152 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



the structure of the sporophores and to Bcaiireria by the conidial 

 development. As to the latter the first couidiuni was formed at the 

 tip of a branch, while still in position, a second conidium budded out 

 from the hypha immediately below the terminal one. Five or six 

 conidia might thus be formed in succession. This growth character has 

 not, however, seemed to the author sufficient to separate the species from 

 the genus VerticilUum. 



Septorise on Ribes.* — R. E. Stone has made cultural experiments 

 Avith two species of Sepioria. The first, on R. nigrum, has for its perfect 

 form Mycosphaerella Grossularise. He has proved that the same fungus 

 ■attacks R. rubnim, R. Grossularia, and R. cynobasti ; it has also been 

 reported on R. prostratum, R. rotundifoUa, etc. The pycnidia are 

 mostly hypopliyllous on dark ashy-grey spots ; the perithecia, also 

 mainly hypophyllous, are gregarious on dead over-wintered leaves of 

 currant and gooseberry, and follow on the Septonia attack. 



8p.plo7iia mirea was similarly investigated. It causes a leaf -spot on 

 Rihes (mream from June to October. Tlie ])erithecia, MycosphiereUa 

 mirea sp. n., appear on the old leaves in spring and early summer. The 

 latter species has not been proved to pass to any other Rihes. 



Smut Diseases of Wheat.f — W. B. Mercer describes the different 

 diseases which have passed under the general term " smut." Stinking 

 smut, TiUetia Tritici, attacks all the grains in a head of wheat, and 

 these at the time of maturity consist solely of black spores. They 

 germinate readily and infect the plants in the seedling stage, the ger- 

 minating tube boring its way into the young shoot and advancing 

 towards the growing point of the stem and the flower-bearing portions. 

 The disease is spread by the dispersal of the ripe spores to other 

 grains during the threshing or during storage. 



Loose smut, Ustilago Tritici, also turns the grain into a mass of 

 black spores. Infection in this fungus takes place in the early stage 

 of flower-formation. Mercer describes the varioiis methods employed 

 for dealing Avifch these diseases. The seed-grains should be cleansed 

 from any adhering spores either by treatment with hot water or with 

 some fungicide. The former method has generally proved to be the 

 most serviceable and effectual. 



Research as to the Influence of External Factors on the Occur- 

 rence of Cereal Rusts. :j:~G. Gassner carried out a series of observa- 

 tions in Uruguay on this subject, testing and comparing plants living 

 as nearly as possible in the same conditions. He confirmed the 

 observations that old as well as young plants were subject to uredo- 

 spore infection, but in the former case only up to the time when 

 teleutospore growth began. He contrasts the duration-time of infection 

 in a number of species attacked liy Fwcinia yraminis, P. triticina, and 

 R. coroni/era. 



* Phytopathology, vi. (1916) pp. 419-27 (2 figs.), 

 t Joiirn. Board. Agric, xxiii. (1916) pp. U33-43 (2 figs.). 



t Centralbl. Bakt., 2te Abt. xliv. (1915) pp. 512-617. See also Bot. Centralbl., 

 cxxxi. (1916) pp. 654-7. 



