Conclusions 



Our findings are encouraging for those who wish 

 to employ trunk trap captures as a method of determin- 

 ing whether or not to spray against leafminers prior to 

 the appearance of miners in leaves two or three weeks 

 after petal fall. The data show that a grower has an 

 81% probability of making a correct decision using a 

 threshold of three adults per trap at tight cluster and an 

 83% probability of making a correct decision using a 

 threshold of nine adults per trap at pink. Nearly all 

 failures occur in cases where captures are below thresh- 

 old and do not correctly predict that mines will reach 

 threshold numbers. This is not a major problem, how- 

 ever, because it would still be possible to treat later 

 against first- or second-generation larvae that exceed 

 threshold levels. 



Sticky red rectangles stapled to tree trunks may 



become increasingly valuable as a leafminer monitor- 

 ing tool now that Provado is labeled for use against 

 leafminers. For maximum benefit against first-genera- 

 tion leafminers, it is essential that Provado be applied 

 at petal fall (no earlier due to toxicity to bees and no 

 later due to decreasing effectiveness). Waiting to apply 

 Provado against second-generation leafminers will al- 

 most surely require two back-to-back treatments to en- 

 sure effective control, thereby doubling the cost. If one 

 does not wish to sample leafminer eggs to determine 

 need for a petal-fall Provado treatment, using red rect- 

 angle trunk traps is a good next best bet. 



Acknowledgments 



This work was supported by the Northeast Regional 

 IPM Competitive Grants Program and State/Federal 

 IPM funds. 



10 



Fruit Notes, Spring, 1995 



