34 EXPERIMENT STATION BULLETIN. 



Sprayed. The development of leaf-curl on the sprayed trees was 

 severe, but the condition was much better than that of the dusted trees. 

 The failure to control the disease on the sprayed trees was probably due 

 to two factors : First, the warm weather before the spraying was done, 

 and, second, the material used possibly was not effective. No definite 

 tests have been made with dry lime-sulphur to control leaf-curl but 

 since it has not given satisfactory control of apple scab it is doubtful 

 if it would control leaf -curl. 



MAGNESIUM ARSENATE ON PEACHES 



A block of Early Michigan peaches on the Graham Experiment Sta : 

 tion farm at Grand Rapids was used for testing magnesium arsenate. 

 For comparison, one plot was sprayed with lead arsenate and another 

 left unsprayed. 



Materials. The block of trees was divided into four plots of from 

 fifteen to twenty-five trees each and treated as follows: 



Plot 1. Check. Unsprayed. 



Plot 2. Corona dry lead arsenate. 1 Ib. in 50 gal. and 3 Ibs. hydrat- 



ed lime added to each 50 gal. 



Plot 3. Dow magnesium arsenate. 1 Ib. in 50 gal. No lime added. 

 Plot 4. Dow magnesium arsenate. 1 Ib. in 50 gal. and 3 Ibs. lime 



added to each 50 gal. 



The materials were used as listed above for the first application. For 

 the second application Plots 2, 3 and 4 were all sprayed with self-boiled 

 lime-sulphur and the poisons were used in combination with it. 



Applications. Two applications were made: 



1st. As the last of the "shucks" were falling. 

 2nd. Two weeks after the first. 



The spraying was done under high pressure -and with a spray gun. 



RESULTS 



Check plot. The foliage of the trees in this plot was in excellent con- 

 dition throughout the season. 



Lead arsenate plot. The foliage of all trees in this plot was in very 

 good condition. There was practically no injury; only an occasional 

 small spot could be found. There was no loss of leaves from these trees. 

 The condition was the same after both applications. 



Magnesium arsenate. No lime added. Within two or three days 

 after the first application the foliage began dropping. Practically every 

 leaf showed injury and defoliation was very severe. Many small limbs 

 were entirely defoliated so that the limb died and the fruid dried up. 



Magnesium arsenate. Lime added. The effect upon the trees in this 

 plot was much the same as where no lime was used but the injury was 

 not so severe. 



Magnesium arsenate with self-boiled lime-sulphur. The effect of this 

 combination was about the same as when used with lime. 



The combined effect of two applications on Plot 3 resulted in almost 



