o 



'^ I- 



d ^ 



14 

 12 

 10 

 8 

 6 

 4 

 2 



Total no. PCs caught 

 Avg. % injury to fruit 



12 

 10 



>- 

 8 a: 



-- 6 - 



4 ^ 

 < 



-F- 



-- 2 



9-May 12-May 16-May 19-May 23-May 26-May 30-May 2-Jun 6-Jun 9-Jun 13-Jun 16-Jun 27-Jun 



AVG. DATE OF SAMPLING PERIOD 



Figure 2. Relationship between combined captures of PCs on pyramid, cylinder, and Circle traps baited with 

 benzaldehyde, ethyl isovalerate and limonene (in combination with grandisoic acid) and average percent fruit 

 injury for each of the 13 sampling sates from May 9-June 27 in commercial orchards. 



Table 1. Degree of correlation between time or amount of captures of 

 PCs by pyramid, cylinder, or Circle traps baited with benzaldehyde, 

 ethyl isovalerate, or limonene (each in combination with grandisoic 

 acid) and PC injury to fruit in plots where traps were located in 

 commercial orchards 



Correlation r value* 



despite strong numerical trends. Traps baited with any of acid captured no more total PCs than con espondingunbaited 



the remaining three synthetic fruit volatiles (decanal, hexyl traps (Fig. 1). 



acetateandtrans-2-hexenal) in combination with grandisoic For a trap to have real value in monitoring PC abun- 



dance in a commercial orchard, trap 

 captures ought to correlate well in 

 time and total amount with time and 

 total amount ofPCmjury to fruit. Fig. 

 2 shows that when capture data were 

 summed across baited pyramid, cyl- 

 inder and Circle traps and across ben- 

 zaldehyde, ethyl isovalerate and li- 

 monene (in conjunction with 

 grandisoic acid) as bait, periods of 

 increase in trap capture were not well 

 correlated with periods of increase in 

 fruit injury. For example, average 

 fruit injury increased successively 

 from 0.78% to 10.50% of all fruit 

 sampled during each sampling period 

 from May 30 to June 27, but there 

 was no corresponding successive in- 

 crease in captures of PCs during this 

 period by tiaps baited with these tliree 

 compounds. Nor was there any sig- 

 nificant conelation between phenol- 

 ogy of PC trap captures (pattern of 

 occurrence over time) and phenology 

 of PC injury to fruit for any of the 

 individual trap types baited with any 

 of the individual synthetic fruit 

 volatiles in combination with phero- 

 mone (Table 1). There was, however, 

 a strong correlation between total 



*The value of r indicates the strength of correlation. Perfect correlation: 

 r= 1.00 (or -1.00). Total absence of correlation 



34 



Fruit Notes, Volume 65, 2000 



