THE EXPERIMENT STATION. 145 



Promotion of Agricultural Science" at the Toronto meeting, and printed 

 and distributed as Bulletin 53 of this Station. So important are the con- 

 clusions deduced from these experiments that I will briefly state them here : 



First-*-Early spraying seems less harmful to foliage than does later. 

 Spraying in May rarely does harm, while the same in June or July, even 

 with a more dilute application, is often a serious damage. 



Second — There seems to be no essential difference as to the time of day. 

 Spraying early in the morning, at noontide, or towards night-fall, each 

 seemed about as the others, as to injury produced on the foliage. 



Third — A rain soon after spraying increases the damage to the foliage, 

 especially if we use London purple or white arsenic. 



Fourth — London purple is more injurious to tender or susceptible foliage 

 than is Paris green, while white arsenic is more injurious than is London 

 purple. 



Fifth — White arsenic should never be used in such warfare. London 

 purple may be used on all trees, except the peach, early in the season, in 

 May, but never stronger than one pound to two hundred gallons of water. 

 If used on shade trees or on plum trees in June and July the proportions 

 should be one pound to three hundred gallons of water. For peach trees, 

 Paris green only should be used, and this not stronger than one pound to 

 two hundred, and possibly three hundred gallons of water. And for all 

 trees late in the season, June and July, it is much safer to use Paris green 

 than to use London purple. Probably it is the soluble arsenic that does 

 the mischief, and this is likely to be present in considerable quantities in 

 London purple, while it is nearly absent in Paris green. 



Sixth — There seems no danger in turning stock into an orchard imme- 

 diately after it has been sprayed with the arsenites. If properly sprayed — 

 that is, sprayed with a dilute mixture as suggested above — the amount of 

 poison which falls to the grass below, and which would be eaten, even if all 

 the herbage was cropped by the stock, would be far too slight to do any 

 harm. Chemical analysis, as well as direct experiment with horses, sheep 

 and hogs, determines this question beyond any chance of error. 



FIGHTING THE CUECULIO. 



This year, as last, we sprayed our plum trees with London purple, and 

 dusted them with carbolized plaster. We used one pound of London purple 

 to two hundred gallons of water, and mixed one pint of strong, crude car- 

 bolic acid with fifty pounds of common land plaster. As last year, so this, 

 we repeated each application twice, making three times in all. The results 

 this year were very different from those of last year. Trees treated, like 

 those untreated, lost every plum. This year we had hard rains almost every 

 day. These doubtless so washed off the poison or plaster that they were no 

 preventive of the work of the beetles. My experiments last year, together 

 with those of Prof. C. M. Weed, of the Ohio station, in 1888 and 1889, and 

 those of Prof. S. A. Forbes, of Illinois, show quite conclusively that the 

 arsenites will prevent in great part the work of the curculio if we can keep 

 the poison on the leaves and fruit. The same is true of carbolized plaster. 

 But my experiments this season prove that in very rainy seasons the old 

 jarring method is not only cheaper, but the only effective method yet known. 



19 



