154 EXPERIMENT STATION RECORD. [Vol.43 



scab. Sulphur and amnionium sulphate tend to decrease the amount of s<.'alj 

 and lime and manure to increase it. The skin structure of the tuber seems to 

 be but slightly affected by the application of fertilizers, at least on sandy soil. 

 It is believed that any changes the fertilizers may bring about in the preva- 

 lence of scab are due to their effect on the numbers or pathogenicity of the 

 organisms rather than on the tuber itself. 



Potato leaf roll, F. W. Neger (Deut. Landw. Pretise, Jf5 (1918), No. 76, pp. 

 JfGD, .'i70, figs. Jf). — The author makes a first report of data obtained in studies 

 regarding tlie etiology of potato leaf roll. These data are sai^ to have shown u 

 very close relation between this condition and the presence of starch in the 

 superficial cells of the leaf. 



Tip burn of the potato and other plants, B. F. Lutman (Vermont Sta. Bui. 

 214 (lyiO), pp. 3-28, pis. 2, figs, 9). — According to the author, tip burn is one 

 of the most important limiting factors in potato production, being exceeded 

 only by the Colorado beetle and late blight. Tip burn of the potato is said 

 to be due to excessive heat and sunshine during late July and early August, 

 the advance of the tip burn occurring only on hot brilliant days, while during 

 cloudy cool weather it makes no progress. An inordinate transpiration from 

 portions of the leaflets directly affected results in a wilting from which the 

 parts seriously injured do not recover. High osmotic pressure of the sap of the 

 stalks of the plants as compared to that from the leaves undoubtedly aggravates 

 the disease. The author found that tip burn can be simulated in the green- 

 house even in early spring by directing an excess of sunlight on any portion 

 of the potato foliage. Tip burn may be largely prevented by shading and to 

 some extent by application of Bordeaux mixture. Early varieties in general are 

 affected sooner and more seriously than late ones. The foliage of the latter 

 often survives the attack and renews growth in September. 



The spindling sprout disease of potato tubers, C. O. Appleman {Maryland 

 Sta. Rpt. 1919, p. XLV). — Considerable progress is said to have been made in 

 locating the physiological disturbance. Several successful attempts were made 

 in producing the disease by artificial means. 



Tomato diseases, C. C. Brittlebank (Jour. Dept. Agr. Victoria, 11 (1919), 

 Nos. 4, PP- 231-235; 8, pp. 498-500). — A descriptive account is given of tomato 

 di.seases found in Victoria, including leaf mold {Alternaria solani), leaf spot, 

 blight or rust (Septoria lycopersici), wilt (Fusarium solani), Sclerotium 

 disease (Sclerotinia sp.), root rot {Rhizoctoniu solani), Irish potato blight 

 (Phytophthora infestans), and brown rot or wilt {Bacillus solan<icearuin) . 



To these the author now adds a new tomato disease, proposing the name 

 " spotted wilt." This disease has appeared within the last three years on 

 tomato plants, its origin and mode of introduction being unknown. No causal 

 organism has yet been isolated, and no control method has been devised. The 

 period of greatest virulence of this disease coincides with the prevalence of 

 swarms of canary flies or jassids, the plants recovering to a considerable ex- 

 tent afterwards, though some plants still show the presence of the disease. 

 This is said to be the most serious disease that the local grower has had to meet. 

 During the present season, fully 50 per cent of suburban garden plants have 

 been destroyed. In the country districts the disease has made considerable 

 progress, and diseased plants have been found in nearly all parts of Victoria. 

 Symptoms of the disease are described. The author suspects that this disease 

 may be identical with one which has been under investigation, in the United States 

 by Selby (E. S. R., 8, p. 991) , and later by Howitt and Stone (E. S. R., 36, p. 350). 



Apparently fumigation does not cause the disease, which is thought to be 

 physiological Iti character, possibly in some way connected with some chemical 

 or i>hysical deficiency in the soil, which is apparently overcome by sterilization. 



