26 - 



Results of Modified Models 



After results of the original model were obtained, the magnitudes of the 

 constraints, or resources available, were (^hanged for labor, cooling capacity, 

 and storage. The following is a description of the overall changes made to the 

 constraints and of the responses to those changes. For a more detailed 

 discussion of the modified models, readers should refer to the Extension 

 publication we have written (to be published in January, 1987) that describes 

 this research at greater length. 



Increasing the amount of harvest labor, cooling capacity, or both 

 simultaneously caused greater changes in the planting mix than changes in 

 storage capacity. Therefore, storage capacity was increased to handle all apples 

 and then held kept constant. Harvest labor md cooling capacity were increased 

 only in the most ;onstraining 3-day harvest periods in any year, as opposed to 

 being increased in all harvest periods for any year. This enabled the 

 identification of the harvest periods that demanded the greatest amount of labor 

 and cooling (Capacity. Also, this treatment made it easier to note how the 

 selection of different combinations was influenced by changes in harvest labor 

 and cooling capacity. Cooling capacity was most constraining in year 20, when 

 plantings ivere nature and produced Jtiaxi nurn yields. In this year for harvest 

 periods 4 through 8, cooling was increased in steps from the initial 9,000 

 bushels per 3 days to 10,000, and finally to 11,000 bushels per 3-day harvest 

 period. 



Harvest labor was altered in year 11 for the 2T' through the 4^^ periods 

 (September 7 to 17). The number of pickers was increased in steps from 7 to 8 

 to 9 in year 11. With each picker working 27 hours in a 3-day harvest period, 

 the total hours available for each harvest period increased from 189, to 216, 

 and to 243. In year 20 harvest labor was most constraining during the 4*^" and 

 5^'^ harvest periods (September 14 to 17 and 1'^ to 21), so labor hours available 

 were raised to 5G7 per 3 days (21 pickers) for both periods. 



Marsha I l/M. 26 . Marshall on M.26 was selected for planting most frequently 

 in all models. Overall, this strain-rootstock combination makes the best use of 

 resources as explained previously. However, the advantages do not inply that 

 Marshall/M.26 should be the sole strain planted on the rejuvenated acreage. 

 Such action would result in high labor ind <.ooling requirements concentrated 

 during the days of Marshall/M. 26's peak picking period. Again, the objective 

 vvas to determine the most profitable nix of strain-rootstock combinations that 

 would use the inputs available efficiently. 



If ample harvest labor vas available at matirity of the orchard, 

 Marshall/M.26 replaced acreages selected originally for planting with 

 Marshall/OAR I. In the original model, no Marsiia ll/M.26 was chosen in planting 

 year 3. However, 2.5 acres were chosen when harvest labor and total cooling 

 capacity increased. For planting year 9, the original model decided to plant all 

 5 acres with Marshall/M.26. However, as harvest labor ind cooling became lass 

 constraining, less of this combiiation was chosen, with no Marshall/M.26 being 

 selected for year 10. Probably, this situation arose because labor and cooling 

 capacity were not increased to high enough levels. 



