DISEASES OP PLANTS. 743 



Continuing previous work (E. S. 11., 32, p. 3-12), Bordeaux mixture is found 

 to be protective and to increase the yield of tubers if sprayed on when the 

 plants are 6 in. high and two or more times thereafter at intervals of from 10 to 

 14 days. This, however, delays the ripening of the tubers. 



Protective measures available include careful selection and handling of seed 

 potatoes, burning of haulms, rotation of crops, and isolation from solanaceous 

 crops which are susceptible to Phytoiihthora infestans. If the tops are attacked, 

 fallen spores may be killed by spraying the ground. 



Notes on tlie distribution and prevalence of three important sweet potato 

 diseases, L. L. Harter (Phytopathology, 5 {1915), No. 2, pp. 124-126) .—Accord- 

 ing to the author the stem rot of sweet potatoes, due to Fusarmm hyperoxy- 

 sporum and F. batatatis, is known to occur in New Jersey, Delaware, Mary- 

 land, Virginia, Alabama, Ohio, Illinois, Missouri, Iowa, Kansas, Oklahoma, 

 Arkansas, North Carolina, Georgia, and Mississippi. The black rot, caused by 

 Sphceronema flmbriatum, is reported as occurring in New Jersey, Delaware, 

 Maryland, Virginia, Ohio, Illinois, Missouri, Iowa, Kansas, Oklahoma, Texas, 

 Arkansas, North Carolina, Georgia, and Alabama. The foot rot, a compara- 

 tively new disease due to Plenodoinus destruens, is reported from Virginia, Mis- 

 souri, Iowa, and Ohio. 



New lig-ht on curly top of the sugar beet, R. E. Smith and A. Boncqtjet 

 {Phytopathology, 5 {1915), No. 2, pp. 103-107, figs. ^).— The authors record 

 certain facts which recently came to liglit in the study of the cuily top of the 

 sugar beet. They have confirmed the investigations of Ball (E. S. R., 20, 

 p. 954) and Shaw (E. S. R., 23, p. 557) regarding the relationship between the 

 leaf hopper, Eutettix tenella, and the occurrence of the disease. A study of 

 affected plants has shown definite lesions accompanied by an organism which 

 agrees fairly well with Bacillus dianthi, previously described as the cause of 

 the carnation disease (E, S. R., 8, p. 235). 



The authors have not succeeded in producing the disease by inoculating plants 

 with this organism, and it is not known whether or not it is the inciting factor 

 causing and inhabiting the lesions. Further study on this disease is said to be 

 necessary. 



Sugar beet mosaic, C. O. Townsend {Science, n. ser., ^2 {1915), No. 1076, pp. 

 219, 220). — The author states that while this disease has been observed for a 

 number of years, it has not hitherto been described. It is known to occur in 

 the middle and western portions of the United States and appears to be increas- 

 ing from year to year. In some commercial fields it is said to affect from 10 

 to 20 per cent of the stand and threatens to become a limiting factor in sugar 

 beet culture in some areas. 



The leaves of the affected plants are said to be mottled yellow and green. 

 The spots are not always sharply defined, but usually shade into each other, 

 giving the affected leaves a yellowish appearance. Only a part of the leaves 

 on a beet are diseased, at least during the early stages of development. Affected 

 leaves, if numerous, generally occupy only one side of the beet crown, normal 

 leaves occupying the opposite side, giving the beet top a one-sided appearance. 

 The shortened petioles give the leaves a dwarfed appearance, as in the case 

 of curly top. The roots are said to be dwarfed and often hairy, further 

 resembling curly top. While the two diseases are somewhat similar, they are 

 easily distinguished from one another. 



Tobacco root rot observations, W. A. Barnet {Canada Expt. Farms Rpts. 

 1914, pp. 1022, 1023). — In connection with investigations of tobacco growing, the 

 author reports plats of Burley tobacco in which certain rows or portions of the 

 field seemed to have their growth completely arrested. This dwarfed appear- 

 ance of the plants was prevalent in the field, and, it is said, was produced by 



