DISEASES OF PLANTS. 451 



blight of potatoes in tlie west of Irelaud, the author was struck with the 

 eomuiou occurrence of scabbiuess iu the potato tubers, and upon examination 

 lie found that the trouble was due to the fungus S. solani, which had been 

 hitherto considered as rare and apparently of only biological interest. In 

 investigating this trouble, the author found nearly every plat of potatoes iu 

 the district visited affected by the scab, the tubers being greatly reduced iu 

 market value, as well as being made almost worthless for seed purposes. 



This disease may be recognized with the aid of a low-power lens, showing 

 on the damaged skin of the tubers yellowish-brown particles resembling grains 

 of sand. These are spore-balls of the fungus, and in the first stage of the dis- 

 ease the tuber skin is raised above the general surface, the patches being ^ to i 

 hi. in diameter. Later the surface of the skin becomes ruptured and the spore- 

 balls liberated. The elevations then become depressions, and gradually tha 

 depressions become deeper and wider, the parasite literally gnawing away the 

 substance of the tuber. In some cases, however, the tuber successfully resists 

 the fungus by the formation of protective cork layers. 



A description is given of the fungus and its action in various media, after 

 which the author suggests means for its control. He regards the fungus as 

 a dangerous parasite, allied to the slime fungi Ceratiomyxa and Plasmodio- 

 phora. The potato crop becomes scabby, either through the planting of healthy 

 tubers in scabby soil or by planting scabby tubers. Want of drainage and 

 aeration of the soil tend to increase the virulence of attack. Crop rotation, 

 the treating of seed tubers with Bordeaux mixture or a 2 per cent solution 

 of copper sulphate before planting, the planting of uncut tubers, soil treatment 

 with sulphur, and thorough cultivation are reconmiended as remedial measures. 



A disease of sea-kale, E. S. Salmon {Gaid. Chron., 3. set',, 44 {190S), No. 

 ]123, pp. 1-3, figs. 3). — During the autumn of 190G sea-kale was observed to 

 be badly damaged by the fungus Rhizoctonia violucea. This fungus attacked 

 the roots, reducing the crop to a considei*able extent. So serious were the 

 effects of the disease that in 1907 experiments were carried on to determine the 

 possibility of preventing it by treatment of the seed beds. 



Just before planting in March, 1907, beds were prepared and treated with 

 solutions of copper sulphate, iron sulphate, corrosive sublimate, carbolic acid, 

 formalin, and petroleum, and dusted with sulphur and quicklime, which were 

 worked into the soil. The effect of the different treatments is shown. Copper 

 sulphate and corrosive sublimate reduced the disease to some extent, while the 

 plat receiving the carbolic acid at the rate of 1 oz. to 1 gal. of water was prac- 

 tically free from the disease. The other treatments were without definite effect. 



Some tomato fruit rots during 1907, Venus W. Pool (Nebraska Sta. Rpt. 

 1901, pp. 1-33, figs. 33). — Studies are reported on various diseases of the tomato, 

 among them the black rot due to Alternaria fasciculata, a Rhizoctonia disease, 

 the authracnose caused by Colletotriclimn lycopersici, a Fusarium disease due 

 to an undetermined species, and a disease due to Fusarinm solniii. 



The anthracnose was found on nearly all the late tomatoes, while the peculiar 

 blackened condition produced by Fusarinm sp. occurred on at least half of the 

 earlier fruits. The other rots occurred iu greater or less abundance during the 

 main part of the season. Plants which have an upright position of growth 

 with smooth, thick-skinned fruits, such as the Dwarf Champion, were found 

 freer from disease than the trailing thin-skinned varieties, as the Stone. 



The employment of proper sanitary measures and spraying with Bordeaux 

 mixtures are reconmiended for the conti'ol of these diseases. 



A bibliography is appended. 



A root rot of grapes due to Pestalozzia uvicola, F. A. Wolf (Nebraska 8ta. 

 Rpt. 19(7, pp. 69-72, fig. 1). — A report is given on studies made of ripe grapes 



