What Size of Apple is the Most Prone to 

 Plum Curculio Attack Early in the Season? 



Jaime Pifiero, Everardo Bigurra, Sara Hoffmann, and Ronald Prokopy 

 Department of Entomology, University of Massachusetts 



In the 2000 Issue of Fruit Notes, we reported on 

 the distribution of fruit injury by plum curculios (PC) 

 within the canopies of large, medium, and small trees 

 that were not baited with attractive odor. Our findings 

 indicated that, for large trees, early-season damage to 

 fruit by PC was greatest at tree tops, which was the 

 area in the canopy that also had the largest truit. For 

 medium and small trees, however, damage to fruit by 

 PC was distributed similarly among different sectors 

 of tree canopies, a result that coincided with the 

 distribution of fruit size. 



Here, we aimed at assessing the relationship 

 between fruit size and early-season damage to fruit by 

 PC in large, medium, and small unbailed trees located 



in unsprayed blocks of commercial orchards in 



Massachusetts. 



Materials & Methods 



This study was performed at Atkins Farm and 

 University of Massachusetts Cold Spring Orchard 

 Research & Education Center (Belchertown, MA) in 

 2000. In all, 760 fruit were sampled haphazardly (about 

 30 fruit per tree on each sampling date) from six large 

 (Cortland/M.7), four medium (Priscilla/M.26), and six 

 small (Mclntosh/M.9) trees. Sampling began 2 weeks 

 after petal fall, which occurred by May 18 in 2000. 

 Sampling was performed on June 2 for large trees. May 



E INJURED 

 D UNINJURED 



Small Small Medium Medium 



(May 24) (May 31) (May 23) (May 30) 



TREE SIZE (AND SAMPLING DATE) 



Large 

 (June 2) 



Figure 1. Association between fruit size (expressed as diameter in mm) and early-season injury by 

 PC. Fruit were sampled from small, medium, and large unsprayed apple trees in MassachuseUs in 

 2000. For each doublet of bars, means not superscribed by the same letter are significantly different at 

 odds of 19:1. 



16 



Fruit Notes, Volume 69, Winter, 2004 



