Adults
White, non-UV reflective sticky traps are attractive to apple sawfly adults and can be used to monitor populations in orchards.
- Place the traps in orchards at the late green cluster to pink bud growth stage of Cox.
- Examine the traps at least weekly throughout the blossom period and count the number of sawfly adults caught.
- No economic thresholds have been determined and, in any case, these will depend on many factors including the size, design and density of traps being used.
- However, on susceptible varieties, a catch of even one or two adults per trap per week can indicate that significant losses could occur if the crop set is light.
- If adult sawflies are caught, an assessment of the number of egg insertion scars should be made in the latter part of bloom to determine whether or not a post-blossom insecticide spray for control of sawfly is needed.
Egg insertion scars
Examine 100 trusses (5 from each of 20 trees) for egg insertion scars on the side of the receptacle.
- Treatment is likely to be justified if 11 or more scars are found.
Infestation and damage at and shortly after petal fall
Inspect the young developing fruitlets for signs of infestation or damage, such as ribbon scars.
- If infestation is caught early enough, the worst effects of damage can be avoided by prompt application of an insecticide spray.
Damage during the growing season, at harvest or during grading
If significant damage to fruits is seen one season, treatment the next season to avoid damage intensifying is justified.