544 EXPEKIMENT STATION EECOED. 



differentiate them, tliey do not produce the same effect whien grown on culture 

 media, Tliey think the name Citromyces an inappropriate one, as other organ- 

 isms tliat can not be referred to ^his genus produce citric acid from glucose, etc. 



On root tumors, A. Stift {Osterr. TJngar. Ztschr. Zuckerindus. u. Landto., 

 Jfl (1912), Xo. 2, pp. 241-2Jf9, figs. 6). — A discussion is given of a beet root de- 

 formation, claimed to be different as to character and cause from the tumorous 

 growths usually described. The shape of growth, which in this case involves the 

 main root and differences of composition are held to support this claim. 



The causes of beet blight, L. Peters {Arb. K. Biol. Anst. Land u. Forstiv., 

 8 (1911), No. 2, pp. 211-259, figs. 12; aU. in Ztschr. Pflanzenhrank., 22 (1912), 

 No. 3, pp. 179, 180). — The author holds that this disease is caused by Pythiuni 

 debanjanum, Plioma betee, and Aphanomyces Icevls. The last named has not 

 before been pointed out as a probable factor in this disease. 



Investigations of the potato fungus Phytophthora infestans, L. R. Jones, 

 N. J. GiDDiNGS, and B. F. Lutman (U. S. Dept. Agr., Bur. Plant Indus. Bui. 2^/5, 

 pp. 100, pis. 10, figs. 10). — This paper embodies the main facts in the develop- 

 ment of the disease and of methods for its control by spraying and other stand- 

 ard practices, and also contributes a number of new facts as to the development 

 of resting spores by the fungus. The work was begun and carried on to a con- 

 siderable extent at the Vermont Station in cooperation with the Bureau of 

 Plant Industry. 



The potato disease termed the late blight and rot due to P. infestans is one 

 of the most serious of all potato diseases in Europe and America. It is common 

 in the northeastern States, being favored by rather cool, moist summers, but 

 farther south and west it is less common and probably only occurs when intro- 

 duced with seed from the North. It does not persist where late summers are 

 warm and dry. 



The disease does not attack the leaves, as a rule, until after the blossoming 

 period. The fungus develops first on the foliage, from which it passes by means 

 of siK)res that are washed into the soil to the tubers, in which it hibernates. 



Studies of infection, transmission, and disease control have shown that tuber 

 infection in the field may be prevented by spraying the soil even when the fungus 

 is allowed to develop unchecked on the foliage. Tubers may be infected from 

 contact with blighting foliage at digging time. Secondary infection of tubers 

 may occur in the soil or in the storage bin. 



When the tops are attacked by late blight the harvesting of the tubers should 

 be delayed for some time after the death of the tops. Dry, cool storage is of 

 primary importance to prevent the spread of the disease in bins, and the use 

 of lime or formalin disinfection has proved valueless. Wind and water are 

 considered the most important agencies in local spore distribution, although 

 leaf-eating insects may carry the spores to some extent. 



The method described by Jensen of covering the tubers to a depth of 4 to 5 in. 

 was found valuable in preventing infection through the soil, and disinfecting 

 tubers designed for seed purposes by exposure to dry heat, 40° C. for 4 hours, 

 was also demonstrated to be of value in preventing the infection of the disease. 

 The results of 20 years' s]iraying exiierimeuts at the Vermont Station have 

 shown that spraying the foliage with Bordeaux mixture is an almost com- 

 plete remedy against both the blight and the rot, and also operates beneficially 

 to the potato plant in other ways (E. S. R., 26, p. 53). 



The fungus causing this disease has been carried in pure culture since 1904 

 and a considerable niunber of facts determinetl relating to its life history. 

 Strains have been grown continuously for more than 5 years without any evi- 

 dence of change in pathogenicity or other characters. The limits of alkalinity, 

 acidity, temperature, etc., for growth and sitore formation have been deter- 



