482 ANNUAL REPORT OF THE Off. Doc. 



than good. Six samples of the Paris green nsed by as many dififerent 

 farmers were analyzed and the lowest i)er('entage of arseuious oxide 

 combined with copper was fifty-three and seventy-three hundredths 

 (53.73) and the highest fifty-six and twenty-two one-hundredths 

 (56.22), or 3.73 per cent, and 6.22 per cent, higher than required by 

 the State law. This showed that the composition of the poison was 

 all right and that the cause of its failure to kill the bugs must be 

 due to something other than the composition, which was found to 

 be the case. It was found that approximately twenty per cent, of 

 these samples of Paris green did not pass through a screen of one 

 hundred mesh to the inch. In order to make certain that finer 

 grinding was necessary samples of finely ground Paris green were 

 compared with these sam})les and where the finely ground poison 

 v/as used the bugs were killed, while those on the plant sprayed with 

 the analyzed Paris green were not killed. 



This coarsely ground Paris green was mixed with water, even when 

 constantly agitated the larger particles would sink to the bottom of 

 the barrel and carry with them large numbers of smaller particles. 

 But what was still worse, when these coarse particles were sprayed 

 on the potato leaves they formed centers around which collected a 

 large number of smaller particles making the Paris green so dense 

 that it burned the potato leaves and prepared pores for the attack 

 of potato blight. Not only is this coarsely ground Paris green the 

 cause of trouble with potatoes, but it certainly can not be as effective 

 for killing codling moth and other insects. It should, therefore, be 

 insisted that the Paris green be ground to an impalpable powder so 

 that it will easily pass into the cutting or chewing organs of the 

 insect or larva; that it may be evenly distributed over the foliage 

 and fruit of plants, that it will not burn the organs of the trees 

 and plants and in this way itself do some of the injury for which it 

 is applied and prepare the way for the attack of parasitic fungi as it 

 evidently did in the case referred to. 



These observations are not as conclusive as they should be, but 

 from reports of other potato and fruit growers, it appears that we 

 must learn better to prepare these spraying mixtures, or something 

 else must be gotton instead of the sprays now used, that will not 

 injure foliage, fruit or ti-ees; but rather be a benefit such as the 

 self-boiled lime and sulphur spray is. 



SOME FUNDAMENTAL PRINCIPLES IN FERTILITY MAIN- 

 TENANCE 



By R. C. E. WALLACE, Ohio Experiment Station, Wooster, Ohio 



"The soil is the farmer's business capital. He has invested his 

 money in the land aud to it he must look for his returns." What 

 these returns will be depends largely upon the farmer himself. 



If he is to adopt a profitable and permanent system of agriculture, 

 he must put into practice the underlying principles which have been 

 found to be absolutely essential and fundamental to the greatest 



