Apple Spraying Experiments in 1916 and 1917. 123 



.74 and .17 per cent of scabby apples respectively. Plot 5 and 

 the west half of Ben Davis No. 1, sprayed according to the mod- 

 ified program, produced 1.59 and 1.24 per cent of scabby apples 

 respectively. The slightly better results obtained with both 

 methods of treatment in No. 1 may be due to the fact that the 

 trees are smaller here with more open spaces, allowing better 

 ventilation and better penetration of sunlight. In each instance 

 a greater per cent of merchantable apples was obtained with 

 the modified spraying program, than from 3 applications of the 

 standard lime-sulphur and arsenate of lead combination . This 

 was directly due to the smaller amount of fruit russeting with 

 the former. 



It has already been shown by comparison of the results 

 obtained on plots 1 and 4 in 1916 that omission of the pink bud 

 spray entirely, did not lead to a material increase of scab. There- 

 fore it is not surprising that the amount of scabby fruit, ob- 

 tained with the modified spraying program on plot 5, or 1.59 per 

 cent, should be practically the same as where double strength 

 arsenate of lead was used alone throughout the season on plot 

 6, which was 1.61 per cent. 



These results and those previously secured which have to 

 do with the same subject, taken together with those obtained in 

 1917, illustrate very well the difficulties which may arise if in 

 apple spraying experiments one attempts to draw definite con- 

 clusions from work covering only a few seasons. It might seem 

 that the necessity for using the stronger lime-sulphur for the 

 pink-bud spray is not indicated by the results secured in 1916 

 or in the 4 or 5 previous seasons. During this period plots 

 sprayed with the standard combinations of lime-sulphur and ar- 

 senate of lead showed but little better scab control than where 

 the pink-bud application was omitted entirely. It is also true 

 that 3 applications of double strength arsenate of lead alone pro- 

 duced during successive seasons very efficient scab control when 

 compared with standard dilution lime-sulphur containing one 

 pound of dry arsenate of lead in 50 gallons. In spite of all of 

 this the writer has not felt ready to advocate that two or even 

 three applications of double strength arsenate of lead alone 

 should be depended upon for the control of apple scab in com- 

 mercial orchards in Maine. In view of the fact that in some 

 seasons in Maine, and in all seasons according to the expressed 



