16. 



Mite populations followed similar trends, with the exception 

 that, in 1980, mite numbers (given in mites/lea£) were 65% lower 

 in the alternate vs. every middle treatment blocks. 



Three year cost-benefit analysis 



While we are not able to perform cost benefit analyses on the 

 1976 and 1977 data owing to differences in sampling techniques and 

 data collection methods, we believe that the composite of the 1978, 

 1979, and 1980 data indicates the potential benefits of alternate 

 middle spraying over time. 



Table 4 indicates that for the latter 3 years, growers rea- 

 lized a net benefit from alternate middle spraying of $41.40 to 

 $85.38 per acre. Although it is difficult to make comparisons 

 between years owing to variability in costs from year to year, 

 alternate-middle spraying would appear to result in an average net 

 benefit of about $67.00 per acre. 



Table 4. Cost benefit comparison of alternate vs. every middle 

 spray treatments, 1978-1980^. 



Cost reduction/acre due to alternate-middle 



spraying 



1978 1979 1980 



Insecticide ^ Miti- 



cide spray materials -$29.61 -$48.05 -$53.22 



Spray application 



costs - 8.87 - 14.22 - 12.41 



Value of fruit loss 



due to insect injury - 2.92 - 23.11 - 10.72 



Net benefit from 



alt. middle spraying +$41.40 +$85.38 +76.35 



z 



Labor costs: 1978 - $3.50/hr; 1979 - $5.00/hr.; 1980 - $5.50/hr. 



Fuel costs: 1978 - $1.50/A; 1979 - $2.00/A; 1980 - $2.20/A 



Fruit value: Variable in each year based on current market quo- 

 tations at harvest. 



Pesticide costs: Based on Coop. Extension Service suggested retail 

 prices . _ 



The value of $67.00 average net benefit per acre compares to 

 an average net benefit over the same period of about $105.00 per 

 acre (exclusive of scouting costs) from the IPM scouting and grower 



