16 



below average rainfall contributed to tliis phenomenon. Apple 

 rust mites, which cause little damage except at very high popu- 

 lation (about 300/leaf) but may serve as an alternate food source 

 for Amblyseius fallacis , were found in substantially higher numbers 

 in IPM than Check blocks. 



Table 2. Mean abundance at peak sampled population of pest and 

 predaceous spider mites in relation to acaricide sprays, 1980. 



Acaracide 

 dosage 



Number of mites per leaf 



Two- Apple 



equivalents European spotted rust Amblyseius 

 Orchard type Oil Other red mite mite mite fallacis 



IPM 1.0 0.8 



IPM partial 



cooperator? 0.7 1.4 



Check 1.1 1.8 



8.1 



6.2 



8.4 



2.0 



3.2 

 1.9 



66. 5 



50.4 

 22.4 



0.07 



0.02 

 0.03 



„ . T ^ Actual pesticide rate/100 gal 



Dosage equivalent = -t — r '- 1 — r~- o^ — . . ^ — - 



^ ^ Amt . recommended m Southern 



New England Apple Pest Control 

 Guide 



Predator mite numbers were insufficient to achieve biological 

 mite control because they never exceeded 0.5 per leaf in any block. 

 We believe that the lack of snow cover during the 1979-80 winter 

 may have resulted in substantial overwintering mortality to A. 

 fallacis , as was the case in Michigan after a recent winter with 

 similar conditions. 



Insecticide, aphicide and miticide use . 



IPM blocks received 26% fewer insecticide sprays (average 6.5, 

 range 5-9) than the Checks (average 8.8, range 5-12} or same orchard 

 non-IPM (average 8.8, range 5-10]°. These results appear to indicate 

 that growers (same-orchard non-IPM and Check) are implementing some 

 aspects of IPM on their own. Partially cooperating IPM growers 

 applied 11°6 fewer sprays than good cooperators. However, any sav- 

 ings in spray material and application costs were negated by sub- 

 stantially higher fruit injury levels in these blocks. 



IPM growers applied 26% and 531 fewer miticide sprays compared 

 to Check and partially cooperating 1PM growers, respectively (Table 

 3). Use of oil as an ovicide was nearly identical in IPM and 

 Check blocks, but 36% lower in partial cooperator blocks. 



8 



Data incomplete 



