What’s Your Apple IPM Report Card?

Do you know how effective your pest management program was this year? With only a small time commitment required, a harvest assessment can provide information on what part of your management program went well (or not so well).

Advantages to doing a harvest assessment

  • Knowledge of this year’s problems will help you better prepare your IPM program next year.
  • Provides an accurate read of not only the type of damage but also the extent of damage in a block or orchard.
  • Preparedness for early season pest management needs such as sprayer calibration, urea and/or leaf shredding for scab control, dormant oil for San Jose scale or early season copper and other fungicides for fire blight, scab and powdery mildew.
  • Understanding what practices worked and what didn’t will save money in input costs for future management programs.
  • Improves fruit quality for any late season pest issues that may be observed and can be managed prior to harvest. This is particularly helpful if your scout has finished.
  • Highlights any susceptible varieties or hot spots in a block or orchard, which allows targeted monitoring and potential spot treatments in future years.
  • Provides a historical record for reference and increased awareness of potential challenges.

How should you do it? 

In the field:

  • Choose at least 10 (large trees) to 20 (dwarf trees) healthy trees randomly throughout the block.
  • Select 200-400 apples (20-40 apples per tree), turning each to see all sides of the fruit without removing it.
  • Randomly choose fruit from different positions on the trees: upper, inner and outer part of the canopy.
  • Keep records for reference. Looking for a template? Use these scouting sheets for fruit and terminal damage assessments.

If a field assessment is just not feasible prior to harvest, a post-harvest evaluation of fruit can be done. However, this type of assessment will only provide information on severity of damage and not the location in the block this damage occurred. Examine 400-500 randomly selected fruit for each variety from harvest containers. If damage is found, you may want to increase the sample size to thoroughly assess the damage.

What should you look for?

Anything causing 2–5%damage is of concern. For higher value cultivars, consider 1-2% damage for pests causing direct injury to the fruit. Look for presence of:

  • Larvae or larval feeding from oriental fruit moth, codling moth or other caterpillars
    • Oriental fruit moth: tunnel from calyx or stem end; tunnel in flesh of fruit
    • Codling moth: piles of frass at hole which can be side or bottom of fruit; tunnel to seed cavity of fruit
    • European apple sawfly: ribbon-like scar spiralling from calyx
    • Obliquebanded leafroller (or other spring-feeding caterpillars): surface feeding; scarred and misshapened fruit; leaves often webbed to fruit
  • Black caps of San Jose scale and/or halos on fruit surface
  • Distorted fruit caused by spring feeding caterpillar or rosy apple aphid
  • Pits or stings caused by tarnished plant bug, stink bug or apple maggot
  • Raised bumps by mullein bug, plum curculio or other plant bug
  • Blotches/lesions caused by scab, sooty blotch/fly speck, rust or calyx end rot
  • Lace-like russetting caused by powdery mildew
  • Fruit rot
    • Black rot: firm lesion; black fruiting bodies
    • Bitter rot: sunken lesion; orange to salmon-coloured spores
  • Vertebrate feeding such as deer, turkey or other birds

As you walk through the orchard, also make note of damage to leaves, branches and graft unions caused by pests such as fire blight, scab, powdery mildew, leafroller, tentiform leafminer, leafcurling midge, mites and borer.  

Go to Ontario AppleIPM for more information on these pests including descriptions and pictures of typical damage.

Which block should you do?

To get the best idea of what’s happening in your orchard, assess all blocks. If time is limited, give yourself half an hour to one hour per block and select representative areas of the orchard. If you assess the same block every year, you can compare your results and notice trends over time.  

Remember, simply determining this year’s IPM report card will put you ahead of the game for next year’s management program.

Kristy Grigg-McGuffin

OMAFRA Horticulture IPM Specialist