(Treatment 1) and an 

 untreated control 

 (Treatment 5) for man- 

 agement of European 

 apple sawfly and plum 

 curculio. In accor- 

 dance with label rec- 

 ommendations, we ap- 

 plied four sprays of 

 Imidan (=label stan- 

 dard) at 10-day inter- 

 vals begimiing at pink 

 (May 5), four sprays of 

 Surround at 10-day in- 

 tervals beginning at 

 pink (May 5), and three 

 sprays of Actara at 10- 

 day intervals begmning 

 at petal fall (May 15). 

 For the duration of the 

 study, the untreated 

 control received no in- 

 secticide or fungicide. 



To monitor the 

 buildup of early-season 

 pest damage, we 

 sampled 20 fruit from 

 the central tree of each 

 treatment plot (240 

 fruit per treatment) for 

 damage inflicted by 

 European apple sawfly 

 and plum curculio. 

 Such samples were 

 taken twice during the 

 growing season, in 

 early June and mid 



June. At harvest, we increased our samples to 50 fruit from 

 the central tree of each treatment (600 fmit per treatment). 



For control of European apple sawfly (EAS), we found 

 no significant differences among treatments (including un- 

 treated controls) in samples drawn during June (Table 2). 

 These data indicate fairly clearly that pressure from EAS 

 was too light throughout the block to allow judgment of treat- 

 ment effectiveness with limited fruit samples (mean dam- 

 age=0.0% to 1 .7%). However, more thorough samples taken 

 at harvest yielded a significant difference between all chemi- 

 cally treated plots (mean damage=0.2%) and untreated con- 

 trols (2.3%). These data suggest that Surround and Actara 

 (at either rate) can offer control of a light EAS population 

 comparable to that of a standard Imidan program. 



No treatments provided a commercially acceptable level 

 of plum curculio (PC) control through June, with damage 

 reaching 7.8% to 12.4% in chemically treated plots by June 



19 (Table 3). However, for this trial, it is important to bear 

 in mind the likelihood that many PCs found safe harbor in 

 untreated controls (which would not be found in commer- 

 cial orchards) during June, likely spilling over into treated 

 areas. This may account for the high level of PC injury seen 

 across all chemical treamients. That said, all treatments 

 yielded significant reduction of PC oviposition injury in 

 comparison with untreated controls (23.0% PC injury) 

 through June 19. Further, all chemical treatments provided 

 statistically identical control of PC, again suggesting that 

 Surround and Actara (at either rate) may offer control of PC 

 comparable to Imidan. In samples taken at harvest (reflect- 

 ing the full effects of June drop and possible late-June buildup 

 of PC injury), all experimental treatments maintained a level 

 of PC control that was statistically equal to treatment with 

 Imidan. However, in late-season samples, it was often diffi- 

 cult to distinguish between distorted PC oviposition scars 



24 



Fruit Notes, Volume 65, 2000 



