DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 33 



EXPERIMENTS WITH PEACHES 



The experimental work with peaches was all clone in 1919. There 

 were three separate experiments. One at Saugatuck for the control of 

 leaf-curl by dusting, one at Grand Rapids comparing dilute and con- 

 centrated dusts with self boiled lime-sulphur and lead arsenate' and the 

 third at Grand Rapids as a test of magnesium arsenate in comparison 

 with lead arsenate. 



/ 



DUSTING TO CONTROL PEACH LEAP CURL 



A test was made to determine if leaf curl can be controlled by the 

 dusting method. This work was done in the orchard belonging to Mr. 

 Jas. Boyce which is located about one mile from Lake Michigan and 

 five miles north of Saugatuck. The variety was New Prolific. The 

 trees. w r ere four years old. 



Materials. About fifty trees were used for the experiment. They 

 were divided into two plots and treated as follows: 



Plot 1. Niagara Soluble Sulphur (for dusting). 

 Plot 2. 90-10 mixture of sulphur and lead arsenate. 



Several trees were left untreated as checks. The lead arsenate in 

 the 90-10 mixture was probably of no value except as a sticker. It 

 would not have been used had any other mixture been available at that 

 time. 



Spraying. The main part of the orchard was sprayed by Mr. Boyce 

 with Sherwin-Williams dry lime-sulphur. This material had been held 

 over from 1918 and was used at double the strength recommended by 

 the manufacturers because it apparently had deteriorated in quality. 



Application. The dusting was done on March 7. The material was 

 applied very liberally and from two directions. The spraying was done 

 late in March. There were several daj r s of quite warm weather soon 

 after the dusting work was done and the buds undoubtedly swelled 

 enough to allow an infection of leaf curl. 



RESULTS. 



The leaf -curl injury was very severe in this orchard as weather condi- 

 tions were ideal for its development. The condition of the trees early in 

 June in the several plots was as follows : 



ClH'rk trees. TMie untreated trees were practically defoliated except 

 for some new terminal growth. 



Dusted. 90-10 inli-iurc. Trees dusted with this mixture were in only 

 slightly better condition than the check trees. 



Dusted. Niagara Soluble Kuli>1iur. The trees in this plot were in a 

 slightly better condition than those dusted with the 90-10 mixture. The 

 difference, however, was only very small. 



