314 REPORT OF STATE BOARD OF HORTICULTURE. 



He drenched some apple trees with london purple, used twice as strong- 

 as recommended. All the poison which dripped off was caught on a paper, 

 and the amount of arsenic on this pajier then' determined by the chemist. 

 In one case, it amounted to two-fifths of a grain, and in another to two and 

 one-fifth grains. Although these analyses showed that there was little or no 

 danger, the matter was more fully tested by thoroughly spraying other trees 

 under which was growing some bright and tender grass. All of the grass 

 was cut close to the ground and Professor Cook fed it to his horse; and no 

 injury resulted. The experiment was repeated later with the same result. 

 Next three sheep were kept till hungry and then put in a pen made under 

 another tree which had just been sprayed. All of the grass was eaten with 

 no injurious results. This experiment was twice repeated with the same 

 result. Thus practical experiments confirmed the conclusions of the chemist. 



As no poison is usually sprayed on the fruit after it is half grown, the rain 

 and wind would naturally remove the last particle of it before the fruit was 

 picked. Chemical analyses have shown that there was not the slightest 

 trace of arsenic on the mature apples which had been sprayed several times 

 when they were small. 



Why the sjiray may not he so effective on pears — Several fruitgrowers have 

 asked us to explain why they were unable to control the codling moth on 

 pears as effectively as they do on apples. We can only offer the following 

 suggestions on this point : Our observations on the young pears after the 

 blossoms fall show that the calyx lobes never draw together as they do on 

 most varieties of apples (see Figs. 145 and 146). While it would thus be just 

 as easy to lodge some poison in the blossom end of the pears, the fact that 

 the calyx cavity remains open or unprotected would permit the poison to be 

 easily washed out by rains or blown out by winds. Whether the recently- 

 hatched apple worm has similar habits when born on a pear as it does on an 

 apple, we can not say from observation. Possibly, however, the fact that 

 the calyx cavity is open, may cause the worms to enter the fruit at once, 

 thus taking but few if any meals in the blossom end. Thus the fact that it 

 will doubtless be more difficult to keep a dose of poison on pears, owing to 

 the open calyx, may partially explain why it may be more difficult to control 

 the insect on this fruit. 



In 1874, Riley recorded that experiments in Illinois had shown that pears 

 were mostly injured by the- second brood of the apple worms. Washburn 

 recently reached a similar conclusion from his observations in Oregon. As 

 it has been shown that we can reach but few of the worms of the second 

 brood on apples with a poison spray, it is evident that a similar treatment 

 on pears would have little ett'ect, providing that most of the injury to pears 

 is done by the second brood of worms. Perhaps we have been spraying too 

 early for the insect on pears. Wherever it does serious injury to pears, it 

 would be well to make some careful experiments with the poison sprays. 



Bi'iefly stated, no panacea for the codling moth has yet been found, but 

 by thorough work by a paris-green spray, we can often save at least seventy- 

 five per cent, of the apples that would otherwise be ruined by the worms. 

 Where more than tAvo broods of the insect occur during the season, as in 

 Kansas, Nebraska, Oregon, New Mexico, and neighboring localities in the 

 west, and in the south, the poison spray is not so effective, for although 



