360 EXPEKIMENT STATION RECORD. 



and investigations are still in progress, the results of which are promised in a future 

 bulletin. 



Experiments on the bacterial diseases of potatoes, H. Jensen (C'enthl. Bakt. 

 w. Par., 2. Abu, 6 {1900), No. 20, pp. 641-64S). — Preliminary notes are given by the 

 author upon investigations of potato diseases which have been considered as of 

 probable bacterial origin. The first disease described is that sometimes known as 

 brown spot. In the tubers reddish brown spots are noticed. They are of different 

 sizes, irregularly distributed, and are bounded by cells of cork tissue. The protoplasm 

 of the cells is massed together, and the intercellular spaces filled with a brownish 

 substance. Thus far examinations have failed to show any connection between 

 the spots and external conditions, and neither bacteria nor fungi have l)een recog- 

 nized as the cause of the disease. All inoculation experiments have proved failures. 



The second disease described is the bacteriosis of the potato stem. In investi- 

 gating the so-called "black shank" of potato plants, the author found the diseased 

 portions filled with various organisms, but his preliminary investigations seemed to 

 indicate that a nucrococcus was the primary cause of the trouble. Inoculation 

 experiments showed that the disease could be readily produced and was easily 

 transmitted. The organism was found to secrete ammonia, and through the presence 

 of this substance it gains entrance to the host; otherwise the micrococcus appears to 

 be a saprophyte. 



Notes are given on the predisposition of potatoes t<j the disease, in which the 

 varying susceptibility of different varieties is shown. 



The author has investigated the statement of Wehmer (E. S. R., 10, p. 972) that 

 liacteria are of secondary importance in the wet rot of potatoes, with the result that 

 he differs from that author and affirms that bacteria are able to produce tiie disease. 



Experiments ■with fungicides upon potatoes in 1900, C. D. Woods {Maine 

 Sta. Bid. 73, pp. 49-57). — The author reports a series of experiments to demonstrate 

 the value of Bordeaux mixture when applied on a large scale, and also as a com- 

 parison between freshly prepared Bordeaux mixture and some of the ready-prepared 

 fungicides on the market. The plats were given 4 sprayings with a freshly prepared 

 Bordeaux mixture, consisting of 5 lbs. copper sulphate, 5 lbs. fresh lime, and 50 gal. 

 of water, and comparisons made with Boxal, Adler's Bordeaux, and Blanchard's 

 Lion brand Bordeaux mixture. In comparing the efficiency of the different mix- 

 tures, Adler's ready-made Bordeaux was found to be as efficient as that freshly pre- 

 pared, while the other two kinds were slightly less so. Where small quantities of 

 the fungicides are to be used the author believes that the ready-made or stock solu- 

 tions are to be preferred to those which are made by the user. 



The applications of the fungicides were made at a cost of about §2.50 per acre for 

 the 4 sprayings. When the potatoes were dug the crop was estimated, at the current 

 market rate, to be worth §106.40 per acre for the sprayed i)lats, as compared with 

 §62.60 for the unsprayed plats, giving a net return of about §40 per acre. 



How to fight potato enemies, C. D. Woods {Maine Sta. Bid. 73, pp. 58-64). — 

 The autlior popularly descrilje.s the principal fungus diseases and insect enemies to 

 which the potato crop is subject, and gives suggestions for tlie prevention of their 

 injuries. Formulas and directions for preparation are given for the more important 

 fungicides and insecticides, and the different forms of apparatus recommended are 

 described. 



Experiments with potato scab, H. Garman {Kentucky Sta. Bui. 91, pp. 56-59) . — 

 The author gives a record of experiments made in the season of 1900 for the preven- 

 tion of potato scab, comparisons being made between seed potatoes treated with corro- 

 sive sublimate and those soaked in various strengths of solution of formaldehyde. 

 The seed tubers used were badly scabbed, and while the disease did not do as much 

 harm as was expected from the condition of the seed potatoes a noticeable difference 

 in the prevalence and extent of disease was observed in favor of the potatoes from 



