WSU Whatcom County Extension

Integrated Pest Management for Raspberries

Post-Harvest

Decision Making Matrices

(July through mid-August)

PEST
BRIEF DESCRIPTION
DAMAGE/REASON FOR CONCERN
MONITORING APPROACHES
DECISION POINTS/ TOLERANCE
MANAGEMENT OPTIONS
FOLLOW UP
INSECTS

 

 

Nematodes

 

Microscopic wormlike organisms which damage roots, resulting in stunted unproductive plants. The two most common species are Pratylenchus penetrans (root lesion) and Xiphinema bakeri (dagger nematode).

 

Feed on and damage roots. One species of dagger nematodes, (X. americanaum) transmits Tomato Ring Spot Virus.

 

Soil and root samples from good v. poor areas in a field should be sent to a laboratory and analyzed for population size and makeup.

 

Time of sampling will influence nematode densities, thus thresholds.
Depends on plant age, variety, soil type, other plant pests and diseases, nematode complexes, management inputs, & etc.

 

Multiple options in pre/re plant situation.  Only one currently registered nematicide (with expected loss of registration) for soil borne nematodes in existing planted fields.

 

Resample fields the following year in the fall.

 

Raspberry Crown Borer

 

Adult, egg, and caterpillar stages may be present during this time. Adult clear-winged moths look like a black and yellow wasp. Caterpillars range in length from 1/4" 1" depending on age.

 

Caterpillars tunnel in canes and crown area, weakening plants. 
Larval feeding reduces cane vigor and yield.

 

Check lower canes and crowns for presence of caterpillars.
Record % infested hills.

 

If more than 5% of the plants have damage caused by borer larvae feeding, chemical controls are recommended.

 

Insecticide application to lower canes and crown area. October is preferred timing. If damage is present, treat for two consecutive years to obtain control.
With effective treatment, fields can be restored.

 

Check canes next season.

 

Spider Mites
(Two-spotted mite is the most common spider mite)

 

Adults are about 1/50" long, have eight legs, and are light tan or greenish in color with a dark spot on each side, which looks like a saddle.

 

Feed on underside of foliage.
Reduced plant vigor, water loss and
premature defoliation. Excessive defoliation after harvest can reduce yield the following season.

 

Continue to monitor spider mites and predator mites closely in mid- to late- August. Spider mites can increase in numbers rapidly during mid - late August.
Collect 10 leaflets at each site and record the number of spider mites and predator mites.

 

Apply miticide if populations reach 25 mites per leaflet before September.

 

Miticide application if threshold is reached. Keep plants adequately irrigated.

 

Fields that have been sprayed should be sampled 5-7 days after the application.

 

Strawberry Crown Moth (SCM is more common in the Willamette Valley and Southwest Washington)

 

SCM should be in larvae form during this time. Mature larvae are about 20 mm long, white, with a dark brown head.

 

Larvae can cause economic damage by girdling the canes causing the plants to become stunted and have poor vigor.

 

Watch for weakened areas in the field and signs of feeding on the outside of the crown.

 

No threshold is established. Consider chemical control if adults were found in the trap during the harvest period.

 

The same fall insecticidal drench used to control Raspberry Crown Borer will also control SCM.

 

Monitor adult flight the following season to evaluate control measures.

DISEASES

 

 

Cane Blight

 

Primocane wounds during harvest are sites for infection. Brown to black lesions develop on new infected canes.

 

Infection of new canes allows fungus to carryover to following season.

 

Examine primocanes for evidence of damage from catcher plates. Scrape off bark on primocanes near catcher plate wounds in late fall/October. Diseased canes will have a reddish, spreading, vascular lesion.
Record % infected hills.

 

Review catcher plate damage to primocanes and history of infection.
If 1-3% of canes are infected, consider treatment the following season during or immediately after harvest.

 

Fungicide application directed at base of primocanes.

 

Monitor closely in late fall and following spring.

 

Phytophthora Root Rot

 

Soilborne fungus which can cause root and crown rot. Infection favored by saturated soil conditions. Diseased plants have lack of feeder roots, poor vigor canes. Interior of major roots and crown are brown to black.

 

Fruiting canes are dead. Primocanes may wilt or die.

 

Target yellow plants with sudden wilting.
Pull samples as soon as symptoms are seen.  Send for ELISA/ PCR test.

 

There is no threshold, decision making around this pest complex is complicated.
Growers should consider these factors: age of planting, size of effected area, results of pathogen testing, variety.

 

Sample suspect areas to confirm infection. Cultivate so that water drains away from plants into the center of the alleyway. Also subsoil down each alleyway to improve the movement of water into the soil. This can also be used to fracture compacted soil beneath equipment wheel tracks. Apply fungicides within row in October through early November where disease is confirmed as cause of decline.

 

Monitor diseased areas closely next season.

 

Spur Blight

 

Brown wedge shaped lesions on primocane leaves. Petiole left attached to primocanes. Dark brown area on cane around bud may be present.

 

Can damage/weaken buds. Increases susceptibility to winter injury.
When diseased canes become fruiting floricanes the next season, side branches from diseased buds are often weak,

 

Continue to examine foliage for wedge-shaped lesions and lower primocane area for cane lesions. 
Record % infected hills.

 

Use disease prevention strategy. Consider field history - past incidence of infection.
Consider treatment in following year if 10% of hills are infected.

 

Spraying at this crop stage is too late for good control.

 

Rate disease incidence on primocanes now or following spring.

 

Yellow Rust

 

Black teliospores replace the orange-yellow spores on the underside of leaves.

 

Teliospore stage allows the fungus to overwinter.

 

Inspect leaves for presence of teliospores and degree of infection.

 

Presence of teliospores. Identify fields with moderate to heavy degree of infection.

 

Delay tying canes in infected fields until leaves have dropped, if practical. Cultivate leaves that have dropped into the soil to reduce carryover inoculum.

 

Monitor closely next spring.

 

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WSU Whatcom County Extension 1000 N. Forest St., Suite 201, Bellingham, WA 98225 (360) 778-5800 whatcom@wsu.edu