DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 23 



Insect Control. Both kinds of lead arsenate controlled all insects 

 very satisfactorily. Calcium arsenate did not give quite so good control 

 as lead arsenate. Maynesium arsenate failed to give satisfactory insect 

 control. 



The tabulated results of counts made are given in Table VI IF. 



SI .M.MAKV OF RESULTS OF EXPERIMENTS WITH APPLES 



DUSTING 



*<-<ih Control. In 1918 at Morrice the amount of scab that developed 

 on the untreated trees was not very great, but with Stark there was 

 enough to give a satisfactory check on different materials used. 

 The dusting method gave almost complete control of scab, as there 

 was only 1.1)% of scabby apples in the dusted plot of Stark. With Bald- 

 win there was only 1.1% of scabby apples on the check tree, so the re- 

 sults with this variety are not conclusive. 



At Muir in 1JHS with Northern Spy there was so little development 

 of seal) on the check tree that no comparison can be m'ade of dusting 

 with spraying. 



At Belding in 1918 with Baldwin there was enough development of scab 

 on the check to allow satisfactory comparisons. The dusting method 

 gave nearly complete control of scab and better control than spraying 

 with lime-sulphur solution. Failure of the sprayer to always work satis- 

 factorily probably accounts for part of the scab on the sprayed plot. 



In 11)19 at Grand Rapids dusting gave better control of scab on 

 Duchess than spraying with lime-sulphur solution. The difference, 

 however, was very small. 



/y/.\rr/ Control. In part of the experiments there was so little insect 

 injury on the check trees that no safe comparisons can be made. This 

 is true of the work in 1918 with Baldwin at Morrice and Beldiug and 

 with Northern Spy at Muir. With Stark at Morrice there was consider- 

 able injury by codling moth on the check tree, but dusting gave nearly 

 complete control. In 1919 at Grand Rapids dusting controlled all chew- 

 ing insects very satisfactorily. 



f-'ol i<i</c Injury. The foliage on dusted trees has been in better phy- 

 sical condition in every experiment than where the trees were sprayed. 

 In some cases there has been some development of scab on the foliage of 

 dnsied tiees, but this has never been severe. 



DRY LIME-SULPHURS AND B. T. S. 



Xruft Control. The work with Sherwin-Williams dry lime-sulphur at 

 Grand Ledge gave no conclusive results, as there was so little scab on 

 the check tree. At Grand Rapids in 1919 the work with Duchess gave 

 definite results. Sherwin-Williams and Dow dry lime-sulphurs and 

 B. T. S. all failed to give- satisfactory control of scab. The strength at 

 which these materials were used made little difference in the results. 



