646 EXPERIMENT STATION RECORD. 



made both in the greenhouse and in the open air to determine the germinative 

 ability of old solerotia of the common ergot (Clarirrpfi puipurca) . 



It was found that sclerotia more than '2 years old had lost all power of 

 germination. Those remaining dormant the first year germinated readily the 

 second year and at about the same time as fresh sclerotia. Mold.v and broken 

 sclerotia often retain a high percentage of their viability. Contrary to the 

 popular belief that ergot must be kept moist over winter or it will not germinate, 

 the author found that neither sowing in dry soil nor keeping the sclerotia in 

 glass jars until time for experimental sowing diminished their gemuinative 

 ability. 



The time at which the development of promycelium and conidia takes place 

 :s approximately the same every year and corresponds with the normal flower- 

 ing period of the cereals on which the fungus is a parasite. 



Potato diseases, E. Lange {Die Eartoffelkmnlheiten. Leipslc: O. Schnei- 

 der, J!)05. PI), l.i. figs. 3, charts 3). — This is a brief descriptive guide to. accom- 

 pany the colored charts which illustrate various diseases of potatoes, among 

 them the potato rot, black shank or stem rot, leaf curl, scab, wet and dry rot of 

 tubers, bacterial rot. nematodes, etc. 



A contribution to the knowledge of potato scab, 11. T. Gtissow (Ztschr. 

 PflatizcnJcrank., 16 {Hiod). .Yo. 3. pp. 13.1-137, pJ. 1). — A discussion is given of 

 the form of potato scab that has been variously referred to as Rhizoctonia 

 violacea and R. solani (E. S. R., 14, p. 159; 1(1. p. 788: 18. p. 1.51). The author 

 claims that these 2 species of Rhizoctonia are identical, and from his own 

 observations and those of Rolfs (E. S. R.. l(i, p. 788). he is convinced that the 

 lierfect form of the fungus is CorficiiiDi nn/inii .sohiiil. 



A bacterial rot of the potato caused by Bacillus solanisaprus, F. C. Har- 

 rison (Centbl. Bald, [elc], 2. AM., 11 (1906), Nos. 1-2, pp. 3Jf-39 ; S-J,, pp. 

 120-128; 5-7, pp. 166-17.',; 11-13, pp. 38J,-398, pis. S).— The bacterial rot of 

 potatoes has been more or less prevalent in the province of Ontario during the 

 past 5 or G years and was particularly troublesome in 1904 and 190.5. This 

 disease resembles somewhat that described as being rather widespread in 

 Germany and which is also known in England under the name of black shank 

 disease (E. S. R., 15, p. 374). 



Usually the first symptoms of the disease appear when the plants are in full 

 vigor of growth, when a plant here and there in the field presents a sickly 

 appearance, with drooping leaves somewhat discolored or yellowed. In a few 

 days the stems lose their erect appearance and gradually fall to the ground, 

 the whole stem and leaves finally shriveling up. When the leaves are turning 

 yellow, black areas nuiy be seen on the stems and ])etioles; and if these are cut 

 through, the vibrovascidar bundles and adjacent tissues will be found black or 

 brown, depending on the progress of the disease. The stems are usually most 

 discolored or blackened near the ground, but sometimes the discoloration is 

 higher up the stem. 



The tubers show the most characteristic indications of the disease, and when 

 the plant appears to be in a fairly healthy condition the tubers may be badly 

 diseased. I'otatoes which appear sound if carefully examined will show dis- 

 colored areas somewhat like a bruise, and as the disease progresses the flesh 

 beneath the darkened portion becomes soft. On breaking the skin a white 

 turbid liquid can be pressed out, which rapidly turns blacTt on exposure to the 

 air. In later stages of the disease the flesh softens to a watery pulp and 

 becomes highly oflrensive, with a putrefactive odor. If potatoes are dug and 

 stored in cellars or pits the disease continues to spread. 



The author has found constantly associated with this disease an organism 

 to which the n:une Bacillus solanisaprus is given. This has been isolated, 



