14- 



Conclusions 



Sticky-coated, 20 x 30 centimeter red traps, hung at 

 height inside the canopy o£ apple trees, were effective fo 

 itoring P. crataegella adults. We recommend that the trap 

 at a rate of 1 per 0.8-1.2 hectares*, and that a pesticide 

 (oxamyl or fenvalerate) against the adults be applied befo 

 white shows on the flower petals if cumulative pre-bloom c 

 (from silver-tip through late pink) reach or exceed 6 adul 

 trap. This tentative action threshold is conservative, al 

 for both the reproductive potential of P. crataegella and 

 stress due to drought, calcium chloride burn, and/or mite 

 Additional work is planned for the 1983 season to further 

 this threshold and to develop an additional action thresho 

 unstressed trees. This trap should be valuable in reducin 

 need to wait until first generation mines appear before a 

 spray decision can be accurately made. 



chest 

 r mon- 

 s be used 



treatment 

 re any 

 aptures 

 ts per 

 lowing 

 for tree 

 injury, 

 validate 

 Id for 

 g the 

 leafminer 



0.6r 



0.5 - 



0.4 - 



AVG 



MINES 



PER 



LEAFo.3 



0.2 



0.1 



O ^ 



15 



45 60 75 



NO. LM PER TRAP 



H. 



00 211 



Figure 1. Regression of first generation mines per leaf on 



visual trap captures in 21 commercial orchard blocks 



One hectare = 2.471 acres 



