DISEASES OF PLANTS. 53 



It is suggested that Long Island potato growers using liome-grown seed 

 should make a sprouting test of their seed potatoes. 



Morphology and cytology of the sexual organs of Phytophthora erythro- 

 septica, P. A. Muephy {Ann. Bot. [London], 28 (1014), No. 112, pp. 735, 736).-- 

 A preliminaiy account is given of morphological and cytological studies on P. 

 erytliroseptica, recently described as causing a disease of potatoes (E. S. R., 

 29, p. 550). 



The physiology of Phoma betae, W. Fischer (Jahresber. Kaiser Wilhclms 

 Inst. Landw. Bromhcrg, 1913, p. 28). — Experimentation showed that P. betce 

 can sustain a temperature of — 20° C. for 48 hours. Cultures subjected daily 

 during two or four weeks to temperatures ranging from to — 10° were not 

 killed by the cold. Tests with preparations in use as sprays showed that 

 while copper sulphate, formalin, and carbolic acid in the concentrations and 

 durations usually employed are ineffective as against P. hctce, corrosive sub- 

 limate and chiuosol quickly show strong fungicidal action against this fungus, 

 checking growth in concentrations as low as 1 : 10,000, but having no injurious 

 effects on the beet seed under treatment. 



Black spot of the tomato, G. P. Darnell-Smith {Agr. Oaz. N. 8. Wales, 25 

 (1914), No. 12, pp. 1069, 1070).— According to the author the black six)t of 

 tomato is widely spread in New South Wales, probably causing more loss than 

 any other tomato disease. 



A study of the trouble has led him to believe that both bacteria and fungi 

 are concerned in the black spot. The sequence of events in the production of 

 the spots would appear to be injury to the skin, entrance of bacteria, and in- 

 fection by Macrosporium. There is believed to be evidence that the fungus 

 alone is capable of producing tyiiical black spot. The disease is considered 

 largely dependent upon drought conditions, and where tomato plants are ade- 

 quately shaded and watered the trouble may be very much reduced. If it is 

 considered desirable, in addition to providing an adequate water supply, the 

 plants may be sprayed with Bordeaux mixture or lime-sulphur solution, the 

 application of the fungicide assisting in checking the tomato leaf spot due to 

 Septoria lycopersici. 



Black hearted turnips, C. D. Woods (Maine Sta. Bui. 236 (1915), pp. 57-59).— 

 The attention of the station was called to a serious trouble of turnips, in 

 which the roots were perfect on the outside, skins bright and smooth, but 

 when cut the flesh had large patches of a dull-bix)wn color, the discoloration 

 extending nearly to the skin. An examination of diseased material showed 

 that the black heart was not produced by fungi or bacteria, but was apparently 

 a condition arising from some factor or factors in the growth of the plant. A 

 demonstration experiment was carried on to determine the relation of ferti- 

 lizers and varieties to this disease. 



The results obtained are not considered definite, but they indicate that there 

 Is a difference in varieties in regard to their susceptibility to the disease and 

 that the plants to which stable manure was added had less of the trouble than 

 the others. 



Fire blight of pear and apple, H." L. PtEES (Washington Sta., West. Wash. 

 Sta. Mo. Bui, 1 (1913), No. 4, pp. 6-9, figs. 7).— A popular description is given 

 of the bacterial blight of pears and apples, with suggestions for its control. 



Blight resistance in pears and pear stocks, F. C. Reimeb (Mo. Bill. Com. 

 Eon. Cal., 4 (1915), No. 3, pp. I45-I49, fig. i ) .—Attention is caUed to the 

 resistance of certain species and varieties of pear-tree stock to pear blight. 



Among the species reported upon it is said that Japanese pear stock (Pyrus 

 sinensis) and stock of a species from China (P. betulwfolia) have been success- 



