Table 3. Trap captures and larval injury in blocks receiving mass application of sex pheromone 

 to disrupt mating of red banded leafroller and lesser appleworm moths in 1989. 



*Total-season captures of males in 5 monitoring traps per block. 



**Based on 200 fruit sampled per block at harvest. Most sampled fruit were doubles (stems 



closely opposing one another). 



* * *Treated with 400 pheromone dispensers per acre on April 20 and August 1 (for red banded), 



or on May 19 and August 2 (for appleworm). 



codling moths, so that it might be necessaiy to remove 

 a wide variety of plants over long distances from the 

 orchard perimeter to preclude immigration of larvae 

 (blowing in on threads of silk that they spin) or of 

 females. Even then, this approach may not succeed 

 because of the ability of several of these pests to tolerate 

 pesticides used against plum curculio. Thus, unlike the 

 situation with codling moth, early-season leafrollers 

 and lesser appleworms may not be completely elimi- 

 nated from the orchard interior by early season pesti- 

 cides directed against plum curculio. 



The best future hope for managing leafrollers and 

 lesser appleworms under second-stage IPM principles 

 may lie in one of two practices: (1) application of 

 Dipel™ (bacteria that produce compounds toxic to 

 lepidoptera) or Dimilin™ (an insect growth regulator) 

 at the time when first-generation larvae are active 

 (early May to early June) or (2) application of synthetic 

 sex pheromone to disrupt mating and deposition of 

 fertile eggs. In collaboration with Bicontrol LTD of 

 Queensland, Australia, in 1989 we evaluated season- 

 long use of mating disruption pheromone against red 

 banded leafrollers and lesser appleworms in 3 commer- 

 cial orchard blocks not sprayed with insecticide after 

 early June. Compared to nearby first-stage IPM 

 blocks, there was a very strong reduction in captures of 

 male moths in pheromone traps in the pheromone- 

 treated blocks (Table 3). This result illustrates the 

 power of mass application of pheromone to prevent 



mate-seeking males from locating sources of female 

 pheromone released in the traps. Presumably the 

 males are similarly prevented from finding living fe- 

 males in the orchard. However, there was only a 

 moderate reduction of red banded leafroller fruit injury 

 and no reduction of lesser appleworm injury in the 

 pheromone-treated blocks (Table 3). Failure to obtain 

 good control of larvae in the pheromone-treated blocks 

 may have been due to immigration of fertile females or 

 larvae (blowing in on silken threads). More in-depth 

 orchard research is needed before a mating-disruption 

 approach to control these pests becomes feasible. 



Foliar Pests and Their Natural Enemies 



Data in Table 4 show that in all years where 

 sampled, predatory mites, aphid predators, and 

 leafminer parasitoids were more abundant in second- 

 stage than in first-stage IPM blocks. On the other 

 hand, averaged over the 3 years, pest mites, apple 

 aphids, and leafminers were no more abundant in 

 second-stage than in first-stage blocks, despite no pes- 

 ticide treatments against these pests after early June in 

 the second-stage blocks. Similarly, woolly apple aphids 

 and potato leafhoppers were essentially no more evi- 

 dent in second-stage than first-stage blocks across the 

 3 years. In 1987 and 1988, white apple leafhoppers 

 were considerably more abundant in second-stage 

 than first-stage blocks. In 1989, use of endosulfan in 



Fruit Notes, Winter, 1990 



