SCIENCE. 



[Vol. XIV. No. 347 



I believe I am warranted in the following conclusions: the 

 arsenites and carbolized plaster will protect against the plum cur- 

 culio if they can be kept on the tree or fruit ; but, in case of very 

 frequent rains, the jarring method will not only be cheaper, but 

 much more effective. Again : as our wild fruits are more cleared 

 away, we must have plums in our orchards to protect the apples 

 from the curculio. When apples are seriously stung, they become 

 so gnarled and deformed as to be worthless. It will pay, then, to 

 set plum-trees near by or among the apple-trees. Then we will 

 escape mischief among our apples from the curculio, and will only 

 need to spray our apples once to destroy the codling-moth, and can 

 treat the plum-trees three or four times with Paris-green or carbo- 

 lated Hme, in case we have only occasional showers, or can jar the 

 trees when the rains are very frequent. For the apples we can use 

 London-purple (one pound to two hundred gallons of vi'ater) ; for 

 the plums we must use Paris-green (one pound to two or three 

 hundred gallons of water). If the carbolated plaster is preferred, 

 we use one pint of crude carbolic acid to fifty pounds of land- 

 plaster. This is thrown freely over the trees, so as to strike every 

 plum on the tree which is being treated. 



Another very important practical point has been suggested by 

 the past season's experience with these insecticides. I refer to the 

 danger of applying them before the blossoms fall. Bees are quite 

 as susceptible to these poisons as are the codling-larvas and curculio. 

 In their good work of collecting nectar and fertilizing the blossoms, 

 they are very certain to take the poison as well, if the trees have 

 been sprayed. Of course, there is no excuse for spraying at so 

 early a date, as neither the curculio nor codling-larva commence 

 their attack till the blossoms fall. Thus for the object in mind, as 

 well as for the safety of the bees, delay should be insisted upon. I 

 think we as scientists, and all educated men, should pronounce 

 vehemently and with one voice against spraying our fruit-trees with 

 the arsenites till the blossoms have all fallen. We should even go 

 further : we should secure the enactment of laws .which would visit 

 any such offence with tine and imprisonment. Such laws would 

 prove a ready and active educator. 



In the past season many bee-keepers have lost severely from the 

 neglect of their fruit-growing neighbors to observe this caution. I 

 will only mention two cases. Mr. John G. Smith, Barry, III., writes, 

 " One of my neighbors, owning an orchard of about one hundred 

 acres of apple-trees, sprayed the trees with Paris-green and water 

 just as they were in full bloom. The result is that ten or twelve 

 bee-keepers are ruined." The imago no less than the larvs and 

 pupae were destroyed. Mr. J. A. Pearce, Grand Rapids, Mich., 

 was also a heavy loser from the same cause. His bees likewise 

 died in all stages of development. 



It is well to remember and to urge that this loss is not confined 

 to the bee-keeper, for the fruit-grower as well as the apiarist needs 

 the bees and their work to insure his best success. It only re- 

 quires, then, that our people know the truth, to insure againt loss 

 n this direction. 



Another practical question of no small moment in this use of the 

 arsenites refers to injury to the foliage of the trees treated. In an 

 elaborate series of experiments the past season, we desired to learn 

 the effect on different trees of the different arsenites, and whether 

 the date of treatment and atmospheric condition had any influence. 

 From these experiments I think we are warranted in the following 

 conclusions : — 



First, London-purple is more injurious to the foliage than is 

 Paris-green, and white arsenic (arsenious acid) is more harmful 

 than is either London-purple or Paris-green. This is doubtless 

 owing to the soluble arsenic, which is quite abundant in London- 

 purple, and almost absent in Paris-green. In one experiment it 

 was seen that the colored water after London-purple fully settles is 

 very destructive to foliage, while aniline is not at all harmful. This 

 agrees with the experiments of Professor C. P. Gillette, made in 

 1888, where white arsenic was found very destructive to foliage. 



Second, Peach foliage is especially susceptible to injury, and 

 cherry foliage the least so of any of the kinds treated. 



Third, It would seem that London-purple and white arsenic, 

 used just before a rain, are more harmful than when used during a 

 drought. We not only saw greater injury when a rain followed 

 spraying within two or three days, but secured the same results by 



spraying, soon after treatment, with pure water. This also accords 

 with the view that the injury comes from the presence of soluble 

 arsenic. 



