93 



Arsenical Poisoning of Potato Leaves. 



In many sections where Paris green in water is applied to potatoes 

 injuries are produced which can not be distinguished from early blight 

 by any ordinary examination. It frequently happens, therefore, that 

 farmers are led to believe that their potatoes are affected with early 

 blight and other diseases when the trouble has been brought on by 

 themselves through the improper use of Paris green. Injuries result- 

 ing from the use of this substance are very apt to occur where flea 

 beetles have eaten the foliage. The arsenic attacks the tissues at such 

 points, and as a result more or less circular brown spots are produced, 

 having for their centres the holes eaten out by the flea beetles. By 

 combining the Paris green with Bordeaux mixture, as already described, 

 these injuries may be wholly avoided. 



Concluding Remarks. 



The cost of the work of spraying as described here will depend to 

 a conderable extent upon the kind of machinery used and the price 

 paid for labour. With suitable apparatus and labour at $1 50 per day, 

 potatoes may be sprayed six times for about $6 per acre. This esti- 

 mate is based upon experiments extending over several years and 

 includes the cost of chemicals as well as labour. The cost of treating 

 scab is mainly in the labour involved in dipping and drying the seed 

 and seldom exceeds 15 cents per acre. Much attention has been given 

 to the effects of Bordeaux mixture on the growth and yield of potatoes 

 aside from its value in keeping parasitic foes in check. It has been 

 shown conclusively that it pays to apply this preparation if for no 

 other purpose than to induce a more vigorous growth. Three or four 

 applications of the mixture have in many cases increased the yield of 

 potatoes 50 per cent, so that no matt r where the crop is grown or 

 whether diseases are present or not the writer feels warranted in re- 

 commending the application of the mixture on the ground that its use 

 will yield a handsome return. 



ADDITIONS AND CONTRIBUTIONS TO THE 

 DEPARTMENT. 



Library (Serials.) 

 Europe. 



British Isles. 



Board of Agri, Leaflet, No. 67 [Secretary.] 



Botanical Magazine. April. [Purchased,] 



Bulletin, Kew Gardens, App. II, 1901. [Director.] 



Chemist and Druggist. April, 6, 13, 20, 27. [Editor.] 



Diplomatic and Consular Reports, Feb., Mar. [Col. Sec] 



Garden. April, 6, 13, 20, 27. [Purchased.] 



Gardeners' Chronicle, April, 6, 13, 20, 27. [Purchased,] 



International Sugar Journal. April. [Editor.] 



Journal of Botany. April. [Purchased,] 



Joorual Royal Colonial Institute, April. 



More coucerning Truxillo Cocoa jLeaves. (From The Duggist Circular and 

 Chemical Gazette, Mar.) [Dir. R. Gardens, Kew.] 



