Pflanzenkrankheiten. 201 



points claimed to be lacking for absolute proof. The work of Smith 

 and Boncquet now settled, they believe, this question in the 

 doubtless affirmative. By artificial confining of an insect upon one 

 plant and excluding it from another plant in the same pot, they 

 showed that the plant visited by the insect diseased after the usual 

 incubation period, while the other in the same pot did not. In 

 applying the insect for different lengths of time, it was found that 

 as Short a period as five minutes is sufficient to produce the disease. 

 In leaves, affected with curly top, an organism was found by 

 the authors, that agrees with Bacillus dianthi Bolley (1896), originally 

 described as the cause of the carnation disease afterward called 

 Stigmonose. This organism has been found abundantly as a sapro- 

 phyte in soil and on the surface of healthy beet leaves and is par- 

 ticularly abundant on the surface of beet seed. After surface sterili- 

 zation, however, it disappears completely except in the case of curh^ 

 top tissues. Beet leaves sickly, yellow or partially dead from other 

 causes do not show it at all under such conditions. Artificial inocu- 

 lations with this organism did not give any positive result; the 

 authors have not succeeded in producing the disease. By grafting 

 buds connected with wedge-shaped pieces of root tissue, from 

 diseased beets into the „Shoulders" of healthy ones, the authors 

 believe to have produced the typical disease in each of the few 

 instances thustar tried. M. J. Sirks (Haarlem). 



Stewart, V. B. and M. D. Leonard. The röle of sucking 

 insects in the disseminatio n of fire blight bacteria. 

 (Phytopathology. V. p. 117—123. 1915.) 



Since the experiments conducted by Waite who demonstrated 

 that bees are important in the spread of blossom blight, various 

 agents have been associated with the dissemination of the fire blight 

 organism, Bacillus amylovorus (Bur.) Trev. Forbes was probably 

 the first writer to attribute to the tarnished plantbug {Lygus pra- 

 tensis L.) the capability of spreading the fire blight disease and 

 Steward showed by experiments and observations that this plant- 

 bug is capable of carrying the causal organism to healthy shoots 

 where the bacteria gain entrance to the host tissue through the 

 feeding punctures made by the insect. Now the authors have made 

 such experiments with other sucking bucks: Adelphocovis rapidiis 

 Say, Campylomma verbasci Herrick-Schaeffer, Orthotylus flavosparsus 

 Sahlberg and Poeciloscytus basalis Reuter. From the results of the 

 experiments conducted it is apparent that all of the above named 

 species are capable of producing fire blight inoculations when the 

 causal organism is present. and are undoubtedly instrumental in 

 spreading the disease. Without question the tarnished plant-bug is 

 worthy of special consideration as a fire blight disseminator and also 

 the species Campylomma verbasci is undoubtedly of particular im- 

 portance. M. J. Sirks (Haarlem). 



Stone, R. E., The life history of Ascochyta on some legu- 

 minous plants. II. (Phytopathology. V. p. 4—10. 1915.) 



A small plot of Lathyrus sativus L. (grass pea) was found, infected 

 with an Ascochyta having somewhat the appearance of Ascochyta 

 pisi except that the pycnidia were smaller as were also the spores 

 which were frequently without a septum. It agrees closely with A. 

 lathyri Trail as far as spore measurements are concerned, but when 



