Jan. 1923] annual report 13 



velopment in the sprayed plants. A milk of lime wash of the same strength 

 in lime as a 1:1 Bordeaux mixture had practically the same effect upon the 

 sprayed plant as the latter. The fertility of the soil in which the plants were 

 growing did not affect the response obtained, but spraying with a 1:1 mix- 

 ture had a beneficial effect when the i)lants sprayed were grown in soil 

 much too dry for normal development. 



It has been stated that plants sprayed with Bordeaux mixture transpire 

 more actively at night than non-sprayed plants; and it was found that when 



1:1 Bordeaux mixture increaseil transpiration at night, a l:alk mixture 

 and a milk of lime wash caused a similar response. The increased transpira- 

 tion that occurs at night is not the cause of the differences in behavior ob- 

 served between sprayed and non-sprayed plants; for Bordeaux mixture 

 1:1 and milk of lime have a similarly depressing effect upon vegetation, 

 while Bordeaux mixture l:alk is neutral in action. The effect of Bordeaux 

 mixtures and milk of lime on plants at night, therefore, is less important 

 than the effect produced by these washes during the day time. In fact, it 

 was observed that sprayetl plants do not necessarily trans[)ire more active- 

 ly during the night time. Evidently Bordeaux mixtures and milk of lime 

 possessed uniler conditions of darkness properties in common and under 

 conditions of sunlight dissimilar properties. And, in fact, it was found that 

 Bordeaux mixture 1:1 and milk of lime were less transparent to the solar 

 spectrum than Bordeaux mixture l:alk, but that the Bordeaux mixtures 

 and milk of lime were opaque to radiations of long wave length, Bordeaux 

 mixture 1:1 and milk of lime being more opaque than Bordeaux mixture 

 1 :alk. Therefore, under conditions favorable for radiation at night, sprayed 

 plants should transpire more than non-sprayed plants and it was found 

 that they actually did so. 



The Adhesive Qu.\lity of Copper Acetates. 



Further investigation into the basic action of spray materials was made 

 by O. Butler (Botany) and T. O. Smith (Agricultural Chemistry) in con- 

 nection with the study of the adhesiveness of copper acetates. It is known 

 that the decomposition of the copper acetates upon the sprayed plants causes 

 their adhesiveness, and the present work has been to determine both the 

 effect of duration of drying, and the effect of an addition of gelatine. One 

 per cent, mixtures of both neutral and basic acetate of copper were sprayed 

 on glass slides; and the interval between the application of the wash and 

 the incidence of rain was from 24 hours to 15 days. When the mixture 

 did not contain .05 per cent, gelatine, the data obtained showed that the 

 decomposition of the neutral acetate measured in terms of adhesiveness is 

 roughly proportional to time; in the case of the basic acetate of copper the 

 rate of decomposition is extremely rapid during the first four days but con- 

 tinues from thence on more slowly. The adhesiveness of the neutral acetate 

 of copper never became equal to that of the basic acetate of copper. When 

 gelatine was added to the washes, the adhesiveness of the neutral acetate 

 of copper became at the end of forty-eight hours virtually the same as that 

 of the basic acetate plus gelatine and was only slightly lower at each of the 



