84 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



Extent of the experiments: As has already been indi- 

 cated Ben Davis trees only have been used each year. In many 

 respects this variety is very satisfactory for the purpose. It is 

 quite susceptible to spray injury and would hardly be classed as 

 particularly resistant to scab. The number of experimental 

 trees the first season was 128 but during the last 5 years it has 

 varied from a little less than 150 to nearly 300. The policy now 

 followed is to use 24 trees to a plot or 4 rows of 6 trees each. 



Methods used: To obtain records of results for comparison 

 it is now the custom to reject the crop obtained on the two out- 

 side rows, or at least the outside half of these rows. This is to 

 avoid the effects from the spray drifting across from adjoining 

 plots which received different treatments. At harvest time the 

 entire crop from the portion of the plot so selected, or 20 bar- 

 rels of it selected at random if the crop amounts to more than 

 this, is carefully sorted and examined. The total number ot 

 fruits, the number of scabby and russeted and the percentages 

 of the Tatter, as well as the percentage of perfect apples are 

 determined and recorded. During the summer observations are 

 made at frequent intervals and a careful record made of the 

 effects of the different sprays on the foliage. 



As far as possible all plots receiving the same number of 

 applications are sprayed on the same day. Very little trouble 

 has been experienced with scale or blister mite so dormant 

 sprays have been used only in exceptional cases and for special 

 plots as will be described later. In other words, the present 

 discussion is almost wholly limited to the action of sprays ap- 

 plied to trees in leaf for the control of apple scab. Dormant 

 sprays are only considered in connection with their possible ef- 

 fects in controlling the scab fungus and in the production of 

 spray injury. 



Unless certain applications were omitted for a definite purpose 

 on individual plots, 3 applications have been made — the first 

 when the fruit buds were showing pink, the second just after 

 the petals fell and the third between two and 3 weeks later. 

 On account of seasonal conditions the date of the first applica- 

 tion has varied considerably. The earliest was May 8, 1913, 

 and the latest were May 23, 1914, and May 24, 1912. The sec- 

 ond date has been more constant, the limits being from May 30 

 to June 7, and in 4 out of 6 seasons from June 3 to 6. The 



