124 



Mycologia 



at Chicago, December 28-31, 1920, the following may be briefly 

 mentioned : 



" The regional occurrence of Puccinia graminis on barberry," by E. C. Stak- 

 nian, R. S. Kirby, and A. F. Thiel. 

 The common barberry does not rust in the Southern States and on the 

 Pacific Coast. It was found that barberries would not become infected in the 

 Southern States when they were inoculated with teliospore material which had 

 been developed in the South ; but when inoculated with teliospores from the 

 North, they became very heavily infected. Excellent infection was obtained 

 as early as March 16 by using northern material. Teliospores from the South 

 which had been kept in the North during the summer and fall, however, caused 

 infection in the South, while northern teliospores which had been kept in 

 the South did not cause infection. Teliospores formed in the fall in the 

 South caused infection in the following spring. Evidently, therefore, the rea- 

 son why barberries do not become infected in the South is not because con- 

 ditions are unfavorable for. infection, but because practically no teliospores 

 are viable in the spring. 



" The effect of incipient decay on the mechanical properties of airplane timber," 

 by Reginald H. Colley. 

 Standard tests conducted at the University of California by the Bureau of 

 Plant Industry in cooperation with the Forest Service indicate marked differ- 

 ences in the effect of different fungi on the mechanical properties of airplane 

 timber. Pieces of Sitka spruce and Douglas fir showing incipient decay were 

 tested against matched sound pieces. The effect of Fomes pinicola, Fomes 

 laricis, and Poly poms schweinitzii, which may be grouped together, was decid- 

 edly more marked than that of Trametes pini. Test sticks taken many feet 

 ahead of the typical rot showed the weakening effect of P. schweinitzii, while 

 sticks infected with T. pini gave as high or higher results than sound wood. 

 Lumbermen have long recognized that wood infected with T. pini is strong 

 even in the early pocket stage. Results point to need for more careful inspec- 

 tion and diagnosis of incipient decay in forest and mill to prevent the expense 

 of working and finishing defective stock and its inclusion in the airplane. 



" Valsa poplar canker," by Alfred H. W. Povah. 



This disease, under the name Cytospora chrysosperma (Pers.) Fr. has been 

 reported from the Southwest by Long and from the Northwest by Hubert. It 

 has been found near Syracuse, New York, to cause serious injury and in some 

 cases death to Populus tremuloides and P. grandidentata when weakened by 

 fire. Field studies show infection of 68.4 per cent and mortality of 36.9 per 

 cent. The perfect stage {Valsa sp.) has been found on the trunks of infected 

 trees. Inoculation experiments with pycnospores on cuttings of P. tremuloides, 

 P. grandidentata, and P. caroliniana have resulted in the production of typical 

 pycnia, bearing the characteristic red spore horns, and the death of the cut- 

 tings. Cuttings not inoculated but kept in the laboratory where material bear- 

 ing spore horns was exposed soon became infected and were killed. 



