752 



SCIENCE 



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



The above experiments were duplicated with 

 series of experiments in Van Tigheim cells, which 

 gave more accurate results on germination of 

 spores, maximum growths and formation of new 

 spores. 



A series of experiments was made to compare 

 the growth of organisms in media in which the 

 proteid and tannin formed a precipitate and in 

 media in which proteid was not used. 



A series of experiments was made to show 

 relative resistance of cork from which the tannin 

 had been extracted and cork soaked with tannin 

 of various percentages. 



Parasitism of Coryneum foliicolum and Phoma 



mali Schulz et Saeo. : Dr. Chaeles E. Lewis. 



Maine Agricultural Experiment Station. 



Coryneum foliicolum Fckl. has been reported as 

 common on dead spots in living leaves of the 

 apple, but in this investigation it has been found 

 also in cankers on the branches. The fungus has 

 been grown in pure culture on a number of cul- 

 ture media and inoculations have been made on 

 leaves, wood and fruit of the apple. In confirma- 

 tion of the work of others, it is reported that 

 this fungus does not cause leaf-spot, but in this 

 study it has been found capable of doing great 

 damage to young apple trees and to small branches 

 of older trees by causing cankers which may 

 girdle the branch, killing the parts above the 

 girdled region. 



Phoma mali Schulz et Sace. has been isolated 

 from leaf-spot, canker, and decaying fruit of the 

 apple. This fungus does not cause leaf-spot, but 

 it can attack the wood of young apple trees and 

 branches of old trees. 



Both of these fungi have been tested as to their 

 ability to cause decay of apples. Coryneum causes 

 a small amount of decay in ripe fruit. Phoma 

 causes a rapid and complete decay of ripe fruit 

 and can attack green apples to a slight extent. 



Lettuce Selerotiniose : Dr. F. L. Stevens and Mr. 

 J. G. Hall, North Carolina College of Agricul- 

 ture and Mechanic Arts. 



A brief summary is presented of some of the 

 experimental results of several years' study of 

 lettuce selerotiniose. The expansion of the let- 

 tuce industry and the history of this disease are 

 mentioned. The results of a statistical study of 

 spores from apothecia of different ages is pre- 

 sented, also of physiological studies concerning 

 the temperature relations of the fungus, longevity 

 of the mycelium under various conditions, effects 

 of various nutrients and of alkalinity and acidity 



upon growth. The toxicity of various fungicides 

 was studied, also the effects of illumination, depth 

 of planting and stirring of the soil upon germina- 

 tion of sclerotia. The germination of ascospores 

 in various media was studied, also their longevity. 

 Special attention was given to the question of 

 parasitism and saprophytism and to determining 

 to what extent and under what conditions the 

 mycelium could migrate through or over soil. 

 The view is expressed that the ascospores and the 

 mycelium are both short lived, that the solero- 

 tium is the only long-lived structure and that 

 the prevention of formation of sclerotia by the 

 early destruction of effected plants constitutes a 

 promising means of eradication of this disease. 



Parasitism of Coniothyrium Fuckelii: Mr. P. J. 

 O'Gara, Bureau of Plant Industry. (Read by 

 title.) 



A Nero Hop Mildew: Dr. J. J. Davis. 



A downy mildew was observed on Humulus 

 lupulus in Wisconsin in 1909 which is referred 

 to Pseudopteronospora celtidis (Waite) Wilson as 

 var. Humuli n. var. and a description given. 



An Anthracnose of Red Clover caused by Glao- 

 sporium caulivorum Kirch. : Dr. H. E. Fulton, 

 Pennsylvania State College. 

 The characteristic lesions are elongated, sunken 

 areas on the stem, one centimeter or more long; 

 these have dark brown borders, with lighter cen- 

 ters over which the acervuli are scattered. Inocu- 

 lation tests indicate that infection takes place 

 most readily through wounds, or upon succulent 

 parts, or under very moist conditions. Under 

 field conditions the most serious outbreaks prob- 

 ably occur when continued warm showery weather 

 induces a very succulent type of growth. The 

 conidia were found to retain their vitality in one 

 instance for twelve months. Successful inocula- 

 tions were made on Trifolium pratense, T. pro- 

 tense var. perenne and T. hybridium. Unsuccess- 

 ful attempts were made to inoculate T. repens 

 and Medicago sativa. Rotation of crops, early 

 mowing of affected fields, the use of uncontam- 

 inated seed and the planting of resistant strains 

 of clover are suggested as control measures. 



Further Studies of Phytophthora infestans: Pro- 

 fessor L. R. Jones and Dr. B. F. Lutman, Ver- 

 mont Agricultural Experiment Station. 

 The authors, assisted by Mr. C. R. Orton, have 

 continued the work on Phytophthora infestans 

 reported at the meeting last year. The principal 

 advance has been made in the study of the resting 

 bodies and in the improvement and testing out 