Fourth, It would seem that spraying soon after the foliage puts 

 out is less harmful than when it is delayed a few days, or, better, a 

 few weeks. For ten years I have sprayed both apple and plum 

 trees in May, and for several years with London-purple, and often 

 used a mixture as strong as one pound to one hundred, or even 

 fifty, gallons of water; yet in most cases no damage was done. 

 This year I sprayed several trees in May, using one pound to one 

 hundred gallons of water, with no damage. In June and July, 

 spraying the same trees with a mixture only one-half as strong did 

 no slight injury. This fact, if fact it be, accounts for the few re- 

 ports of injury in the past, even with a stronger mixture, and the 

 frequent reports of damage within a year or two, even with a dilute 

 mixture. Then the spraying was confined* to May : now it reaches 

 to June, or even to July. 



Fifth, London-purple may be used on apple, plum, cherry, pear, 

 and most ornamental trees, but on these should never be stronger 

 than one pound to two hundred gallons of water. If the applica- 

 tion is to be repeated, as it must be for the curculio, to prove effec- 

 tive, or if it is to be used in June or July, Paris-green should be 

 used in the same proportion as above, or else we should only use 

 one pound of London-purple to three hundred gallons of water. I 

 now think that this necessity is more due to time of application 

 than to the fact of increased quantity of the poison. 



Sixth, If the arsenites are to be used on the peach to defend 

 against the curculio, Paris-green only should be used, and that not 

 stronger than one pound to three hundred gallons of water. With 

 the peach the poison is not only absorbed, coloring the tissue 

 purple or brown, but even the petiole or stem of the leaf is wea- 

 kened, and the leaf falls. Thus in several cases where we used 

 London-purple (one pound to two hundred gallons of water) or 

 white arsenic, the peach- leaves all fell off. White arsenic colors 

 the tissue the same as does the London-purple, showing once more 

 that it is the soluble arsenic, not aniline, that does the mischief. 



Seventh, The injury done to the foliage is never immediately ap- 

 parent. It usually shows somewhat the second day ; but the full 

 injury is frequently not manifest till the fifth day, and often not till 

 the tenth. 



Another important practical question which I have tried to settle 

 this season (1889) concerns the danger of pasturing under trees 

 which have been sprayed with the arsenites. 



A gentleman wishing to spray his orchard, in which he was pas- 

 turing seventy-five hogs, consulted me as to the wisdom of doing 

 so without first removing the swine. I told him I believed there 

 was no danger. I said, " Use a mixture of one pound of London- 

 purple to two hundred gallons of water, watch your hogs closely, 

 and, if any seem affected, remove all at once, and I will be respon- 

 sible for damages to the amount of twenty-five dollars." The 

 gentleman did so, and reports no damage. 



In the following experiments I used the mixture of twice the 

 strength which should be used, that the experiment might be the 

 more convincing. I used one pound to one hundred gallons of 

 water. In every case the spraying was very thoroughly done. 

 Care was taken that every twig and leaf should be drenched. 



In tree No. i a thick paper was placed under one-half of a rather 

 small apple-tree. The space covered was six by twelve feet, or 

 seventy-two square feet. The paper was left till all dripping ceased. 

 As the day was quite windy, the dripping was rather excessive. In 

 this case every particle of the poison that fell from the tree was 

 caught on the paper. Dr. R. C. Kedzie analyzed the poison, and 

 found four-tenths of a grain. Tree No. 2 was a large tree, with 

 very thick foliage. Underneath this tree was a thick carpet of 

 clover, blue-grass, and timothy just in bloom. The space covered 

 by the tree was fully sixteen feet square, or equal to two hundred 

 and fifty-six square feet. As soon as all dripping had ceased, the 

 grass under the tree was all cut very gently and very close to the 

 ground. This was taken to the chemical laboratory and analyzed 

 by Dr. R. C. Kedzie. There were found two and two-tenths grains 

 of arsenic. Now, as our authorities say that one grain is a poison- 

 ous dose for a dog, two for a man, ten for a cow, and twenty for a 

 horse, there would seem to be small danger, from pasturing our 



