WSU Whatcom County Extension

Integrated Pest Management for Blackberries

Post-Harvest

Biology and Monitoring

 

Insects
Diseases
Vertebrates

     • Raspberry Crown Borer
     • Strawberry Crown Moth
 

     • Blackberry Rust *

     • Voles

*More commonly found on ‘Evergreen’ cultivar.

 

Biology

Insects

Raspberry Crown Borer

Adult moths emerge in August and are active until late September. The day flying adult is a clear-winged moth that resembles a yellow jacket wasp in color and size. Females lay up to 140 reddish brown eggs on the underside edges of leaflets in August or September. Small caterpillars hatch from these eggs, crawl down to the base of the canes, and form an overwintering cell in the side of the cane. Second year caterpillars, which tunnel into the canes and fleshy roots, may be present at this time of the year as well.

 

Strawberry Crown Moth

The strawberry crown moth is in larvae form during this period and is feeding on the outer crown and root surface. As larvae mature, they bore deeper into crowns and are found in the center of the crown after about one month of feeding. Larvae feed in the crowns until early October and then spin a cocoon to overwinter. There is one generation each year.

 

Diseases

Blackberry Rust

Black pustules (teliaspores) will begin developing among the uredinia (yellowish-orange pustules) in late summer and early fall on infected leaves. These black pustules are responsible for continuing the disease cycle the following spring. Field renovation practices that destroy previously diseased plant parts will contribute to the effectiveness of chemical control program the following spring.

 

Vertebrates

Voles

Voles resemble house mice; they are 6-9 inches long, and gray or brown in color. They create tunnels in the soil and feed on plant roots and foliage near the ground. Their gnawing and chewing can girdle roots, crowns, canes and may lead to cane loss. Their tunneling creates air pockets in the root zone, which may further impact plant development.

 

Monitoring

Follow general guidelines in the “Introduction” section. For each pest below, record pest numbers or symptoms on record sheet.

Insects

Raspberry Crown Borer

  • Check lower canes and crown material closely in weak areas of a field for first or second year caterpillars, particularly if adult crown borers are seen during the late summer months. Record the percentage of infested hills.
  • Remove collapsed or dying canes and inspect around the crown for sings of larvae feeding.
  • October is the preferred month for treating infested fields.

 

Strawberry Crown Moth

  • Watch for weakened areas containing brittle or collapsed canes. Examine the crown and lower canes for signs of boring. Record the percentage of infested hills.
  • Fall is a good time for treating infested fields, which usually will correspond with chemical drench used to control the raspberry crown borer.

 

Diseases

Blackberry Rust

  • Conduct a visual search at each site for symptoms associated with blackberry rust and record level of damage on a scale of 0 to 3.
  • Scout field for overwintering black pustules residing on leaves attached to canes or trapped in cane bundles in order to evaluate the effectiveness of chemical program.

 

Vertebrates

Voles

  • Fall monitoring is done to determine populations before winter when crop damage can occur.
  • Look for tunnel entrance holes about one inch in diameter, surface runways through grass, droppings and/or chewing marks on canes and roots.
  • Monitoring stations can be constructed using a protected shelter to cover a runway or tunnel entrance. Shelters can be constructed using a roofing shingles or PVC piping. Place an apple wedge as bait underneath the shelter. Check the apple bait every 24 hours for 2-3 days. Inspect the apple wedge for feeding damage. Four to eight bait stations per acre can provide an accurate assessment of vole populations.
  • Treatment Threshold - management is needed when 40% of the bait stations show positive feeding damage after 24 hours. Monitor again 2-3 weeks following treatment to determine efficacy.

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WSU Whatcom County Extension • 1000 N. Forest St., Suite 201, Bellingham, WA 98225 • 360-676-6736 • whatcom@wsu.edu