DISEASES OF PLANTS. 973 



The results of those experiments are presented in tabular form. It was found that 

 there was a marked difference in the resisting power of different varieties to blight. 

 As a rule early varieties were first attacked. The yield from early varieties was 

 about tlie same whether dug in September or October, while the yield of late varie- 

 ties was greatest when dug at the latter date. The yield was sutRciently increased 

 to more than repay the cost of spraying. Bug Death at the rate of 25 pounds per 

 acre for each application was sufficient to destroy the potato beetles, but no larger 

 yields were ol)tained when this material was used than when the potatoes were 

 sprayed with Paris green. It was found that j>repared lim(> was more convenient to 

 use than lump lime. The cost per pound was greater, but its use caused a saving in 

 time. 



Studies in potato rosette, II, A. D. Sei.hv {Ohio Sta. Bui. 14,5, pp. 15-2S,figs. 

 4)- — In continuation of a leport on potato rosette (E. S. R., 15, p. 268), an account 

 is given of experiments conducted in 1903 for the prevention of this disease. Rosette 

 seems to be almost universal in its occurrence on early potatoes, causing from 5 to 25 

 per cent of the plants to be diseased. The preliminary experiments with formalin 

 for the prevention of this disease were so promising that they were continued and 

 comparisons made with formalin, sodium sulphid, lime, potassium suli)hid, and 

 corrosive sul)limate. Three varieties of potatoes were used in the experiments, the 

 conditions of the different lots being made the same as nearly as possible. 



Summing up the results, the author says that they are somewhat variable where 

 the tul)ers were planted on badly infected soil, but strongly marked and decisive 

 where planted on uncontaminated soil. The results obtained do not show any great 

 difference between the efficiency of sodium sulphid and formalin as a means of treat- 

 ing the seed tubers, yet the simplicity of the formalin treatment is decidedly in its 

 favor. 



Investigations in rotation have sliown that a three-crop rotation of potatoes is not 

 sufficient for the elimination of this disease. The author recommends for the pre- 

 vention of potato rosette that all seed potatoes be treated l)efore planting ])y immers- 

 ing them for 2 hours in a solution of formaliji containing 1 lb. of formalin in 80 gal. 

 of water. 



A brief description is given of tomato rosette and a rosette disease of lettuce, both 

 of whicli are to be the subject of future investigation. 



Leaf spot of tobacco, C. J. Koning {Bladvlekken op Tubal-. ylm.'<ter<him: J. If. de. 

 JiusKeij, 1903, pp. S, ]>l. 1). — The appearance of this disease is briefly desc^ribed and 

 notes given on its distribution. The author observed that infection frecjuently took 

 place through injuries in the leaves caused by the rubbing of leaves together during 

 win<l storms. 



The bitter rot of apples, W. B. Aiavood ( Virginia Sta. Biil. 14^, pp. 249-279, 

 fig.'i. 1')). — A discussion is given regarding the scientific and common name for the 

 fungus which causes this disease. The author adopts the name Ghmorclla rafoma- 

 cidans. The fungus is most injurious to fruit, both grape and apple, when nearly at 

 maturity, but it is often observed at much earlier stages. In badly infested orchards 

 composed of unusually suscepti))Ie varieties of apple trees, the disease can not be 

 readily controlled. Detailed notes are given on tlie appearance of the disease, the 

 microscopic cliaracter of the fungus, germination of the spores, and character of the 

 mycelium. 



In studying the sources of infection evidence was obtained that mummied fruits 

 are largely responsible for spreading the disease. No evidence was obtained to show 

 that cankers on the branches were connected with this disease. Bitter rot was 

 found on trees where no cankered lindjs could be discovered, and vice versa. Among 

 the most susceptible varieties are the Alljemarle Pippin, York Imperial, Ben Davis, 

 and Wine.«ap. In controlling this disease it is reconnnended that mummied fruits 

 be removed and destroyed and the trees sprayed with Pxtrdeaux mixture after July 1, 

 Winter treatments appear to have no beneficial results. 



