ORCHARD SPRAYING EXPERIMENTS ' II. 2/ 



of solution is not indicated in any way. Again, if the same 

 percent of injury can be secured from both the lime-sulphur- 

 lead arsenate combination (plot E), and the insoluble arsenate 

 used alone (plot E) ; and if a double dose of arsenate (i. e., 

 4 lbs. to 50 gals.) used alone produces injury half as great as 

 th'e 2 to 50 formula, it is difficult to point out any results that 

 may well be attributed to chemical action. 



Furthermore, the gas sprayer cannot well be held accountable 

 for the results on the lime-sulphur plots at Highmoor, since 

 these are contradicted by the results in the Keyser orchard at 

 Greene, where the nature of the application was identical. 



The following facts must also be kept in mind. The russet- 

 ing in 191 1 was in large measure no more severe than the 

 "natural" russeting found on unsprayed trees. The weather 

 conditions, according to past experiences, were adverse to the 

 production of russeting; nevertheless, in a season almost ideal 

 for the development of fine fruit, the bordeaux mixture was 

 still able to effect a very high percent of injury (Table 8;. 

 The cause of the latter is well known to be indirectly due to 

 meteorological factors acting upon the insoluble spray. Why 

 may not such factors, if they are able to effect bordeaux injury 

 in a comparatively favorable season, produce some damage to 

 fruit otherwise treated? It would at least seem probable that 

 if the sprays themselves (not including bordeaux) were pri- 

 marily responsible, that some indication would have shown 

 itself in the form of leaf injury on the plot treated with lime- 

 sulphur solution 20 percent in excess of the recommended 

 strength. 



In general, then, we are led to the same conclusions published 

 in last year's bulletin on this point,* — namely that spray injury 

 may be, and very likely is, due as much to a physical factor., 

 i. e., the application of a mist or spray to growing plant tissues 

 under extreme, or some now undetermined, but unfavorable, 

 meteorological conditions, as to any chemical action of the 

 material ,used. Certain it is that spraying should be avoided if 

 possible d.uring such extreme heat as was experienced in Maine 

 in July 19.11. 



Fruit growers must not be discouraged by the above state- 

 ment into abandoning spraying operations. Granting the great- 



Me. Agr. Exp. Sta. Bill. 1S9, p. 6g. 



