THE EFFECT OF SURFACE FILMS OF BORDEAUX 



MIXTURE ON THE FOLIAR TRANSPIRING 



POWER IN TOMATO PLANTS 



JOHN W. SHIVE AND WILLIAM H. MARTIN 



New Jersey Agricultural Experiment Station, New Brunswick, New Jersey 



The use of Bordeaux mixture as a fungicide has given rise to 

 many problems of physiological interest and importance. Fre- 

 quent reports of increased and prolonged vitahty in plants, and 

 greater crop yields resulting from the use of this spray mixture, 

 in the absence of all disease producing organisms, have aroused 

 widespread interest and have led to many investigations in an 

 effort to determine the nature of the influence of this fungicide 

 upon healthy plants. During the past twenty years an exten- 

 sive literature has accumulated dealing with questions of the 

 influence of Bordeaux mixture upon various plant physiological 

 processes, as well as upon plant structures. The results de- 

 rived from the experimental work on the influence of this spray 

 mixture on the rates of water loss by transpiration from sound 

 plants, have led to conflicting opinions among investigators. 



Studies of the influence of Bordeaux mixture on the rates of 

 transpiration have been stimulated by the belief that prolonged 

 vitality and greater yield from crop plants, such as the potato, 

 following the use of this spray, are the result of a decrease in 

 the rates of water loss, due to the presence of the spray material 

 on the leaves. An explanation of this apparent conservation of 

 the moisture in the leaves of the potato plant in dry seasons 

 has been offered by Clinton, ^ upon the theoretical ground that 

 the stomata and water pores of the leaves are clogged wdth 

 the sediment of the spray, thus checking the loss of moisture by 

 transpiration. The shading influence of Bordeaux mixture has 



1 Clinton, G. P., Spraying potatoes in dry seasons. Conn. Agr. Exp. Sta. 

 Report, 1909-10: 729-752. 



67 



THE PLANT WORLD, VOL. 20, NO. 3 

 MARCH, 1917 



