WSU Whatcom County Extension

Integrated Pest Management for Blueberries

Harvest

Decision Making Matrices

 

Pest
Brief Description
Damage / Reason for Concern
Monitoring Approaches
Decision Points / Tolerances
Management Options
Follow Up
INSECTS

 

Aphids

Offspring are still being produced, but rate of population increase is lower.

Deformation of leaves.
May cause honeydew formation and sooty mold on fruit.
May transmit viruses; Scorch virus is especially problematic.

Check 5 leaves at each plant.
Look for winged and wingless aphids as well as for aphid mummies.   Make a note if you find honeydew and sooty mold on fruit, indicating a high level of aphids.

Beneficial insects should be starting to keep this pest in check at this time.  If populations are still increasing, consider treatment after harvest.

Reduce excessive nitrogen use.  Aphids (and other piercing/ sucking insects) are attracted to high nitrogen tissues.

Foster habitat for beneficial insects.

Chemical control.

Continue scouting for aphid and beneficial insect populations.

Fruit Contaminants

Egg sacs of spiders or pupae of lacewing or syrphid flies contained in the blossom end of the fruit.

Fruit with these contaminants will appear as a white furry mat in the blossom end, rendering the fruit unsaleable. These are beneficial insects so control is not recommended.

Inspect 5 fruit per plant for contaminants at the blossom end.

Train harvesting and processing crew on recognizing these contaminants.

Contaminated fruit will need to be removed on the grading line.

Remove fruit from the line when showing contamination.

Train grading staff on what to look for in the way of fruit contaminants.

Spotted Wing Drosophila
(SWD)

Adults are small flies (less than 1/8 inch) with red eyes and a pale brown thorax and abdomen with black stripes on the abdomen. Adult males have a black spot towards the tip of each wing. Adult females have a large, saw-like ovipositor for inserting eggs into fruit.

This fly damages ripe and ripening fruit. Females lay 1-3 eggs per fruit by inserting their ovipositor into the fruit causing small scars, indented soft spots, and bruises on the fruit surface.

Eggs hatch and the larvae develop and feed inside the fruit, causing the flesh to collapse around the feeding site within as few as two days.

As soon as fruit begins to ripen place traps in fields using a 16oz plastic cup containing about apple cider vinegar. Monitor traps twice per week and record number of adults found.

Also, monitor for small puncture (oviposition scar) wounds on fruit and soft fruit.

No threshold or tolerance level available.

In most cases detection is the advised threshold.

This is a new pest to the Pacific Northwest; therefore, thresholds and management are not well established.

Continue to monitor traps and check fruit for small scars and the presence of larvae.

DISEASES

 

Mummyberry

Infected fruit will show up in the clusters and drop to the ground to overwinter.  Mummyberries appear pink and puckered with brown and corky inside tissue.

Loss of yield due to infected fruit.

At each plant, check 5 fruit clusters for symptoms.  Examine the ground beneath the plant to see if any infected fruit has fallen to the ground.

No tolerance established.

If on a small farm, clean up dropped fruit following harvest

Chemical

Watch for fallen berries following harvest. 

Godronia Canker

Cankers are growing in size through the season; they will appear to be more like a bull’s eye with a gray center.

Stem girdling when cankers get large.

Inspect 20 plants per site.
Look for leaves turning color earlier than ususal acting as red flags in the field.

No tolerance established

Prune out infected wood.
Choose resistant varieties.

Educate farm workers on identification of cankers and pruning out methods.

Shock Virus

Infected plants may appear normal except for the lack of fruit.

Loss of yield for at least one year.

Keep monitoring plants with symptoms.  Those that have not recovered should be tested by Oregon State University for Scorch Virus.

No tolerance established; plants usually recover.

Plants will probably have recovered by this stage.

Continue monitoring plants with shock symptoms.

Botrytis

Gray fuzzy mold becomes more active on ripening fruit.

Reduces fruit quality and yield.

Inspect 5 fruit clusters per plant.
Look for gray fuzzy mold.

No established tolerance

Harvest frequently where gray mold is commonly seen, especially in conditions of warm and wet weather.

Continue scouting for infected fruit.

Anthracnose

Softening salmon colored spore masses may be seen on infected fruit.

Infected ripe fruit can cause a great reduction in yield.

Inspect 5 fruit clusters per plant for signs of infection.  Rate the infection (low, medium, high)

Consider treatment if levels of infection are medium to high, especially if weather is warm and wet.

To reduce the spread among harvested fruit, reduce the temperature of the fruit to 32°F as soon as possible.

Chemical

Train harvesting and processing crew on how to identify infected fruit.

Alternaria Fruit-Rot

Ripe fruit may show caving in and greenish-gray spores near the flower end.

Reduction in yield and fruit quality.

Inspect 5 fruit clusters per plant.  Look for infection symptoms.  Rate the infection level (low, medium, high).

Consider treatment if levels of infection are medium to high.

Avoid over ripening by harvesting in a timely fashion.  Cool fruit immediately after harvest, and avoid wounding fruit during harvest.

Train harvesting and processing crew on how to identify infected fruit.

Scorch Virus

Plants infected with scorch virus will not be recovering at this time as are those with shock virus.

Plant and field death.
This virus can be spread quickly through a field and between fields.

Scouting for infected plants should be done through the entire field.  Plants suspected for Scorch (or shock) virus should be tested immediately.

Zero tolerance. 

No treatment available for this disease.
Plants must be removed from the field as soon as identified.

Continue monitoring and testing for virus in field.

VERTEBRATE PESTS

 

Birds

Several types of birds may be present and have the potential to cause damage in a field. Starlings, robins, house finches, and red-winged blackbirds are common.

Damage to fruit can be caused in several ways; fruit may be knocked off of bushes during foraging, eaten wholly by the bird, or punctured or pecked at by a bird.

Scout for birds in the early morning or just before dusk. Identify type of birds present, number present, and change in population size.

Consider treatment if problematic birds are present. Cater management plan to type and number of birds present.

Several types of management options are available. A management plan should be developed that is appropriate to farm site and surrounding properties.

Continue to scout for birds in the field and adapt management plan accordingly.

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WSU Whatcom County Extension • 1000 N. Forest St., Bellingham, WA 98225 • (360) 778-5800 • whatcom@wsu.edu