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INTERNATIONAL CONGRESS OP VITICULTURE 



Table V. Relative toxicity of neutral and alkaline Bordeaux mixtures to the 

 spores of Phytophthora infestans and Plasmopara Viticola.9 



The data presented are for indirect germination, the experiments being 

 carried out according to the method described by Reddick and Wallace.^ 

 The sporangia were placed on the sprayed slides in drops of distilled water 

 and were kept at or near the optimum temperature for germination which 

 usually occurred in the witnesses in about two hours. 



Number of 

 Experiments 



3 

 6 



Mixture Germination Tests with Spores of Plasmopora viticola - 



Mixture 



Number of Non-Toxic 

 Experiments at % Cu. 



1.97 mgrm. 

 1.97 mgrm. 



1.97 mgrm. 

 3.95 mgrm. 



3.95 mgrm. 



1.97 mgrm. 

 1.97 mgrm. 



Ratio 



Amount of Copper Germination Tests With Spores 



*The germination tests quoted in this table were kindly made for me by Dr. I. E. Melhus. 



From the data presented in the above table we may conclude that the 

 efficiency of the unit copper is the same in all three types of Bordeaux 

 mixtures. 



V. 



The adhesiveness of the copper fungicides has been studied by various 

 authors whose results for the different types of Bordeaux mixtures currently 

 met with I have gathered together in the following table. 



9 Reddick, D. and Wallace E. On a laboratory method of determining 

 the fungicidal value of a spray mixture or solution. Science n. s. 31. 1910. 



