 

 trichum disease occurring in Tennessee. This 

 resistance has been maintained under various 

 cultural and laboratory conditions for five suc- 

 cessive generations, and there no longer exists 

 any doubt as to the economic value of the strain 

 being propagated. There will be about fifty acres 

 grown in the seed crop during the season of 1910. 

 The indications are that a naturalized strain 

 was found in the original selections. The resist- 

 ance shown to the anthracnose is probably due to 

 acclimatization, and is, therefore, not specific. 

 An outbreak of rust in 1908 brought out indica- 

 tions of rust resistance also. 



A Fungus Enemy of Mushroom Growing: Mrs. 

 Flora W. Patterson, Bureau of Plant In- 

 dustry. 

 The paper relates to the first occurrence of 



Uycogone perniciosa Magnus in American mush- 

 room beds. The fungus was identified by the 

 author in several collections received from mush- 

 room beds in Pennsylvania during March, 1909. 

 The disease caused by this fungus has long been 

 recognized as a serious one by growers in England 

 and on the continent. The parasite is variously 

 referred to by writers as Mycogone perniciosa 

 Magnus and Hypomyces perniciosus Magnus. The 

 latter name was previously given it by Magnus 

 in 1887, who, however, did not describe the per- 

 fect stage, but reasoning from analogy, inferred 

 it would be found in the genus Eypomyces. Two 

 conidial stages, a Verticillium sp. and Mycogone 

 perniciosa, have been identified in the American 

 material, and it is hoped that the perfect stage 

 may develop in cultures that are being kept under 

 observation. 



European Currant Rust on White Pine in Amer- 

 ica: Dr. Perley Spaulding, Bureau of Plant 

 Industry. 



The European currant rust has two stages: 

 one as Peridium strobi on the white pine, the 

 other as Cronartium ribicola upon leaves of Ribes. 

 The fungus is native in eastern Europe upon 

 Pinus cembra, upon which it usually does little 

 damage. Since about 1860 it has attacked Pinus 

 strobus, P. monticola and P. lambertiana, all 

 American species of five-leaved pines. At present 

 it is distributed throughout Europe, and is 

 causing great damage to white pines in certain 

 sections. In the spring of 1909 it was imported 

 into the United States upon about two and a 

 half million young white pine trees, being dis- 

 tributed in the states of New York, Vermont, 

 New Hampshire, Massachusetts, Connecticut and 

 Pennsylvania. Lots of trees from the same nur- 

 sery are also known to have been imported into 

 Ontario and Minnesota. During the past summer 

 a special effort was made to remove the Ribes 

 from the vicinity of these plantations, and, it is 

 believed, successfully, except in portions of Con- 

 necticut and in Ontario and Minnesota, which 

 latter are to be inspected by local authorities. 

 This work was carried on in cooperation with the 

 forestry and plant pathological workers of the 

 states involved. The National Department of 

 Agriculture has absolutely no power to prohibit 

 importing, or to inspect, condemn or destroy such 

 imported stock, except by courtesy of the owner. 

 The situation is especially serious should the 

 importation continue in future years upon the 

 same scale as during the last year. Immediate 

 action should be taken by the various states in- 



