DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 35 



complete defoliation. On many trees, after the effects of the magnesium 

 arsenate had passed, the only foliage left was the new growth that had 

 developed after the spraying. 



In Plot 4 the total injury was not so great and resulted in less per- 

 manent injury to the tires. 



A COMPARISON OF IHLl'TH A \ 1 > ( '< >.\< MOXTIIATKD IH'ST MlXTl'RKS 



WITH SKi.F-noiu:i> Li.MH-st i.riiru 



A block of Crosby peaches on the (Irahani Experiment Station Farm 

 at <lrand Rapids was used Tor this experiment. 



Material*. The block of trees was divided into four plots and treated 

 as follows : 



Plot 1. Check; untreated. 



riot '2. Self-boiled lime-sulphur. Lead ai senate added when neces- 

 sary. Lead arsenate with lime was used for the first appli- 

 cation. 



Plot 3. Dilute dust. 5040-10 mixture for two applications and 

 r(l-.")0 mixture for the last. 



Plot 4. Concentrated dust. 90-10 mixture for two applications and 

 straight sulphur for the last. 



Applications. Three applications were made. 



1st. Just as the last of the "shucks" fell. 

 2nd. Two weeks after first. 

 3rd. July 30. 



The dusting was done with a large power duster and the spraying 

 with a spray gun. 



RESULTS 



Disease and Insect Control. There was no injury by insects or dis- 

 eases on the check plots so no conclusions can be drawn regarding 

 their control. 



Foliage Injury. There was no foliage injury found at any time in any 

 plot. 



Jiijnry to Fruit. There was an occasional peach which was injured 

 by the dusting materials. This was very rare and occurred only when 

 the outlet had been close to the tree and a heavy coating of dusting 

 material was deposited on the fruit. The injury occurred then only 

 when the fruit was exposed directly to the sun. An injured peach is 

 shown in Fig. 14. This type of injury is of little consequence as it 

 does not occur under normal conditions. 



