June, 1919] 



ANNUAL REPORTS. 



19 



tinued. Twenty-three copper fungicides and combinations of copper fungicide 

 and insecticides are being studied. 



2. Structure of the Fruit Spur of the Apple. — Work on the histology 

 of the fruit spurs of the apple has been delayed owing to Mr. Doran's resigna- 

 tion on November 1, last. We have, however, found that the opinion current 

 in the literature that the lambourde type of fruit spur is more perishable than 

 the dard type is morphologically sound, as is also the opinion that a dard devel- 

 oping on a lambourde increases the longevity and vigor of the fruit branch. 



3. Chemical Studies of the Apple (in co-operation with the Department 

 of Chemistry). — The work on the distribution of the food materials in the 

 apple tree was concluded during the year; and a summary of the results ob- 

 tained will be found in the report of the Department of Chemistry. 



4. A Study of the Toxic Action of Fungicides. — During the year 

 experiments were made on the toxicitj' of cuprammonium sulphate, normal 

 cupric acetate, and basic cupric acetate to the uredospores of Puccinia antir- 

 rhini and the aecidiospores of Cronartium rihicola. The relative toxicity of the 

 cuprammonium washes to the spores of Plasmopra rihicola was also tested and 

 found to be as follows : 



Relative Toxicity of the Cuprammonium Washes and Cupric Sulphate 

 TO the Spores of Plasmopara Viticola. 



B— HATCH PROJECTS. 



1. The Control of the White Pine Blister Rust on Rises.— Work on 

 this project has been confined to a determination of the minima, optima and 

 maxima temperatures of aecidiospore and uredospore germination and to 

 several experiments on the time elapsing between aecidiospore germination 

 and uredospore appearance. 



2. Snapdragon Rust and Its Control.- — Field experiments on the control 

 of the snapdragon by means of drj' sulphur showed very clearly that this 

 fungicide was inactive under the temperature conditions prevaihng. 



3. Effect of Temperature on the Keeping Quality of Potatoes. — 

 In continuation of previous experiments it was found that potatoes can be 

 stored in reduced oxygen with little loss of weight as compared to those in nor- 

 mal air provided the water transpired is removed without too complete dehy- 

 dration of the atmosphere. An experiment run from January 26 to May 25 

 gave the following results: 



