DISEASES OF PLANTS. 447 



So far as the writer knows, this disease, wliich seems quite distiuct from 

 l)lack rot or heart rot, has never been descrilied. 



The disease appeared in soils in whieli celery had l>eeu grown for many suc- 

 cessive years, and a species of Khizoctouia was found on many of the roots. 

 A careful study of the fungus led the author to believe that it was not wholly 

 responsible for the trouble, at least not in the beginning, nor could any bacteria 

 or other organisms be found constantly associated with it. The diseased spots 

 in the fields always seemed to be where the ground was slightly lower or not 

 well drained, and it seems clear that soil conditions were responsible for a con- 

 siderable portion of the trouble. It is believed that poorly drained soils are 

 the primary cause of this root rot and that the Rhizoctouia is associated with it 

 only in the later stages of decay. 



Potato spraying experiinenj;s in 1906, F. C. Stewart et al. {New York 

 State Sta. Bnl. 290, pp. 239-321, pis. 2).— This is a report of the fifth year of the 

 1 0-year series of potato spraying experiments begun in 1902. The experiments 

 were carried out on the same lines as previously indicated (E. S. R., IS, p. .52), 

 SO separate experiments being reported in this bulletin. 



At Geneva, a sjirayings increased the yield 0;> bu. per acre, while 3 sprayings 

 increased it 31.ir> bu. The gain is said to l)e due chiefly to the prevention of 

 tlie late blight. At Riverhead the gain due to 5 sprayings was .5.3.25 bu. per 

 acre and to 3 sprayings 21.5 bu. Here the chief enemies were the flea-beetle 

 and the late blight. No rot was observed at either station. 



In the farmers' business experiments, in 15 experiments, including 225.6 acres 

 sprayed 5 or G times, the average gain due to spraying was 42.6 bu. per acre. 

 The total cost of spraying was $5.18 and the average net proflt .$13.89 per acre. 



In the volunteer experiments, 62 experimenters sprayed 598 acres and report 

 gains averaging 44.5 bu. per acre, the largest being 132.6 bu., while 2 repoi't no 

 gain whatever. 



Five years of potato spraying, F. H. Hall et al. {New York State Sta. 

 Bui. 290, popular ed., pp. 12). — A popular edition of the above. 



The nature and control of blackleg of potatoes, Kleberger {Ztschr. 

 Pflanzcnkrank., 11 {1907), No. 2, pp. S0-8J).— The blackleg of potatoes is said 

 to spread from the seed tubers to the stems and young tubers, causing their 

 destruction. The direct infection of the stems seems to be also probable. A 

 large amount of hunms in the soil or heavy applications of stable manure favor 

 the development of the disease, and early and medium varieties of potatoes are 

 more subject to it than those maturing late in the season. The disease in the 

 field may spread from plant to plant, the rapidity of the spread depending on 

 the distance separating the plants as well as the amount of humus in the soil. 



Soaking seed potatoes in fungicides before planting was tested, and as a 

 result a 2 per cent Bordeaux mixture solution is recommended as more efficient 

 than corrosive sublimate in controlling the disease. 



A disease of peas and beans, P. Masseron (Semaine Agr. [Paris}, 26 {1907), 

 No. 1370, p. 270; noted in Frog. Agr. et Vit. {Ed. VEst), 28 {1907), No. 35, p. 

 267). — An account is given of a sclerotium disease of peas and beans, which is 

 due to the fungus Sclerotinia libertiana. 



This disease was especially destructive in certain regions in France during the 

 spring of 1907. Its unusual development is said to be due to the intensive 

 culture of peas, that crop being fre(|uently grown successively upon the same 

 soil, and also to favorable conditions of humidity and temperature. The fungus 

 is said to attaclc peas, beans, Jerusalem artichokes, ruta-bagas, carrots, beets, 

 maize, and hemp. 



In order to prevent its destructive occurrence, it is reconnnended that rota- 

 tions should be followed so that for a period of at least 4 years susceptible 



