EXPERIMENT STATION BULLETINS. 433 



TABLE 1.— PRE-PINK SPRAYING OF DUCHESS APPLES. 1921 



Treatment 



Check 



Regular schedule. 

 Pre-Pink schedule 



No. of 

 applications 





 3 



4 



No. apples 

 examined 



Scabby, 

 per cent 



The "pre-pink" application resulted in a marked reduction in the amount 

 of scab. Practically all of the 16 per cent of scab on the fruit from the "pre- 

 pink" plot was in a very inconspicuous form and was not easily recognized 

 as such even by careful examination. The scab on the fruit from the plot 

 which did not receive the "pre-pink" apphcation was in much larger and 

 more conspicuous spots and was easily recognized. 



Observations in other experiments. In several other experiments with 

 apples the amount of scab apparently caused by infections previous to the 

 pink or cluster application was determined. This type of scab is referred 

 to on other pages as "early" scab. The amount of "early" scab varied from 

 10 per cent to 30 per cent with the different varieties. On highly susceptible 

 varieties such as Mcintosh, this form of scab developed into quite large spots 

 which were easily noticeable but with a more resistant variety, such as 

 Baldwin, the scab spots were small and were not easily detected. 



General observations. The fruit in other orchards which did not receive 

 the "pre-pink" application was studied whenever possible to determine the 

 amount of scab which had been caused by early infections. Such observa- 

 tions were made at Grand Rapids, Belding, Fennville, Sister's Lake, South 

 Haven and other places and the principal varieties noticed were Duchess, 

 Wealthy, Transparent, Chenango, Mcintosh and Fameuse. In nearly every 

 orchard studied the control of the later infections was very good but in every 

 instance there was a noticeable amount of scab which had developed from 

 early infections. 



CONCLUSIONS AND RECOMMENDATIONS. 



The results of the experiments and observations here reported indicate 

 that a "pre-pink" apphcation is very desirable for the best control of apple 

 scab. Further studies as to scab spore discharge and more extensive field 

 experiments are desirable and will be continued, but the information available 

 now justifies the recommendation of a "pre-pink" application, particularly 

 on susceptible varieties. This application is not to be considered as a "cure- 

 all" for apple scab but simply is one of the applications necessary in the 

 successful prevention of scab. 



All spraying for scab must be considered as "insurance" and as no grower 

 can accurately predict what weather conditions will prevail during any given 

 period, one caimot safely omit the application which would protect the fruit 

 and foliage during that period. The period between the ideal "pre-pink" 

 stage and the pink or cluster stage may be two days or two weeks in length. 

 We do know, however, that rainy weather is apt to prevail and primary 

 infection occur before the pink spray. In large orchards it is impossible to 



