214 Pflanzenkrankheiten. — Bryophyten. 



Barley, rye, and Bromus tectorum have been infected by all 

 six biologic forms. Oats have been infected by all but P g. tritici 

 compacti, but not enough trials have been made with this form. 



All gradations in susceptibility occur, from complete immunity 

 to complete susceptibility to various biologic forms. The following 

 reactions may be made to inoculation : No visible effect; appea- 

 rance of small flecks; production of very minute uredinia without 

 any flecks; production of minute uredinia in either small or large 

 dead areas; development of moderateljT- large uredinia in small, 

 medium or large flecks; production of large uredinia surrounded 

 by small dead areas or by apparently healthy tissue. 



The biologic forms can be distinguished from each other mor- 

 phologically as well as parasiticall3\ The sizc, shape, and color of 

 the urediniospores are the distinguishing characters. The deter- 

 mination of biometrical modes permits identification with a reason- 

 able degree of certainty if the spores measured have been developed 

 under approximately similar conditions. 



The rate of development of a given biologic form depends on 

 the vigor of the rust strain, the kind, and sometimes the age of 

 the host plant, the amount of light, heat and humidity. Sunlight, 

 high relative humidity, and moderate temperatures, up to about 

 75° F., are favorable to rust development. 



Preliminary observations were made on the overwintering of 

 the uredinial stage on grass hosts, but definite conclusions have 

 not been reached, except for P. g. phleipratensis, which survived 

 the very severe winter of 1916 — 17 at St. Paul, Minn., very easily. 



There is evidence to show that grasses often rust in the 

 spring or early summer before rust appears in grain fields in the 

 same vicinity. This is especially true if grasses are near barberries. 

 The rust thus developed early in the season has usually been the 

 rye and wheat stemmst forms. 



Inconceivably large numbers of urediniospores are produced 

 by various grasses in cereal-growing regions. Unquestionably, 

 therefore, grasses are very important in increasing the amount of 

 infective material and in this way, if in no other, they are impor- 

 tant in the cereal rust problem. M. J. Sirks (Wageningen). 



Weir, J. R., A needle blight of Douglas Fir. (Journ. agric. 

 Research. X. p. 99—103. Washington, 1917.) 



Attention is drawn to a needle blight, that has caused for the 

 past three seasons great damage to young trees and seedlings of 

 Douglas Fir {Pseudotsuga taxifolia (Lam.) Britton) in the Northwest. 

 The systematic position of the causal fungus has not been satisfac- 

 torily determined, but it is referred for the present to the Stictida- 

 ceae. The fungus is virgorously parasitic and is apparently confined 

 to the Douglas Fir. Is has been found throughout the entire North- 

 west. Spraying with a Solution of soap and Bordeaux mixture 

 (4 — 4—50) gives indication of being a successful means of Control- 

 ling the fungus. M. J. Sirks (Wageningen). 



Benedict, Ch., Ein Fall der Haubenbildung auf dem Spo- 

 rogon des Lebermooses Aneiira pinguis (L.) Dum. (Notizbl. 

 Kgl. Bot. Gartens Berlin-Dahlem. N" 63. VII. p. 78-80. 1917.) 



Verfasserin fand im Herb. v. Flotow eine Kapsel von Aneura 



