148 Pflanzenkrankheiten. 



Ernte; der Schaden betrifft nur die Staubbeutel, indem die Keim- 

 fähigkeit des Pollens in Folge der Deformation des Pollens verlustig 

 geht. Die Keimfähigkeit der von kranken Pflanzen gesammelten 

 Samen beträgt 63 %, die der gesunden 43 "^/V,. Die kranken Pflanzen 

 bringen weniger Samen hervor als die gesunden; erstere sind klein 

 und geschrumpft, daher auch das absolute Gewicht ein etwas klei- 

 neres. Man muss in Samenprüfungsanstalten auf den neuen Pilz 

 achten. Im Jahre 1913 war der Pilz in Russland weit verbreitet; 

 eine schlechte Kleesamenernte ist hier oft auf den Pilz zurückzu- 

 führen. Die kranken Blüten kann man oft schon aus der Ferne 

 bemerken, da sie eine blass violette Schattierung besitzen. Doch 

 entscheidet da nur die Untersuchung der Staubbeutel: normale sind 

 gelb, die kranken infolge des Sporenpulvers grau gefärbt. 



Matouschek (Wien). 



Borcea, I., Nouvelle liste des Zoocecidies de Roumanie. 

 (ßull. Sect. scient. Acad. roum. III. p. 238—241. 1915.) 



Comme continuation de sa publication anterieure „Zoocecidii 

 din Romania" et de celle de Brandza (voyez Bot. Cbl. Bd. 126. 

 p. 593) l'auteur tient ä completer dans la presente communication 

 les listes des precedents memoires par quelques nouvelles formes 

 'Observees, ayant interet ä ce que quelques-unes appartiennent ä un 

 nouveau groupe cecidogene: les Nematodes, d'autres enfin etant du 

 type mediterraneen ou du type des steppes. 



M. J. Sirks (Haarlem), 



Drayton, F. L., The Rhisoctonia lesions on potato stems. 

 (Phytopathology. V. p. 59—62, 1915.) 



Investigators of the Rhisoctonia disease of potatoes, caused \iY 

 the fungus now referred to as Coryneiim vagmn var. solani Burt, 

 have referred to the dark brown lesions occurring on the Under- 

 ground main stems and on the tuber-bearing stolons as the most 

 prominent and typical Symptoms of the disease. These lesions are 

 irregulär in shape, varying in size from the head of a pin to an 

 area of some few centimeters in extent, sunken, dark brown and 

 usually running longitudinally on the stem, but sometimes comple- 

 tely girdling the thinner portions, This injury is so constantly 

 associated with other evidences of Rhisoctonia that it was taken for 

 granted to be due to the parasitic growth of the Rhisoctonia myce- 

 lium; but apart frora the fact of its association and the presence of 

 superficial hyphae, the author failed to discover any further proof 

 in Q-nj of the literature at his disposal. 



In this paper he communicates the results of his microscopical 

 investigations about these lesions, destined to determine definitely 

 whether, and if so to what extent they vvere reall}?^ produced by 

 the mycelium of the Rhisoctonia. Indeed, cells of the cortex, vascular 

 bundles, and pith all were found to be invaded by mycelium, which 

 from transverse and longitudinal sections proved to be that of 

 Rhisoctonia. The mycelial masses in the cortical cells resemble clo- 

 sely the structure of the so-called Rhisoctonia-scleroüa. and they no 

 doubt give the brown color to the lesions and may well be a means 

 of infecting subsequent crops in the same field if left on or in the 

 ground in the same way that the sclerotia formed on the roots are 

 a means of reinfecting subsequent crops. This would emphasize the 



