- 18 - 



in 1976, spider mites were, on the average, slightly more abundant 

 in the alternate middle than every middle plots. 



Some apple scab was observed in each block, but did not appear 

 to occur in any greater amount in the alternate middle plots. 



A cost-benefit analysis of the every vs. alternate middle 

 treatments in Orchard C was conducted by students in a graduate 

 insect pest management class at UMASS (see Fruit Notes 43(2) :3-7). 

 The results are summarized here: 



Dollar Costs/Acre 



Every Alternate 

 Middle Middle Difference 



Spray materials* 135.70 67.85 -67.85 



Labor (at $3/hr) 10.50 5.25 - 5.25 



Fuel, oil, filters, 

 etc. 5.00 2.50 - 2.50 



Value of fruit loss 



owing to insect 5 



disease injury** 32.72 44.72 +12.00 



Cost reduction from 



alternate middle 



program*** -63.60 



(Since a reduction in net costs is the same as an increase 

 in returns, the value of $63.60 should be regarded as an 

 increase in net returns.) 



* Includes cost of all insecticide, miticide, and fungicide 

 materials. 



** Fruit yield was sampled on randomly selected trees and found 

 to be equal in the alternate and every middle plots. Total 

 yield estimated at 750 bushels/acre in each plot. Only 0.181 

 and 0.06% diseased fruits appeared in the 3360 fruits sampled 

 at harvest in the alternate and every middle plots, respectively 

 Fifty percent of the fruits injured by plant bugs plus all 

 fruits injured by other insects were considered as culls. Total 



bushels of culls per acre were 8.18 and 11.18 for the every and 

 alternate middle plots, respectively. Culls were given an 

 average value of $2/bushel (combination of #2 fruit and cider j 

 apples). All undamaged fruit was given a value of $6/bushel. ' 



The analysis does not include possible additional costs (if 

 any) of grading out the greater number of insect- and disease- 

 injured fruits (11.18 - 8.18 = 3.0 bushels/acre) from the 

 alternate middle plots. 



*** 



