DISEASES OF PLANTS. 347 



thereof, relating to the invasion of grape leaves by P. viticola and its develop- 

 ment therein, and dealing with the incubation period, oil spots, conidiophores, 

 conidia and swarm spores, infection, stomatal relations, etc. 



Identity of the American and French mulberry blight, E. F. Smith 

 (Phytopathology, 4 (1914), No. 1, p. 34). — As the result of studies of leaves and 

 stems of mulberry from France and a comparison of the cultural characters of 

 Bacterium mori, the author was led to the conclusion that the same organism 

 is responsible for the disease in both America and France. 



Diseases and pests of cultivated plants in Samoa, K. Gehrmann (Arb. K. 

 Biol. Anst. Land u. Forstiv., 9 (1913), No. 1, pp. 1-12, figs. 11). — Discussing in 

 general the cultural conditions prevalent in Samoa, more particularly as related 

 to diseases of cacao, the author reviews briefly the historj', modes of attack, 

 etc., of cacao canker with an account of studies thereon by others. 



He concludes from his own investigations that Fusarium samoense n. sp. is 

 the cause of this disease, a Nectria and a Calonectria being found in connec- 

 tion apparently as saprophytes. The canker is said to be spread largely bj' 

 surface drainage of the soil. Admission of air and sunshine and employment of 

 radical pruning and fungicides are recommended. Some other diseases of cacao 

 with alleged causal organisms are briefly discussed. Among other injurious 

 agents noted are sulphurous volcanic gases, lightning, etc. 



A bibliogrnphy is appended. 



Cladosporium diseases of Ampelopsis tricuspidatum, M. T. Cook and G. W. 

 Wilson (Ahs. in Phytopathology, 4 (1914), No. 1, p. ^2). — A disease of this ivy 

 due to C. hcrharium is described. The organism is said to penetrate the stems, 

 causing a hypertrophy and resulting in the death of the vine. It is said that 

 the same fungus has been observed on grapes in California and in Europe. 

 During the past season it was reported common in New Jersey, where it caused 

 a great deal of injury. 



Stem rot and leaf spot of Clematis, W. O. Gloyeb {Ahs. in Phytopathology, 

 4 (1914), No. 1, p. 39). — ^A description is given of a stem rot and leaf spot of 

 Clematis due to Ascochyta sp. The fungus is said to live as a saprophyte on 

 the stem stub of the previous year and to produce numerous pj-cnidia. It works 

 slowly downward to the new shoots, which become girdled, the portions above 

 suddenly wilting. The same fungus has been observed causing a leaf spot of 

 C. paniculata. The disease has been produced artificially by inoculating with 

 pure cultures of Ascochyta, and by spraying with spores from pure cultures. 



Latent phases of disease following infection of Euphorbia cyparissias 

 with Uromyces, G. Tischlee (Bot. Jahrb. [Engler], 50 (1914), Sup., pp. 95- 

 110, figs. 7). — Previous work (E. S. R., 26, p. 650) has been followed up by a 

 further study of E. cyparissias infected with U. pisi. 



It is stated that by a treatment preventing the occurrence of the usual winter 

 resting period of the host it is possible to prevent the development of the fungus 

 on the young foliage and stems. The disease remains latent in such plants, 

 ready to break out on reestablishment of the regular resting period, as in the 

 ordinary life cycle of the host. In the latent condition of this fungus thus in- 

 duced the mycelium appears unable to make its way between the meristematic 

 cells of the growing point, although it may be present between the vacuolated 

 cells into which it sends tyi^ical haustoria. The observed variations in activity 

 of the parasite, it is thought, may be related to differences in osmotic pressure 

 in plant and parasite, as noted by MacDougal (E. S. R., 26, p. 433). It is stated 

 that even when the fungus is apparently absent from growing points of the 

 leaves of a given shoot, the parasite may appear in the floral organs later de- 

 veloped, causing a characteristic deformation thereof. 

 A bibliography is given. 



