446 THE MONTHLY BULLETIN". 



trees. Nevertheless, after taking this into account, the results tended to 

 show the advantages of the lime-sulphur sprays, commercial or home- 

 made, over Bordeaux in a season which put all spray materials to a 



severe test. 



The experiment for 1911 was planned not only to secure further data 

 along the lines indicated in the previous year 's work, but also included 

 several new aspects of the spraying problem. Some recent data in 

 spray experiments tended to show that lead arsenate, in addition to its 

 great insecticidal poAver, possessed some fungicidal value also. This 

 was one of the new points of inquiry embraced in the second season's 

 work. Another was the determination of the limits of dilution of lime- 

 sulphur concentrates. 



It is a well known fact that in using the lime-sulphur preparations 

 instead of Bordeaux mixture in orchard spraying we are substituting 

 for a spray that at the time of application is insoluble, one that is soluble 

 and more or less caustic, according to the strength of the solution. The 

 basis, therefore, for the proper use of the lime-sulphur sprays has been 

 the determination of the strength of the stock solution, and its dilation 

 for use according to its density. Simple instruments for this purpose 

 and dilution tables graded for a scale of densities have been, and still 

 are the only safe means of using lime-sulphur as a summer spray 

 which, so far as known, will insure both fungicidal effectiveness and 

 freedom from spray injury. 



Nevertheless it is a matter of practical importance and interest to 

 determine what may be the limits of dilution for a specific density, in 

 regard to injury and efficiency; in other words, can a solution of a 

 known density be safely used at a reasonably greater strength than 

 that indicated by its place in the dilution table, or can it be diluted 

 beyond the amount indicated in the table and still be an effective 

 fungicide ? 



The trees used in this work of 1911 were the same as those of the 

 preceding year. The plots being fewer in number, each comprised more 

 ti-ees. Two plots were sprayed with lead arsenate at two different 

 strength.s. Three others were treated with boiled lime-sulphur at three 

 different strengths — one at the standard dilution, one 25 per cent 

 stronger and one 25 per cent weaker. One plot was again reserved for 

 treatment with Bordeaux mixture. All four were used in combination 

 with lead arsenate. 



It is impossible in the time at my disposal to go into all the details 

 of the second season. Two factors were responsible for the prevention 

 of any justifiable conclusions regarding insect or fungous control. These 

 were a phenomenal season of drought and heat, which prevented the 

 developm.ent of fungi, and an equally notable absence of injurious 

 insects. This was proved by the many unsprayed orchards in the 

 vicinity which produced fine fruit, without fungus blemisli or insect 

 injury. What relations, if any, the hot, dry summer had to the absence 

 of insects is not clearly known; the extreme dryness ea.sily accounts 



