ADDENDA 571 



stock solution. For use in treating the ' sooty mould ' follow- 

 ing the white fly (Alcyrodes citri), dilute this stock solution in 

 the proportion of one part to seven parts of water. 



Webber, Proc. Ninth Ann. Meeting Florida State Hort. 

 Soc. (1896). 



Influence of Bordeaux mixture on the yield of potatoes. 



It has frequently been stated that apart from its fungicidal 

 action, Bordeaux mixture acts beneficially on potatoes, and 

 the result is a better crop. Kirchner has conducted a series 

 of experiments extending over three years, for the purpose of 

 determining the value of such statements. The first season 

 showed practically no difference between sprayed and un- 

 sprayed plots. During the second season the balance was in 

 favour of the sprayed plots, whereas during the third season, 

 when the plants were sprayed four times with a 2 per cent, 

 solution of Bordeaux mixture, the crop yield and starch per- 

 centage were both decidedly in favour of the unsprayed plot. 

 Taking the percentage of the unsprayed plot at 100, then the 

 crop percentage of the sprayed plot would be represented by 

 6o - 4, and the starch percentage as 68*4. 



During the third year of the experiments the weather was 

 very damp and cloudy, and it is considered that possibly the 

 presence of Bordeaux mixture on the leaves might to some 

 extent interfere with the performance of their functions. 



Kirchner, O., Pflanzenkrankh., 18, p. 65. 



Bitter-pit of the apple. This disease has quite recently 

 been investigated by Pole Evans. His summary is as 

 follows : 



' Bitter-pit is an abnormal spotting of the fruit of the apple. 

 It results from the bursting and consequent breaking down 

 of certain cells of the flesh due to too great internal pressure. 

 This great pressure is set up by the external conditions to 

 which the trees are exposed. These trees are not of them- 

 selves plastic enough to adapt themselves to their environ- 

 ment, and thereby regulate their physiological functions, with 

 the result that abnormal forces are brought into play with 

 which the plant is unable to cope in the ordinary course of 

 events. In consequence thereof abnormal physiology leads 

 to disease conditions. The main factors that are responsible 

 for the spotting are believed to be excessive transpiration 

 during the day, followed by its sudden checking and com- 



