Type of season 

 (Mills period) 



6 Rubigan/Dithane), if ap- 

 plication costs exceed $13.00, 

 it would be less expensive to 

 apply Rubigan/Dithane than 

 a standard treatment. If 

 Rubigan is used at the 4 oz 

 rate, then application costs 

 need to exceed only $6.00 for 

 economy. (Note, however, 

 that our results with this rate 

 may not be commercially ac- 

 ceptable.) 



When 6 standard sprays 

 are needed versus 4 Ru- 

 bigan/Dithane sprays, the 

 break-even points for appli- 

 cation costs are the same: 

 $13.00 at the 6 oz Rubigan 

 rate and $6.00 at the 4 oz rate. 

 If the season is such that the 

 numbers of standard and 

 Rubigan/Dithane applica- 

 tions are similar, the break- 

 even points increase. So, at 7 

 standard vs. 6 Rubigan/ 

 Dithane applications, appli- 

 cation costs need to exceed 

 $30.00 (unlikely) for econ- 

 omy. 



In fact, it is more likely 

 that the Rubigan/Dithane 

 applications will save 2 or 3 

 sprays, and that the number 



of applications will be 9 vs. 6, or 6 vs. 4, or some combina- 

 tion in between. The IPM block at the Horticultural 

 Research Center has received an average of 8.5 dosage 

 equivalents of fungicide in each of the past 8 years, with a 

 range of from 6 to 11 applications. (Last year was the only 

 year in which 6 dosage equivalents were used, largely 

 because Rubigan was used for the first time in the block.) 

 Similarly, Dr. Robin Spitko of New England Fruit Consult- 

 ants reports an average of 8.3 dosage equivalents in or- 

 chards that they scout, with a range of 6 to 11. In view of 

 that, it may be important to calculate application costs, in 



Table 4. Break-even point for non-fungicide application costs under different 

 types of seasons and varying numbers of applications. 



Number of Number of 

 standard Rubigan/Dithane 

 applications applications 



Break-even point' 



6 oz 



4 oz 



Heavy 10 



Moderate - Heavy 9 



Average 6 



Light 4 



Light 4 



7 

 6 



4 

 3 



4 



$16.00 

 $13.00 

 $13.00 

 $22.00 

 none 



$8.00 

 $6.00 

 $6.00 

 $10.00 

 none 



Hf application costs are above the figure, the 10-day program is less expen- 

 sive; if application costs are below the figure, the standard program is less 

 expensive. 



order to determine whether a 10-day program would be 

 cost-effective under a given farm's conditions. 



Of course, the convenience of a 10-day program also 

 should be considered. And, there may be additional cost 

 efficiency when a 10-day schedule allows an insecticide to 

 be applied with a fungicide, but a standard program would 

 not. A 10 day schedule offers considerable flexibility, and 

 does not appear to cost a great deal, if any, more than a 

 conventional program, even without considering possible 

 convenience and additional savings. 



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