726 



SCIENCE 



[N. S. Vol. XXXII. No. 



plosion or series of explosions that wrecked 

 the geyser field. 



That here the result of geyser action has 

 heen powdered sand grains rather than geyser- 

 ite, as at the Yellowstone, would be due to the 

 different kinds of rock at the two places. 



Underlying Yellowstone Park are compact, 

 igneous rocks. They would be gradually dis- 

 solved by hot alkaline water with formation 

 of geyserite. 



At Coon Butte the underlying rocks are 

 loosely coherent sandstones whose grains 

 would be carried up bodily, and solvent action 

 would be relatively less. 



Other things being equal, the time required 

 to carry up the sand grains and fragments at 

 Coon Butte would be much less than that re- 

 quired to dissolve an equal amount of rock at 

 the Yellowstone Park and to deposit it in the 

 form of geyserite. 



John M. Davison 



PiTTSrOED, N. Y., 

 August 23, 1910 



BLACK LEG OR PHOMA WILT OF C.4BBAGE : A NEW 



TROUBLE TO THE UNITED STATES CAUSED 



BY PHOMA OLEEACEA SACC. 



Within the past few years there has ap- 

 peared in the cabbage districts of Clyde and 

 Fremont, Sandusky Co., Ohio, a cabbage and 

 cauliflower disease apparently new in the 

 United States. The disease has been under 

 the observation of the writer since June of 

 the present season. Pield symptoms together 

 with the determination of the causal fungus 

 show the disease to be identical with that 

 known in Holland as " Fallsucht " (drop dis- 

 ease or falling sickness). J. Eitzema Bos, in 

 Zeitschrift fur Pfianzenkraiikheiten, Band 16, 

 pp. 257-276, 1906, has fully described this dis- 

 ease and states the trouble is due to the 

 fungus Phoma oleracea Sacc. He further 

 describes a storage disease of cabbage knovm 

 as " Krebsstrunke " (stem cancer) brought 

 about by the same organism. 



What appear to be similar diseases to the 

 above have been noted by Prillieux' to occur 



'■ " Maladies des Plantes Agricoles," Vol. II., 

 p. 295, 1897. 



in the forage cabbage districts of the prov- 

 ince of Vendee, in western Prance, and by D. 

 McAlpine' in the cabbage and cauliflower 

 districts of South Australia. Both of these 

 writers assign Phoma Brassicce Thiim. as the 

 causal agent. 



The diseases as described by Prillieux and 

 McAlpine are quite similar to that described 

 in Holland and to that found in Ohio. The 

 former calls the trouble " Pourriture des 

 pieds de Chou," that is, " foot rot of cab- 

 bage," and the latter designates the disease 

 " black leg or foot rot of cabbage and cauli- 

 flower." 



According to Bos (see citation above) and 

 Quanjer'' there is reason to believe that the 

 organism assigned by Prillieux as the cause 

 of the disease, is identical with Phoma 

 oleracea Sacc. 



The disease is quite important in each of 

 the countries noted. In South Australia, ac- 

 cording to McAlpine, it " is perhaps the most 

 serious trouble with which the grower has to 

 contend." He does not mention the presence 

 of black rot or the Fusarium wilt. 



Symptoms. — The work of the disease is 

 early to be observed in the infected seed beds, 

 being often conspicuous one or two weeks 

 prior to transplanting. The preliminary 

 symptom is that of white, slightly sunken, 

 elongated oval areas on the stem usually be- 

 low the point of leaf attachment. Occasion- 

 ally the disease spots occur on the leaves. 

 There appear early in these lesions small, 

 black pycnidia equally, though somewhat 

 sparingly, distributed over the affected areas. 

 Each pycnidium contains myriads of spores 

 which are evidently the source of a rapid dis- 

 semination of the disease at the time of trans- 

 planting. 



In the early stages of the disease the fungus 

 may be plated out in pure culture as the sole 

 occupant of the lesion. Later the lesion 

 breaks and bacterial decay sets in. In the 



' " Fungus Diseases of Cabbage and Cauliflower 

 in Victoria, and their Treatment," Dept. of Agr., 

 Victoria, January, 1901. 



' Zeitschrift fiir Pflanzenkrankheiten, Band 17, 

 1907, pp. 259-267. 



